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ucnv.h (85343B)

---

// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
**********************************************************************
*   Copyright (C) 1999-2014, International Business Machines
*   Corporation and others.  All Rights Reserved.
**********************************************************************
*  ucnv.h:
*  External APIs for the ICU's codeset conversion library
*  Bertrand A. Damiba
*
* Modification History:
*
*   Date        Name        Description
*   04/04/99    helena      Fixed internal header inclusion.
*   05/11/00    helena      Added setFallback and usesFallback APIs.
*   06/29/2000  helena      Major rewrite of the callback APIs.
*   12/07/2000  srl         Update of documentation
*/

/**
* \file
* \brief C API: Character conversion
*
* <h2>Character Conversion C API</h2>
*
* <p>This API is used to convert codepage or character encoded data to and
* from UTF-16. You can open a converter with {@link ucnv_open() }. With that
* converter, you can get its properties, set options, convert your data and
* close the converter.</p>
*
* <p>Since many software programs recognize different converter names for
* different types of converters, there are other functions in this API to
* iterate over the converter aliases. The functions {@link ucnv_getAvailableName() },
* {@link ucnv_getAlias() } and {@link ucnv_getStandardName() } are some of the
* more frequently used alias functions to get this information.</p>
*
* <p>When a converter encounters an illegal, irregular, invalid or unmappable character
* its default behavior is to use a substitution character to replace the
* bad byte sequence. This behavior can be changed by using {@link ucnv_setFromUCallBack() }
* or {@link ucnv_setToUCallBack() } on the converter. The header ucnv_err.h defines
* many other callback actions that can be used instead of a character substitution.</p>
*
* <p>More information about this API can be found in our
* <a href="https://unicode-org.github.io/icu/userguide/conversion/">User Guide</a>.</p>
*/

#ifndef UCNV_H
#define UCNV_H

#include "unicode/ucnv_err.h"
#include "unicode/uenum.h"

#if U_SHOW_CPLUSPLUS_API
#include "unicode/localpointer.h"
#endif   // U_SHOW_CPLUSPLUS_API

#if !defined(USET_DEFINED) && !defined(U_IN_DOXYGEN)

#define USET_DEFINED

/**
* USet is the C API type corresponding to C++ class UnicodeSet.
* It is forward-declared here to avoid including unicode/uset.h file if related
* conversion APIs are not used.
*
* @see ucnv_getUnicodeSet
* @stable ICU 2.4
*/
typedef struct USet USet;

#endif

#if !UCONFIG_NO_CONVERSION

U_CDECL_BEGIN

/** Maximum length of a converter name including the terminating NULL @stable ICU 2.0 */
#define UCNV_MAX_CONVERTER_NAME_LENGTH 60
/** Maximum length of a converter name including path and terminating NULL @stable ICU 2.0 */
#define UCNV_MAX_FULL_FILE_NAME_LENGTH (600+UCNV_MAX_CONVERTER_NAME_LENGTH)

/** Shift in for EBDCDIC_STATEFUL and iso2022 states @stable ICU 2.0 */
#define  UCNV_SI 0x0F
/** Shift out for EBDCDIC_STATEFUL and iso2022 states @stable ICU 2.0 */
#define  UCNV_SO 0x0E

/**
* Enum for specifying basic types of converters
* @see ucnv_getType
* @stable ICU 2.0
*/
typedef enum {
   /** @stable ICU 2.0 */
   UCNV_UNSUPPORTED_CONVERTER = -1,
   /** @stable ICU 2.0 */
   UCNV_SBCS = 0,
   /** @stable ICU 2.0 */
   UCNV_DBCS = 1,
   /** @stable ICU 2.0 */
   UCNV_MBCS = 2,
   /** @stable ICU 2.0 */
   UCNV_LATIN_1 = 3,
   /** @stable ICU 2.0 */
   UCNV_UTF8 = 4,
   /** @stable ICU 2.0 */
   UCNV_UTF16_BigEndian = 5,
   /** @stable ICU 2.0 */
   UCNV_UTF16_LittleEndian = 6,
   /** @stable ICU 2.0 */
   UCNV_UTF32_BigEndian = 7,
   /** @stable ICU 2.0 */
   UCNV_UTF32_LittleEndian = 8,
   /** @stable ICU 2.0 */
   UCNV_EBCDIC_STATEFUL = 9,
   /** @stable ICU 2.0 */
   UCNV_ISO_2022 = 10,

   /** @stable ICU 2.0 */
   UCNV_LMBCS_1 = 11,
   /** @stable ICU 2.0 */
   UCNV_LMBCS_2,
   /** @stable ICU 2.0 */
   UCNV_LMBCS_3,
   /** @stable ICU 2.0 */
   UCNV_LMBCS_4,
   /** @stable ICU 2.0 */
   UCNV_LMBCS_5,
   /** @stable ICU 2.0 */
   UCNV_LMBCS_6,
   /** @stable ICU 2.0 */
   UCNV_LMBCS_8,
   /** @stable ICU 2.0 */
   UCNV_LMBCS_11,
   /** @stable ICU 2.0 */
   UCNV_LMBCS_16,
   /** @stable ICU 2.0 */
   UCNV_LMBCS_17,
   /** @stable ICU 2.0 */
   UCNV_LMBCS_18,
   /** @stable ICU 2.0 */
   UCNV_LMBCS_19,
   /** @stable ICU 2.0 */
   UCNV_LMBCS_LAST = UCNV_LMBCS_19,
   /** @stable ICU 2.0 */
   UCNV_HZ,
   /** @stable ICU 2.0 */
   UCNV_SCSU,
   /** @stable ICU 2.0 */
   UCNV_ISCII,
   /** @stable ICU 2.0 */
   UCNV_US_ASCII,
   /** @stable ICU 2.0 */
   UCNV_UTF7,
   /** @stable ICU 2.2 */
   UCNV_BOCU1,
   /** @stable ICU 2.2 */
   UCNV_UTF16,
   /** @stable ICU 2.2 */
   UCNV_UTF32,
   /** @stable ICU 2.2 */
   UCNV_CESU8,
   /** @stable ICU 2.4 */
   UCNV_IMAP_MAILBOX,
   /** @stable ICU 4.8 */
   UCNV_COMPOUND_TEXT,

   /* Number of converter types for which we have conversion routines. */
   UCNV_NUMBER_OF_SUPPORTED_CONVERTER_TYPES
} UConverterType;

/**
* Enum for specifying which platform a converter ID refers to.
* The use of platform/CCSID is not recommended. See ucnv_openCCSID().
*
* @see ucnv_getPlatform
* @see ucnv_openCCSID
* @see ucnv_getCCSID
* @stable ICU 2.0
*/
typedef enum {
   UCNV_UNKNOWN = -1,
   UCNV_IBM = 0
} UConverterPlatform;

/**
* Function pointer for error callback in the codepage to unicode direction.
* Called when an error has occurred in conversion to unicode, or on open/close of the callback (see reason).
* @param context Pointer to the callback's private data
* @param args Information about the conversion in progress
* @param codeUnits Points to 'length' bytes of the concerned codepage sequence
* @param length Size (in bytes) of the concerned codepage sequence
* @param reason Defines the reason the callback was invoked
* @param pErrorCode    ICU error code in/out parameter.
*                      For converter callback functions, set to a conversion error
*                      before the call, and the callback may reset it to U_ZERO_ERROR.
* @see ucnv_setToUCallBack
* @see UConverterToUnicodeArgs
* @stable ICU 2.0
*/
typedef void (U_EXPORT2 *UConverterToUCallback) (
                 const void* context,
                 UConverterToUnicodeArgs *args,
                 const char *codeUnits,
                 int32_t length,
                 UConverterCallbackReason reason,
                 UErrorCode *pErrorCode);

/**
* Function pointer for error callback in the unicode to codepage direction.
* Called when an error has occurred in conversion from unicode, or on open/close of the callback (see reason).
* @param context Pointer to the callback's private data
* @param args Information about the conversion in progress
* @param codeUnits Points to 'length' UChars of the concerned Unicode sequence
* @param length Size (in bytes) of the concerned codepage sequence
* @param codePoint Single UChar32 (UTF-32) containing the concerend Unicode codepoint.
* @param reason Defines the reason the callback was invoked
* @param pErrorCode    ICU error code in/out parameter.
*                      For converter callback functions, set to a conversion error
*                      before the call, and the callback may reset it to U_ZERO_ERROR.
* @see ucnv_setFromUCallBack
* @stable ICU 2.0
*/
typedef void (U_EXPORT2 *UConverterFromUCallback) (
                   const void* context,
                   UConverterFromUnicodeArgs *args,
                   const UChar* codeUnits,
                   int32_t length,
                   UChar32 codePoint,
                   UConverterCallbackReason reason,
                   UErrorCode *pErrorCode);

U_CDECL_END

/**
* Character that separates converter names from options and options from each other.
* @see ucnv_open
* @stable ICU 2.0
*/
#define UCNV_OPTION_SEP_CHAR ','

/**
* String version of UCNV_OPTION_SEP_CHAR.
* @see ucnv_open
* @stable ICU 2.0
*/
#define UCNV_OPTION_SEP_STRING ","

/**
* Character that separates a converter option from its value.
* @see ucnv_open
* @stable ICU 2.0
*/
#define UCNV_VALUE_SEP_CHAR '='

/**
* String version of UCNV_VALUE_SEP_CHAR.
* @see ucnv_open
* @stable ICU 2.0
*/
#define UCNV_VALUE_SEP_STRING "="

/**
* Converter option for specifying a locale.
* For example, ucnv_open("SCSU,locale=ja", &errorCode);
* See convrtrs.txt.
*
* @see ucnv_open
* @stable ICU 2.0
*/
#define UCNV_LOCALE_OPTION_STRING ",locale="

/**
* Converter option for specifying a version selector (0..9) for some converters.
* For example,
* \code
*   ucnv_open("UTF-7,version=1", &errorCode);
* \endcode
* See convrtrs.txt.
*
* @see ucnv_open
* @stable ICU 2.4
*/
#define UCNV_VERSION_OPTION_STRING ",version="

/**
* Converter option for EBCDIC SBCS or mixed-SBCS/DBCS (stateful) codepages.
* Swaps Unicode mappings for EBCDIC LF and NL codes, as used on
* S/390 (z/OS) Unix System Services (Open Edition).
* For example, ucnv_open("ibm-1047,swaplfnl", &errorCode);
* See convrtrs.txt.
*
* @see ucnv_open
* @stable ICU 2.4
*/
#define UCNV_SWAP_LFNL_OPTION_STRING ",swaplfnl"

/**
* Do a fuzzy compare of two converter/alias names.
* The comparison is case-insensitive, ignores leading zeroes if they are not
* followed by further digits, and ignores all but letters and digits.
* Thus the strings "UTF-8", "utf_8", "u*T@f08" and "Utf 8" are exactly equivalent.
* See section 1.4, Charset Alias Matching in Unicode Technical Standard #22
* at http://www.unicode.org/reports/tr22/
*
* @param name1 a converter name or alias, zero-terminated
* @param name2 a converter name or alias, zero-terminated
* @return 0 if the names match, or a negative value if the name1
* lexically precedes name2, or a positive value if the name1
* lexically follows name2.
* @stable ICU 2.0
*/
U_CAPI int U_EXPORT2
ucnv_compareNames(const char *name1, const char *name2);


/**
* Creates a UConverter object with the name of a coded character set specified as a C string.
* The actual name will be resolved with the alias file
* using a case-insensitive string comparison that ignores
* leading zeroes and all non-alphanumeric characters.
* E.g., the names "UTF8", "utf-8", "u*T@f08" and "Utf 8" are all equivalent.
* (See also ucnv_compareNames().)
* If <code>NULL</code> is passed for the converter name, it will create one with the
* getDefaultName return value.
*
* <p>A converter name for ICU 1.5 and above may contain options
* like a locale specification to control the specific behavior of
* the newly instantiated converter.
* The meaning of the options depends on the particular converter.
* If an option is not defined for or recognized by a given converter, then it is ignored.</p>
*
* <p>Options are appended to the converter name string, with a
* <code>UCNV_OPTION_SEP_CHAR</code> between the name and the first option and
* also between adjacent options.</p>
*
* <p>If the alias is ambiguous, then the preferred converter is used
* and the status is set to U_AMBIGUOUS_ALIAS_WARNING.</p>
*
* <p>The conversion behavior and names can vary between platforms. ICU may
* convert some characters differently from other platforms. Details on this topic
* are in the <a href="https://unicode-org.github.io/icu/userguide/conversion/">User
* Guide</a>. Aliases starting with a "cp" prefix have no specific meaning
* other than its an alias starting with the letters "cp". Please do not
* associate any meaning to these aliases.</p>
*
* @param converterName Name of the coded character set table.
*          This may have options appended to the string.
*          IANA alias character set names, IBM CCSIDs starting with "ibm-",
*          Windows codepage numbers starting with "windows-" are frequently
*          used for this parameter. See ucnv_getAvailableName and
*          ucnv_getAlias for a complete list that is available.
*          If this parameter is NULL, the default converter will be used.
* @param err outgoing error status <TT>U_MEMORY_ALLOCATION_ERROR, U_FILE_ACCESS_ERROR</TT>
* @return the created Unicode converter object, or <TT>NULL</TT> if an error occurred
* @see ucnv_openU
* @see ucnv_openCCSID
* @see ucnv_getAvailableName
* @see ucnv_getAlias
* @see ucnv_getDefaultName
* @see ucnv_close
* @see ucnv_compareNames
* @stable ICU 2.0
*/
U_CAPI UConverter* U_EXPORT2
ucnv_open(const char *converterName, UErrorCode *err);


/**
* Creates a Unicode converter with the names specified as unicode string.
* The name should be limited to the ASCII-7 alphanumerics range.
* The actual name will be resolved with the alias file
* using a case-insensitive string comparison that ignores
* leading zeroes and all non-alphanumeric characters.
* E.g., the names "UTF8", "utf-8", "u*T@f08" and "Utf 8" are all equivalent.
* (See also ucnv_compareNames().)
* If <TT>NULL</TT> is passed for the converter name, it will create
* one with the ucnv_getDefaultName() return value.
* If the alias is ambiguous, then the preferred converter is used
* and the status is set to U_AMBIGUOUS_ALIAS_WARNING.
*
* <p>See ucnv_open for the complete details</p>
* @param name Name of the UConverter table in a zero terminated
*        Unicode string
* @param err outgoing error status <TT>U_MEMORY_ALLOCATION_ERROR,
*        U_FILE_ACCESS_ERROR</TT>
* @return the created Unicode converter object, or <TT>NULL</TT> if an
*        error occurred
* @see ucnv_open
* @see ucnv_openCCSID
* @see ucnv_close
* @see ucnv_compareNames
* @stable ICU 2.0
*/
U_CAPI UConverter* U_EXPORT2
ucnv_openU(const UChar *name,
          UErrorCode *err);

/**
* Creates a UConverter object from a CCSID number and platform pair.
* Note that the usefulness of this function is limited to platforms with numeric
* encoding IDs. Only IBM and Microsoft platforms use numeric (16-bit) identifiers for
* encodings.
*
* In addition, IBM CCSIDs and Unicode conversion tables are not 1:1 related.
* For many IBM CCSIDs there are multiple (up to six) Unicode conversion tables, and
* for some Unicode conversion tables there are multiple CCSIDs.
* Some "alternate" Unicode conversion tables are provided by the
* IBM CDRA conversion table registry.
* The most prominent example of a systematic modification of conversion tables that is
* not provided in the form of conversion table files in the repository is
* that S/390 Unix System Services swaps the codes for Line Feed and New Line in all
* EBCDIC codepages, which requires such a swap in the Unicode conversion tables as well.
*
* Only IBM default conversion tables are accessible with ucnv_openCCSID().
* ucnv_getCCSID() will return the same CCSID for all conversion tables that are associated
* with that CCSID.
*
* Currently, the only "platform" supported in the ICU converter API is UCNV_IBM.
*
* In summary, the use of CCSIDs and the associated API functions is not recommended.
*
* In order to open a converter with the default IBM CDRA Unicode conversion table,
* you can use this function or use the prefix "ibm-":
* \code
*     char name[20];
*     sprintf(name, "ibm-%hu", ccsid);
*     cnv=ucnv_open(name, &errorCode);
* \endcode
*
* In order to open a converter with the IBM S/390 Unix System Services variant
* of a Unicode/EBCDIC conversion table,
* you can use the prefix "ibm-" together with the option string UCNV_SWAP_LFNL_OPTION_STRING:
* \code
*     char name[20];
*     sprintf(name, "ibm-%hu" UCNV_SWAP_LFNL_OPTION_STRING, ccsid);
*     cnv=ucnv_open(name, &errorCode);
* \endcode
*
* In order to open a converter from a Microsoft codepage number, use the prefix "cp":
* \code
*     char name[20];
*     sprintf(name, "cp%hu", codepageID);
*     cnv=ucnv_open(name, &errorCode);
* \endcode
*
* If the alias is ambiguous, then the preferred converter is used
* and the status is set to U_AMBIGUOUS_ALIAS_WARNING.
*
* @param codepage codepage number to create
* @param platform the platform in which the codepage number exists
* @param err error status <TT>U_MEMORY_ALLOCATION_ERROR, U_FILE_ACCESS_ERROR</TT>
* @return the created Unicode converter object, or <TT>NULL</TT> if an error
*   occurred.
* @see ucnv_open
* @see ucnv_openU
* @see ucnv_close
* @see ucnv_getCCSID
* @see ucnv_getPlatform
* @see UConverterPlatform
* @stable ICU 2.0
*/
U_CAPI UConverter* U_EXPORT2
ucnv_openCCSID(int32_t codepage,
              UConverterPlatform platform,
              UErrorCode * err);

/**
* <p>Creates a UConverter object specified from a packageName and a converterName.</p>
*
* <p>The packageName and converterName must point to an ICU udata object, as defined by
*   <code> udata_open( packageName, "cnv", converterName, err) </code> or equivalent.
* Typically, packageName will refer to a (.dat) file, or to a package registered with
* udata_setAppData(). Using a full file or directory pathname for packageName is deprecated.</p>
*
* <p>The name will NOT be looked up in the alias mechanism, nor will the converter be
* stored in the converter cache or the alias table. The only way to open further converters
* is call this function multiple times, or use the ucnv_clone() function to clone a
* 'primary' converter.</p>
*
* <p>A future version of ICU may add alias table lookups and/or caching
* to this function.</p>
*
* <p>Example Use:
*      <code>cnv = ucnv_openPackage("myapp", "myconverter", &err);</code>
* </p>
*
* @param packageName name of the package (equivalent to 'path' in udata_open() call)
* @param converterName name of the data item to be used, without suffix.
* @param err outgoing error status <TT>U_MEMORY_ALLOCATION_ERROR, U_FILE_ACCESS_ERROR</TT>
* @return the created Unicode converter object, or <TT>NULL</TT> if an error occurred
* @see udata_open
* @see ucnv_open
* @see ucnv_clone
* @see ucnv_close
* @stable ICU 2.2
*/
U_CAPI UConverter* U_EXPORT2
ucnv_openPackage(const char *packageName, const char *converterName, UErrorCode *err);

/**
* Thread safe converter cloning operation.
*
* You must ucnv_close() the clone.
*
* @param cnv converter to be cloned
* @param status to indicate whether the operation went on smoothly or there were errors
* @return pointer to the new clone
* @stable ICU 71
*/
U_CAPI UConverter* U_EXPORT2 ucnv_clone(const UConverter *cnv, UErrorCode *status);

#ifndef U_HIDE_DEPRECATED_API

/**
* Thread safe converter cloning operation.
* For most efficient operation, pass in a stackBuffer (and a *pBufferSize)
* with at least U_CNV_SAFECLONE_BUFFERSIZE bytes of space.
* If the buffer size is sufficient, then the clone will use the stack buffer;
* otherwise, it will be allocated, and *pBufferSize will indicate
* the actual size. (This should not occur with U_CNV_SAFECLONE_BUFFERSIZE.)
*
* You must ucnv_close() the clone in any case.
*
* If *pBufferSize==0, (regardless of whether stackBuffer==NULL or not)
* then *pBufferSize will be changed to a sufficient size
* for cloning this converter,
* without actually cloning the converter ("pure pre-flighting").
*
* If *pBufferSize is greater than zero but not large enough for a stack-based
* clone, then the converter is cloned using newly allocated memory
* and *pBufferSize is changed to the necessary size.
*
* If the converter clone fits into the stack buffer but the stack buffer is not
* sufficiently aligned for the clone, then the clone will use an
* adjusted pointer and use an accordingly smaller buffer size.
*
* @param cnv converter to be cloned
* @param stackBuffer <em>Deprecated functionality as of ICU 52, use NULL.</em><br>
*  user allocated space for the new clone. If NULL new memory will be allocated.
*  If buffer is not large enough, new memory will be allocated.
*  Clients can use the U_CNV_SAFECLONE_BUFFERSIZE. This will probably be enough to avoid memory allocations.
* @param pBufferSize <em>Deprecated functionality as of ICU 52, use NULL or 1.</em><br>
*  pointer to size of allocated space.
* @param status to indicate whether the operation went on smoothly or there were errors
*  An informational status value, U_SAFECLONE_ALLOCATED_WARNING,
*  is used if pBufferSize != NULL and any allocations were necessary
*  However, it is better to check if *pBufferSize grew for checking for
*  allocations because warning codes can be overridden by subsequent
*  function calls.
* @return pointer to the new clone
* @deprecated ICU 71 Use ucnv_clone() instead.
*/
U_DEPRECATED UConverter * U_EXPORT2
ucnv_safeClone(const UConverter *cnv,
              void             *stackBuffer,
              int32_t          *pBufferSize,
              UErrorCode       *status);

/**
* \def U_CNV_SAFECLONE_BUFFERSIZE
* Definition of a buffer size that is designed to be large enough for
* converters to be cloned with ucnv_safeClone().
* @deprecated ICU 52. Do not rely on ucnv_safeClone() cloning into any provided buffer.
*/
#define U_CNV_SAFECLONE_BUFFERSIZE  1024

#endif /* U_HIDE_DEPRECATED_API */

/**
* Deletes the unicode converter and releases resources associated
* with just this instance.
* Does not free up shared converter tables.
*
* @param converter the converter object to be deleted
* @see ucnv_open
* @see ucnv_openU
* @see ucnv_openCCSID
* @stable ICU 2.0
*/
U_CAPI void  U_EXPORT2
ucnv_close(UConverter * converter);

#if U_SHOW_CPLUSPLUS_API

U_NAMESPACE_BEGIN

/**
* \class LocalUConverterPointer
* "Smart pointer" class, closes a UConverter via ucnv_close().
* For most methods see the LocalPointerBase base class.
*
* @see LocalPointerBase
* @see LocalPointer
* @stable ICU 4.4
*/
U_DEFINE_LOCAL_OPEN_POINTER(LocalUConverterPointer, UConverter, ucnv_close);

U_NAMESPACE_END

#endif

/**
* Fills in the output parameter, subChars, with the substitution characters
* as multiple bytes.
* If ucnv_setSubstString() set a Unicode string because the converter is
* stateful, then subChars will be an empty string.
*
* @param converter the Unicode converter
* @param subChars the substitution characters
* @param len on input the capacity of subChars, on output the number
* of bytes copied to it
* @param  err the outgoing error status code.
* If the substitution character array is too small, an
* <TT>U_INDEX_OUTOFBOUNDS_ERROR</TT> will be returned.
* @see ucnv_setSubstString
* @see ucnv_setSubstChars
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ucnv_getSubstChars(const UConverter *converter,
                  char *subChars,
                  int8_t *len,
                  UErrorCode *err);

/**
* Sets the substitution chars when converting from unicode to a codepage. The
* substitution is specified as a string of 1-4 bytes, and may contain
* <TT>NULL</TT> bytes.
* The subChars must represent a single character. The caller needs to know the
* byte sequence of a valid character in the converter's charset.
* For some converters, for example some ISO 2022 variants, only single-byte
* substitution characters may be supported.
* The newer ucnv_setSubstString() function relaxes these limitations.
*
* @param converter the Unicode converter
* @param subChars the substitution character byte sequence we want set
* @param len the number of bytes in subChars
* @param err the error status code.  <TT>U_INDEX_OUTOFBOUNDS_ERROR </TT> if
* len is bigger than the maximum number of bytes allowed in subchars
* @see ucnv_setSubstString
* @see ucnv_getSubstChars
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ucnv_setSubstChars(UConverter *converter,
                  const char *subChars,
                  int8_t len,
                  UErrorCode *err);

/**
* Set a substitution string for converting from Unicode to a charset.
* The caller need not know the charset byte sequence for each charset.
*
* Unlike ucnv_setSubstChars() which is designed to set a charset byte sequence
* for a single character, this function takes a Unicode string with
* zero, one or more characters, and immediately verifies that the string can be
* converted to the charset.
* If not, or if the result is too long (more than 32 bytes as of ICU 3.6),
* then the function returns with an error accordingly.
*
* Also unlike ucnv_setSubstChars(), this function works for stateful charsets
* by converting on the fly at the point of substitution rather than setting
* a fixed byte sequence.
*
* @param cnv The UConverter object.
* @param s The Unicode string.
* @param length The number of UChars in s, or -1 for a NUL-terminated string.
* @param err Pointer to a standard ICU error code. Its input value must
*            pass the U_SUCCESS() test, or else the function returns
*            immediately. Check for U_FAILURE() on output or use with
*            function chaining. (See User Guide for details.)
*
* @see ucnv_setSubstChars
* @see ucnv_getSubstChars
* @stable ICU 3.6
*/
U_CAPI void U_EXPORT2
ucnv_setSubstString(UConverter *cnv,
                   const UChar *s,
                   int32_t length,
                   UErrorCode *err);

/**
* Fills in the output parameter, errBytes, with the error characters from the
* last failing conversion.
*
* @param converter the Unicode converter
* @param errBytes the codepage bytes which were in error
* @param len on input the capacity of errBytes, on output the number of
*  bytes which were copied to it
* @param err the error status code.
* If the substitution character array is too small, an
* <TT>U_INDEX_OUTOFBOUNDS_ERROR</TT> will be returned.
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ucnv_getInvalidChars(const UConverter *converter,
                    char *errBytes,
                    int8_t *len,
                    UErrorCode *err);

/**
* Fills in the output parameter, errChars, with the error characters from the
* last failing conversion.
*
* @param converter the Unicode converter
* @param errUChars the UChars which were in error
* @param len on input the capacity of errUChars, on output the number of
*  UChars which were copied to it
* @param err the error status code.
* If the substitution character array is too small, an
* <TT>U_INDEX_OUTOFBOUNDS_ERROR</TT> will be returned.
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ucnv_getInvalidUChars(const UConverter *converter,
                     UChar *errUChars,
                     int8_t *len,
                     UErrorCode *err);

/**
* Resets the state of a converter to the default state. This is used
* in the case of an error, to restart a conversion from a known default state.
* It will also empty the internal output buffers.
* @param converter the Unicode converter
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ucnv_reset(UConverter *converter);

/**
* Resets the to-Unicode part of a converter state to the default state.
* This is used in the case of an error to restart a conversion to
* Unicode to a known default state. It will also empty the internal
* output buffers used for the conversion to Unicode codepoints.
* @param converter the Unicode converter
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ucnv_resetToUnicode(UConverter *converter);

/**
* Resets the from-Unicode part of a converter state to the default state.
* This is used in the case of an error to restart a conversion from
* Unicode to a known default state. It will also empty the internal output
* buffers used for the conversion from Unicode codepoints.
* @param converter the Unicode converter
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ucnv_resetFromUnicode(UConverter *converter);

/**
* Returns the maximum number of bytes that are output per UChar in conversion
* from Unicode using this converter.
* The returned number can be used with UCNV_GET_MAX_BYTES_FOR_STRING
* to calculate the size of a target buffer for conversion from Unicode.
*
* Note: Before ICU 2.8, this function did not return reliable numbers for
* some stateful converters (EBCDIC_STATEFUL, ISO-2022) and LMBCS.
*
* This number may not be the same as the maximum number of bytes per
* "conversion unit". In other words, it may not be the intuitively expected
* number of bytes per character that would be published for a charset,
* and may not fulfill any other purpose than the allocation of an output
* buffer of guaranteed sufficient size for a given input length and converter.
*
* Examples for special cases that are taken into account:
* - Supplementary code points may convert to more bytes than BMP code points.
*   This function returns bytes per UChar (UTF-16 code unit), not per
*   Unicode code point, for efficient buffer allocation.
* - State-shifting output (SI/SO, escapes, etc.) from stateful converters.
* - When m input UChars are converted to n output bytes, then the maximum m/n
*   is taken into account.
*
* The number returned here does not take into account
* (see UCNV_GET_MAX_BYTES_FOR_STRING):
* - callbacks which output more than one charset character sequence per call,
*   like escape callbacks
* - initial and final non-character bytes that are output by some converters
*   (automatic BOMs, initial escape sequence, final SI, etc.)
*
* Examples for returned values:
* - SBCS charsets: 1
* - Shift-JIS: 2
* - UTF-16: 2 (2 per BMP, 4 per surrogate _pair_, BOM not counted)
* - UTF-8: 3 (3 per BMP, 4 per surrogate _pair_)
* - EBCDIC_STATEFUL (EBCDIC mixed SBCS/DBCS): 3 (SO + DBCS)
* - ISO-2022: 3 (always outputs UTF-8)
* - ISO-2022-JP: 6 (4-byte escape sequences + DBCS)
* - ISO-2022-CN: 8 (4-byte designator sequences + 2-byte SS2/SS3 + DBCS)
*
* @param converter The Unicode converter.
* @return The maximum number of bytes per UChar (16 bit code unit)
*    that are output by ucnv_fromUnicode(),
*    to be used together with UCNV_GET_MAX_BYTES_FOR_STRING
*    for buffer allocation.
*
* @see UCNV_GET_MAX_BYTES_FOR_STRING
* @see ucnv_getMinCharSize
* @stable ICU 2.0
*/
U_CAPI int8_t U_EXPORT2
ucnv_getMaxCharSize(const UConverter *converter);

/**
* Calculates the size of a buffer for conversion from Unicode to a charset.
* The calculated size is guaranteed to be sufficient for this conversion.
*
* It takes into account initial and final non-character bytes that are output
* by some converters.
* It does not take into account callbacks which output more than one charset
* character sequence per call, like escape callbacks.
* The default (substitution) callback only outputs one charset character sequence.
*
* @param length Number of UChars to be converted.
* @param maxCharSize Return value from ucnv_getMaxCharSize() for the converter
*                    that will be used.
* @return Size of a buffer that will be large enough to hold the output bytes of
*         converting length UChars with the converter that returned the maxCharSize.
*
* @see ucnv_getMaxCharSize
* @stable ICU 2.8
*/
#define UCNV_GET_MAX_BYTES_FOR_STRING(length, maxCharSize) \
    (((int32_t)(length)+10)*(int32_t)(maxCharSize))

/**
* Returns the minimum byte length (per codepoint) for characters in this codepage.
* This is usually either 1 or 2.
* @param converter the Unicode converter
* @return the minimum number of bytes per codepoint allowed by this particular converter
* @see ucnv_getMaxCharSize
* @stable ICU 2.0
*/
U_CAPI int8_t U_EXPORT2
ucnv_getMinCharSize(const UConverter *converter);

/**
* Returns the display name of the converter passed in based on the Locale
* passed in. If the locale contains no display name, the internal ASCII
* name will be filled in.
*
* @param converter the Unicode converter.
* @param displayLocale is the specific Locale we want to localized for
* @param displayName user provided buffer to be filled in
* @param displayNameCapacity size of displayName Buffer
* @param err error status code
* @return displayNameLength number of UChar needed in displayName
* @see ucnv_getName
* @stable ICU 2.0
*/
U_CAPI int32_t U_EXPORT2
ucnv_getDisplayName(const UConverter *converter,
                   const char *displayLocale,
                   UChar *displayName,
                   int32_t displayNameCapacity,
                   UErrorCode *err);

/**
* Gets the internal, canonical name of the converter (zero-terminated).
* The lifetime of the returned string will be that of the converter
* passed to this function.
* @param converter the Unicode converter
* @param err UErrorCode status
* @return the internal name of the converter
* @see ucnv_getDisplayName
* @stable ICU 2.0
*/
U_CAPI const char * U_EXPORT2
ucnv_getName(const UConverter *converter, UErrorCode *err);

/**
* Gets a codepage number associated with the converter. This is not guaranteed
* to be the one used to create the converter. Some converters do not represent
* platform registered codepages and return zero for the codepage number.
* The error code fill-in parameter indicates if the codepage number
* is available.
* Does not check if the converter is <TT>NULL</TT> or if converter's data
* table is <TT>NULL</TT>.
*
* Important: The use of CCSIDs is not recommended because it is limited
* to only two platforms in principle and only one (UCNV_IBM) in the current
* ICU converter API.
* Also, CCSIDs are insufficient to identify IBM Unicode conversion tables precisely.
* For more details see ucnv_openCCSID().
*
* @param converter the Unicode converter
* @param err the error status code.
* @return If any error occurs, -1 will be returned otherwise, the codepage number
* will be returned
* @see ucnv_openCCSID
* @see ucnv_getPlatform
* @stable ICU 2.0
*/
U_CAPI int32_t U_EXPORT2
ucnv_getCCSID(const UConverter *converter,
             UErrorCode *err);

/**
* Gets a codepage platform associated with the converter. Currently,
* only <TT>UCNV_IBM</TT> will be returned.
* Does not test if the converter is <TT>NULL</TT> or if converter's data
* table is <TT>NULL</TT>.
* @param converter the Unicode converter
* @param err the error status code.
* @return The codepage platform
* @stable ICU 2.0
*/
U_CAPI UConverterPlatform U_EXPORT2
ucnv_getPlatform(const UConverter *converter,
                UErrorCode *err);

/**
* Gets the type of the converter
* e.g. SBCS, MBCS, DBCS, UTF8, UTF16_BE, UTF16_LE, ISO_2022,
* EBCDIC_STATEFUL, LATIN_1
* @param converter a valid, opened converter
* @return the type of the converter
* @stable ICU 2.0
*/
U_CAPI UConverterType U_EXPORT2
ucnv_getType(const UConverter * converter);

/**
* Gets the "starter" (lead) bytes for converters of type MBCS.
* Will fill in an <TT>U_ILLEGAL_ARGUMENT_ERROR</TT> if converter passed in
* is not MBCS. Fills in an array of type UBool, with the value of the byte
* as offset to the array. For example, if (starters[0x20] == true) at return,
* it means that the byte 0x20 is a starter byte in this converter.
* Context pointers are always owned by the caller.
*
* @param converter a valid, opened converter of type MBCS
* @param starters an array of size 256 to be filled in
* @param err error status, <TT>U_ILLEGAL_ARGUMENT_ERROR</TT> if the
* converter is not a type which can return starters.
* @see ucnv_getType
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ucnv_getStarters(const UConverter* converter,
                UBool starters[256],
                UErrorCode* err);


/**
* Selectors for Unicode sets that can be returned by ucnv_getUnicodeSet().
* @see ucnv_getUnicodeSet
* @stable ICU 2.6
*/
typedef enum UConverterUnicodeSet {
   /** Select the set of roundtrippable Unicode code points. @stable ICU 2.6 */
   UCNV_ROUNDTRIP_SET,
   /** Select the set of Unicode code points with roundtrip or fallback mappings. @stable ICU 4.0 */
   UCNV_ROUNDTRIP_AND_FALLBACK_SET,
#ifndef U_HIDE_DEPRECATED_API
   /**
    * Number of UConverterUnicodeSet selectors.
    * @deprecated ICU 58 The numeric value may change over time, see ICU ticket #12420.
    */
   UCNV_SET_COUNT
#endif  // U_HIDE_DEPRECATED_API
} UConverterUnicodeSet;


/**
* Returns the set of Unicode code points that can be converted by an ICU converter.
*
* Returns one of several kinds of set:
*
* 1. UCNV_ROUNDTRIP_SET
*
* The set of all Unicode code points that can be roundtrip-converted
* (converted without any data loss) with the converter (ucnv_fromUnicode()).
* This set will not include code points that have fallback mappings
* or are only the result of reverse fallback mappings.
* This set will also not include PUA code points with fallbacks, although
* ucnv_fromUnicode() will always uses those mappings despite ucnv_setFallback().
* See UTR #22 "Character Mapping Markup Language"
* at http://www.unicode.org/reports/tr22/
*
* This is useful for example for
* - checking that a string or document can be roundtrip-converted with a converter,
*   without/before actually performing the conversion
* - testing if a converter can be used for text for typical text for a certain locale,
*   by comparing its roundtrip set with the set of ExemplarCharacters from
*   ICU's locale data or other sources
*
* 2. UCNV_ROUNDTRIP_AND_FALLBACK_SET
*
* The set of all Unicode code points that can be converted with the converter (ucnv_fromUnicode())
* when fallbacks are turned on (see ucnv_setFallback()).
* This set includes all code points with roundtrips and fallbacks (but not reverse fallbacks).
*
* In the future, there may be more UConverterUnicodeSet choices to select
* sets with different properties.
*
* @param cnv The converter for which a set is requested.
* @param setFillIn A valid USet *. It will be cleared by this function before
*            the converter's specific set is filled into the USet.
* @param whichSet A UConverterUnicodeSet selector;
*              currently UCNV_ROUNDTRIP_SET is the only supported value.
* @param pErrorCode ICU error code in/out parameter.
*                   Must fulfill U_SUCCESS before the function call.
*
* @see UConverterUnicodeSet
* @see uset_open
* @see uset_close
* @stable ICU 2.6
*/
U_CAPI void U_EXPORT2
ucnv_getUnicodeSet(const UConverter *cnv,
                  USet *setFillIn,
                  UConverterUnicodeSet whichSet,
                  UErrorCode *pErrorCode);

/**
* Gets the current callback function used by the converter when an illegal
*  or invalid codepage sequence is found.
* Context pointers are always owned by the caller.
*
* @param converter the unicode converter
* @param action fillin: returns the callback function pointer
* @param context fillin: returns the callback's private void* context
* @see ucnv_setToUCallBack
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ucnv_getToUCallBack (const UConverter * converter,
                    UConverterToUCallback *action,
                    const void **context);

/**
* Gets the current callback function used by the converter when illegal
* or invalid Unicode sequence is found.
* Context pointers are always owned by the caller.
*
* @param converter the unicode converter
* @param action fillin: returns the callback function pointer
* @param context fillin: returns the callback's private void* context
* @see ucnv_setFromUCallBack
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ucnv_getFromUCallBack (const UConverter * converter,
                      UConverterFromUCallback *action,
                      const void **context);

/**
* Changes the callback function used by the converter when
* an illegal or invalid sequence is found.
* Context pointers are always owned by the caller.
* Predefined actions and contexts can be found in the ucnv_err.h header.
*
* @param converter the unicode converter
* @param newAction the new callback function
* @param newContext the new toUnicode callback context pointer. This can be NULL.
* @param oldAction fillin: returns the old callback function pointer. This can be NULL.
* @param oldContext fillin: returns the old callback's private void* context. This can be NULL.
* @param err The error code status
* @see ucnv_getToUCallBack
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ucnv_setToUCallBack (UConverter * converter,
                    UConverterToUCallback newAction,
                    const void* newContext,
                    UConverterToUCallback *oldAction,
                    const void** oldContext,
                    UErrorCode * err);

/**
* Changes the current callback function used by the converter when
* an illegal or invalid sequence is found.
* Context pointers are always owned by the caller.
* Predefined actions and contexts can be found in the ucnv_err.h header.
*
* @param converter the unicode converter
* @param newAction the new callback function
* @param newContext the new fromUnicode callback context pointer. This can be NULL.
* @param oldAction fillin: returns the old callback function pointer. This can be NULL.
* @param oldContext fillin: returns the old callback's private void* context. This can be NULL.
* @param err The error code status
* @see ucnv_getFromUCallBack
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ucnv_setFromUCallBack (UConverter * converter,
                      UConverterFromUCallback newAction,
                      const void *newContext,
                      UConverterFromUCallback *oldAction,
                      const void **oldContext,
                      UErrorCode * err);

/**
* Converts an array of unicode characters to an array of codepage
* characters. This function is optimized for converting a continuous
* stream of data in buffer-sized chunks, where the entire source and
* target does not fit in available buffers.
*
* The source pointer is an in/out parameter. It starts out pointing where the
* conversion is to begin, and ends up pointing after the last UChar consumed.
*
* Target similarly starts out pointer at the first available byte in the output
* buffer, and ends up pointing after the last byte written to the output.
*
* The converter always attempts to consume the entire source buffer, unless
* (1.) the target buffer is full, or (2.) a failing error is returned from the
* current callback function.  When a successful error status has been
* returned, it means that all of the source buffer has been
*  consumed. At that point, the caller should reset the source and
*  sourceLimit pointers to point to the next chunk.
*
* At the end of the stream (flush==true), the input is completely consumed
* when *source==sourceLimit and no error code is set.
* The converter object is then automatically reset by this function.
* (This means that a converter need not be reset explicitly between data
* streams if it finishes the previous stream without errors.)
*
* This is a <I>stateful</I> conversion. Additionally, even when all source data has
* been consumed, some data may be in the converters' internal state.
* Call this function repeatedly, updating the target pointers with
* the next empty chunk of target in case of a
* <TT>U_BUFFER_OVERFLOW_ERROR</TT>, and updating the source  pointers
*  with the next chunk of source when a successful error status is
* returned, until there are no more chunks of source data.
* @param converter the Unicode converter
* @param target I/O parameter. Input : Points to the beginning of the buffer to copy
*  codepage characters to. Output : points to after the last codepage character copied
*  to <TT>target</TT>.
* @param targetLimit the pointer just after last of the <TT>target</TT> buffer
* @param source I/O parameter, pointer to pointer to the source Unicode character buffer.
* @param sourceLimit the pointer just after the last of the source buffer
* @param offsets if NULL is passed, nothing will happen to it, otherwise it needs to have the same number
* of allocated cells as <TT>target</TT>. Will fill in offsets from target to source pointer
* e.g: <TT>offsets[3]</TT> is equal to 6, it means that the <TT>target[3]</TT> was a result of transcoding <TT>source[6]</TT>
* For output data carried across calls, and other data without a specific source character
* (such as from escape sequences or callbacks)  -1 will be placed for offsets.
* @param flush set to <TT>true</TT> if the current source buffer is the last available
* chunk of the source, <TT>false</TT> otherwise. Note that if a failing status is returned,
* this function may have to be called multiple times with flush set to <TT>true</TT> until
* the source buffer is consumed.
* @param err the error status.  <TT>U_ILLEGAL_ARGUMENT_ERROR</TT> will be set if the
* converter is <TT>NULL</TT>.
* <code>U_BUFFER_OVERFLOW_ERROR</code> will be set if the target is full and there is
* still data to be written to the target.
* @see ucnv_fromUChars
* @see ucnv_convert
* @see ucnv_getMinCharSize
* @see ucnv_setToUCallBack
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ucnv_fromUnicode (UConverter * converter,
                 char **target,
                 const char *targetLimit,
                 const UChar ** source,
                 const UChar * sourceLimit,
                 int32_t* offsets,
                 UBool flush,
                 UErrorCode * err);

/**
* Converts a buffer of codepage bytes into an array of unicode UChars
* characters. This function is optimized for converting a continuous
* stream of data in buffer-sized chunks, where the entire source and
* target does not fit in available buffers.
*
* The source pointer is an in/out parameter. It starts out pointing where the
* conversion is to begin, and ends up pointing after the last byte of source consumed.
*
* Target similarly starts out pointer at the first available UChar in the output
* buffer, and ends up pointing after the last UChar written to the output.
* It does NOT necessarily keep UChar sequences together.
*
* The converter always attempts to consume the entire source buffer, unless
* (1.) the target buffer is full, or (2.) a failing error is returned from the
* current callback function.  When a successful error status has been
* returned, it means that all of the source buffer has been
*  consumed. At that point, the caller should reset the source and
*  sourceLimit pointers to point to the next chunk.
*
* At the end of the stream (flush==true), the input is completely consumed
* when *source==sourceLimit and no error code is set
* The converter object is then automatically reset by this function.
* (This means that a converter need not be reset explicitly between data
* streams if it finishes the previous stream without errors.)
*
* This is a <I>stateful</I> conversion. Additionally, even when all source data has
* been consumed, some data may be in the converters' internal state.
* Call this function repeatedly, updating the target pointers with
* the next empty chunk of target in case of a
* <TT>U_BUFFER_OVERFLOW_ERROR</TT>, and updating the source  pointers
*  with the next chunk of source when a successful error status is
* returned, until there are no more chunks of source data.
* @param converter the Unicode converter
* @param target I/O parameter. Input : Points to the beginning of the buffer to copy
*  UChars into. Output : points to after the last UChar copied.
* @param targetLimit the pointer just after the end of the <TT>target</TT> buffer
* @param source I/O parameter, pointer to pointer to the source codepage buffer.
* @param sourceLimit the pointer to the byte after the end of the source buffer
* @param offsets if NULL is passed, nothing will happen to it, otherwise it needs to have the same number
* of allocated cells as <TT>target</TT>. Will fill in offsets from target to source pointer
* e.g: <TT>offsets[3]</TT> is equal to 6, it means that the <TT>target[3]</TT> was a result of transcoding <TT>source[6]</TT>
* For output data carried across calls, and other data without a specific source character
* (such as from escape sequences or callbacks)  -1 will be placed for offsets.
* @param flush set to <TT>true</TT> if the current source buffer is the last available
* chunk of the source, <TT>false</TT> otherwise. Note that if a failing status is returned,
* this function may have to be called multiple times with flush set to <TT>true</TT> until
* the source buffer is consumed.
* @param err the error status.  <TT>U_ILLEGAL_ARGUMENT_ERROR</TT> will be set if the
* converter is <TT>NULL</TT>.
* <code>U_BUFFER_OVERFLOW_ERROR</code> will be set if the target is full and there is
* still data to be written to the target.
* @see ucnv_fromUChars
* @see ucnv_convert
* @see ucnv_getMinCharSize
* @see ucnv_setFromUCallBack
* @see ucnv_getNextUChar
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ucnv_toUnicode(UConverter *converter,
              UChar **target,
              const UChar *targetLimit,
              const char **source,
              const char *sourceLimit,
              int32_t *offsets,
              UBool flush,
              UErrorCode *err);

/**
* Convert the Unicode string into a codepage string using an existing UConverter.
* The output string is NUL-terminated if possible.
*
* This function is a more convenient but less powerful version of ucnv_fromUnicode().
* It is only useful for whole strings, not for streaming conversion.
*
* The maximum output buffer capacity required (barring output from callbacks) will be
* UCNV_GET_MAX_BYTES_FOR_STRING(srcLength, ucnv_getMaxCharSize(cnv)).
*
* @param cnv the converter object to be used (ucnv_resetFromUnicode() will be called)
* @param src the input Unicode string
* @param srcLength the input string length, or -1 if NUL-terminated
* @param dest destination string buffer, can be NULL if destCapacity==0
* @param destCapacity the number of chars available at dest
* @param pErrorCode normal ICU error code;
*                  common error codes that may be set by this function include
*                  U_BUFFER_OVERFLOW_ERROR, U_STRING_NOT_TERMINATED_WARNING,
*                  U_ILLEGAL_ARGUMENT_ERROR, and conversion errors
* @return the length of the output string, not counting the terminating NUL;
*         if the length is greater than destCapacity, then the string will not fit
*         and a buffer of the indicated length would need to be passed in
* @see ucnv_fromUnicode
* @see ucnv_convert
* @see UCNV_GET_MAX_BYTES_FOR_STRING
* @stable ICU 2.0
*/
U_CAPI int32_t U_EXPORT2
ucnv_fromUChars(UConverter *cnv,
               char *dest, int32_t destCapacity,
               const UChar *src, int32_t srcLength,
               UErrorCode *pErrorCode);

/**
* Convert the codepage string into a Unicode string using an existing UConverter.
* The output string is NUL-terminated if possible.
*
* This function is a more convenient but less powerful version of ucnv_toUnicode().
* It is only useful for whole strings, not for streaming conversion.
*
* The maximum output buffer capacity required (barring output from callbacks) will be
* 2*srcLength (each char may be converted into a surrogate pair).
*
* @param cnv the converter object to be used (ucnv_resetToUnicode() will be called)
* @param src the input codepage string
* @param srcLength the input string length, or -1 if NUL-terminated
* @param dest destination string buffer, can be NULL if destCapacity==0
* @param destCapacity the number of UChars available at dest
* @param pErrorCode normal ICU error code;
*                  common error codes that may be set by this function include
*                  U_BUFFER_OVERFLOW_ERROR, U_STRING_NOT_TERMINATED_WARNING,
*                  U_ILLEGAL_ARGUMENT_ERROR, and conversion errors
* @return the length of the output string, not counting the terminating NUL;
*         if the length is greater than destCapacity, then the string will not fit
*         and a buffer of the indicated length would need to be passed in
* @see ucnv_toUnicode
* @see ucnv_convert
* @stable ICU 2.0
*/
U_CAPI int32_t U_EXPORT2
ucnv_toUChars(UConverter *cnv,
             UChar *dest, int32_t destCapacity,
             const char *src, int32_t srcLength,
             UErrorCode *pErrorCode);

/**
* Convert a codepage buffer into Unicode one character at a time.
* The input is completely consumed when the U_INDEX_OUTOFBOUNDS_ERROR is set.
*
* Advantage compared to ucnv_toUnicode() or ucnv_toUChars():
* - Faster for small amounts of data, for most converters, e.g.,
*   US-ASCII, ISO-8859-1, UTF-8/16/32, and most "normal" charsets.
*   (For complex converters, e.g., SCSU, UTF-7 and ISO 2022 variants,
*    it uses ucnv_toUnicode() internally.)
* - Convenient.
*
* Limitations compared to ucnv_toUnicode():
* - Always assumes flush=true.
*   This makes ucnv_getNextUChar() unsuitable for "streaming" conversion,
*   that is, for where the input is supplied in multiple buffers,
*   because ucnv_getNextUChar() will assume the end of the input at the end
*   of the first buffer.
* - Does not provide offset output.
*
* It is possible to "mix" ucnv_getNextUChar() and ucnv_toUnicode() because
* ucnv_getNextUChar() uses the current state of the converter
* (unlike ucnv_toUChars() which always resets first).
* However, if ucnv_getNextUChar() is called after ucnv_toUnicode()
* stopped in the middle of a character sequence (with flush=false),
* then ucnv_getNextUChar() will always use the slower ucnv_toUnicode()
* internally until the next character boundary.
* (This is new in ICU 2.6. In earlier releases, ucnv_getNextUChar() had to
* start at a character boundary.)
*
* Instead of using ucnv_getNextUChar(), it is recommended
* to convert using ucnv_toUnicode() or ucnv_toUChars()
* and then iterate over the text using U16_NEXT() or a UCharIterator (uiter.h)
* or a C++ CharacterIterator or similar.
* This allows streaming conversion and offset output, for example.
*
* <p>Handling of surrogate pairs and supplementary-plane code points:<br>
* There are two different kinds of codepages that provide mappings for surrogate characters:
* <ul>
*   <li>Codepages like UTF-8, UTF-32, and GB 18030 provide direct representations for Unicode
*       code points U+10000-U+10ffff as well as for single surrogates U+d800-U+dfff.
*       Each valid sequence will result in exactly one returned code point.
*       If a sequence results in a single surrogate, then that will be returned
*       by itself, even if a neighboring sequence encodes the matching surrogate.</li>
*   <li>Codepages like SCSU and LMBCS (and UTF-16) provide direct representations only for BMP code points
*       including surrogates. Code points in supplementary planes are represented with
*       two sequences, each encoding a surrogate.
*       For these codepages, matching pairs of surrogates will be combined into single
*       code points for returning from this function.
*       (Note that SCSU is actually a mix of these codepage types.)</li>
* </ul></p>
*
* @param converter an open UConverter
* @param source the address of a pointer to the codepage buffer, will be
*  updated to point after the bytes consumed in the conversion call.
* @param sourceLimit points to the end of the input buffer
* @param err fills in error status (see ucnv_toUnicode)
* <code>U_INDEX_OUTOFBOUNDS_ERROR</code> will be set if the input
* is empty or does not convert to any output (e.g.: pure state-change
* codes SI/SO, escape sequences for ISO 2022,
* or if the callback did not output anything, ...).
* This function will not set a <code>U_BUFFER_OVERFLOW_ERROR</code> because
*  the "buffer" is the return code. However, there might be subsequent output
*  stored in the converter object
* that will be returned in following calls to this function.
* @return a UChar32 resulting from the partial conversion of source
* @see ucnv_toUnicode
* @see ucnv_toUChars
* @see ucnv_convert
* @stable ICU 2.0
*/
U_CAPI UChar32 U_EXPORT2
ucnv_getNextUChar(UConverter * converter,
                 const char **source,
                 const char * sourceLimit,
                 UErrorCode * err);

/**
* Convert from one external charset to another using two existing UConverters.
* Internally, two conversions - ucnv_toUnicode() and ucnv_fromUnicode() -
* are used, "pivoting" through 16-bit Unicode.
*
* Important: For streaming conversion (multiple function calls for successive
* parts of a text stream), the caller must provide a pivot buffer explicitly,
* and must preserve the pivot buffer and associated pointers from one
* call to another. (The buffer may be moved if its contents and the relative
* pointer positions are preserved.)
*
* There is a similar function, ucnv_convert(),
* which has the following limitations:
* - it takes charset names, not converter objects, so that
*   - two converters are opened for each call
*   - only single-string conversion is possible, not streaming operation
* - it does not provide enough information to find out,
*   in case of failure, whether the toUnicode or
*   the fromUnicode conversion failed
*
* By contrast, ucnv_convertEx()
* - takes UConverter parameters instead of charset names
* - fully exposes the pivot buffer for streaming conversion and complete error handling
*
* ucnv_convertEx() also provides further convenience:
* - an option to reset the converters at the beginning
*   (if reset==true, see parameters;
*    also sets *pivotTarget=*pivotSource=pivotStart)
* - allow NUL-terminated input
*   (only a single NUL byte, will not work for charsets with multi-byte NULs)
*   (if sourceLimit==NULL, see parameters)
* - terminate with a NUL on output
*   (only a single NUL byte, not useful for charsets with multi-byte NULs),
*   or set U_STRING_NOT_TERMINATED_WARNING if the output exactly fills
*   the target buffer
* - the pivot buffer can be provided internally;
*   possible only for whole-string conversion, not streaming conversion;
*   in this case, the caller will not be able to get details about where an
*   error occurred
*   (if pivotStart==NULL, see below)
*
* The function returns when one of the following is true:
* - the entire source text has been converted successfully to the target buffer
* - a target buffer overflow occurred (U_BUFFER_OVERFLOW_ERROR)
* - a conversion error occurred
*   (other U_FAILURE(), see description of pErrorCode)
*
* Limitation compared to the direct use of
* ucnv_fromUnicode() and ucnv_toUnicode():
* ucnv_convertEx() does not provide offset information.
*
* Limitation compared to ucnv_fromUChars() and ucnv_toUChars():
* ucnv_convertEx() does not support preflighting directly.
*
* Sample code for converting a single string from
* one external charset to UTF-8, ignoring the location of errors:
*
* \code
* int32_t
* myToUTF8(UConverter *cnv,
*          const char *s, int32_t length,
*          char *u8, int32_t capacity,
*          UErrorCode *pErrorCode) {
*     UConverter *utf8Cnv;
*     char *target;
*
*     if(U_FAILURE(*pErrorCode)) {
*         return 0;
*     }
*
*     utf8Cnv=myGetCachedUTF8Converter(pErrorCode);
*     if(U_FAILURE(*pErrorCode)) {
*         return 0;
*     }
*
*     if(length<0) {
*         length=strlen(s);
*     }
*     target=u8;
*     ucnv_convertEx(utf8Cnv, cnv,
*                    &target, u8+capacity,
*                    &s, s+length,
*                    NULL, NULL, NULL, NULL,
*                    true, true,
*                    pErrorCode);
*
*     myReleaseCachedUTF8Converter(utf8Cnv);
*
*     // return the output string length, but without preflighting
*     return (int32_t)(target-u8);
* }
* \endcode
*
* @param targetCnv     Output converter, used to convert from the UTF-16 pivot
*                      to the target using ucnv_fromUnicode().
* @param sourceCnv     Input converter, used to convert from the source to
*                      the UTF-16 pivot using ucnv_toUnicode().
* @param target        I/O parameter, same as for ucnv_fromUChars().
*                      Input: *target points to the beginning of the target buffer.
*                      Output: *target points to the first unit after the last char written.
* @param targetLimit   Pointer to the first unit after the target buffer.
* @param source        I/O parameter, same as for ucnv_toUChars().
*                      Input: *source points to the beginning of the source buffer.
*                      Output: *source points to the first unit after the last char read.
* @param sourceLimit   Pointer to the first unit after the source buffer.
* @param pivotStart    Pointer to the UTF-16 pivot buffer. If pivotStart==NULL,
*                      then an internal buffer is used and the other pivot
*                      arguments are ignored and can be NULL as well.
* @param pivotSource   I/O parameter, same as source in ucnv_fromUChars() for
*                      conversion from the pivot buffer to the target buffer.
* @param pivotTarget   I/O parameter, same as target in ucnv_toUChars() for
*                      conversion from the source buffer to the pivot buffer.
*                      It must be pivotStart<=*pivotSource<=*pivotTarget<=pivotLimit
*                      and pivotStart<pivotLimit (unless pivotStart==NULL).
* @param pivotLimit    Pointer to the first unit after the pivot buffer.
* @param reset         If true, then ucnv_resetToUnicode(sourceCnv) and
*                      ucnv_resetFromUnicode(targetCnv) are called, and the
*                      pivot pointers are reset (*pivotTarget=*pivotSource=pivotStart).
* @param flush         If true, indicates the end of the input.
*                      Passed directly to ucnv_toUnicode(), and carried over to
*                      ucnv_fromUnicode() when the source is empty as well.
* @param pErrorCode    ICU error code in/out parameter.
*                      Must fulfill U_SUCCESS before the function call.
*                      U_BUFFER_OVERFLOW_ERROR always refers to the target buffer
*                      because overflows into the pivot buffer are handled internally.
*                      Other conversion errors are from the source-to-pivot
*                      conversion if *pivotSource==pivotStart, otherwise from
*                      the pivot-to-target conversion.
*
* @see ucnv_convert
* @see ucnv_fromAlgorithmic
* @see ucnv_toAlgorithmic
* @see ucnv_fromUnicode
* @see ucnv_toUnicode
* @see ucnv_fromUChars
* @see ucnv_toUChars
* @stable ICU 2.6
*/
U_CAPI void U_EXPORT2
ucnv_convertEx(UConverter *targetCnv, UConverter *sourceCnv,
              char **target, const char *targetLimit,
              const char **source, const char *sourceLimit,
              UChar *pivotStart, UChar **pivotSource,
              UChar **pivotTarget, const UChar *pivotLimit,
              UBool reset, UBool flush,
              UErrorCode *pErrorCode);

/**
* Convert from one external charset to another.
* Internally, two converters are opened according to the name arguments,
* then the text is converted to and from the 16-bit Unicode "pivot"
* using ucnv_convertEx(), then the converters are closed again.
*
* This is a convenience function, not an efficient way to convert a lot of text:
* ucnv_convert()
* - takes charset names, not converter objects, so that
*   - two converters are opened for each call
*   - only single-string conversion is possible, not streaming operation
* - does not provide enough information to find out,
*   in case of failure, whether the toUnicode or
*   the fromUnicode conversion failed
* - allows NUL-terminated input
*   (only a single NUL byte, will not work for charsets with multi-byte NULs)
*   (if sourceLength==-1, see parameters)
* - terminate with a NUL on output
*   (only a single NUL byte, not useful for charsets with multi-byte NULs),
*   or set U_STRING_NOT_TERMINATED_WARNING if the output exactly fills
*   the target buffer
* - a pivot buffer is provided internally
*
* The function returns when one of the following is true:
* - the entire source text has been converted successfully to the target buffer
*   and either the target buffer is terminated with a single NUL byte
*   or the error code is set to U_STRING_NOT_TERMINATED_WARNING
* - a target buffer overflow occurred (U_BUFFER_OVERFLOW_ERROR)
*   and the full output string length is returned ("preflighting")
* - a conversion error occurred
*   (other U_FAILURE(), see description of pErrorCode)
*
* @param toConverterName   The name of the converter that is used to convert
*                          from the UTF-16 pivot buffer to the target.
* @param fromConverterName The name of the converter that is used to convert
*                          from the source to the UTF-16 pivot buffer.
* @param target            Pointer to the output buffer.
* @param targetCapacity    Capacity of the target, in bytes.
* @param source            Pointer to the input buffer.
* @param sourceLength      Length of the input text, in bytes, or -1 for NUL-terminated input.
* @param pErrorCode        ICU error code in/out parameter.
*                          Must fulfill U_SUCCESS before the function call.
* @return Length of the complete output text in bytes, even if it exceeds the targetCapacity
*         and a U_BUFFER_OVERFLOW_ERROR is set.
*
* @see ucnv_convertEx
* @see ucnv_fromAlgorithmic
* @see ucnv_toAlgorithmic
* @see ucnv_fromUnicode
* @see ucnv_toUnicode
* @see ucnv_fromUChars
* @see ucnv_toUChars
* @see ucnv_getNextUChar
* @stable ICU 2.0
*/
U_CAPI int32_t U_EXPORT2
ucnv_convert(const char *toConverterName,
            const char *fromConverterName,
            char *target,
            int32_t targetCapacity,
            const char *source,
            int32_t sourceLength,
            UErrorCode *pErrorCode);

/**
* Convert from one external charset to another.
* Internally, the text is converted to and from the 16-bit Unicode "pivot"
* using ucnv_convertEx(). ucnv_toAlgorithmic() works exactly like ucnv_convert()
* except that the two converters need not be looked up and opened completely.
*
* The source-to-pivot conversion uses the cnv converter parameter.
* The pivot-to-target conversion uses a purely algorithmic converter
* according to the specified type, e.g., UCNV_UTF8 for a UTF-8 converter.
*
* Internally, the algorithmic converter is opened and closed for each
* function call, which is more efficient than using the public ucnv_open()
* but somewhat less efficient than only resetting an existing converter
* and using ucnv_convertEx().
*
* This function is more convenient than ucnv_convertEx() for single-string
* conversions, especially when "preflighting" is desired (returning the length
* of the complete output even if it does not fit into the target buffer;
* see the User Guide Strings chapter). See ucnv_convert() for details.
*
* @param algorithmicType   UConverterType constant identifying the desired target
*                          charset as a purely algorithmic converter.
*                          Those are converters for Unicode charsets like
*                          UTF-8, BOCU-1, SCSU, UTF-7, IMAP-mailbox-name, etc.,
*                          as well as US-ASCII and ISO-8859-1.
* @param cnv               The converter that is used to convert
*                          from the source to the UTF-16 pivot buffer.
* @param target            Pointer to the output buffer.
* @param targetCapacity    Capacity of the target, in bytes.
* @param source            Pointer to the input buffer.
* @param sourceLength      Length of the input text, in bytes
* @param pErrorCode        ICU error code in/out parameter.
*                          Must fulfill U_SUCCESS before the function call.
* @return Length of the complete output text in bytes, even if it exceeds the targetCapacity
*         and a U_BUFFER_OVERFLOW_ERROR is set.
*
* @see ucnv_fromAlgorithmic
* @see ucnv_convert
* @see ucnv_convertEx
* @see ucnv_fromUnicode
* @see ucnv_toUnicode
* @see ucnv_fromUChars
* @see ucnv_toUChars
* @stable ICU 2.6
*/
U_CAPI int32_t U_EXPORT2
ucnv_toAlgorithmic(UConverterType algorithmicType,
                  UConverter *cnv,
                  char *target, int32_t targetCapacity,
                  const char *source, int32_t sourceLength,
                  UErrorCode *pErrorCode);

/**
* Convert from one external charset to another.
* Internally, the text is converted to and from the 16-bit Unicode "pivot"
* using ucnv_convertEx(). ucnv_fromAlgorithmic() works exactly like ucnv_convert()
* except that the two converters need not be looked up and opened completely.
*
* The source-to-pivot conversion uses a purely algorithmic converter
* according to the specified type, e.g., UCNV_UTF8 for a UTF-8 converter.
* The pivot-to-target conversion uses the cnv converter parameter.
*
* Internally, the algorithmic converter is opened and closed for each
* function call, which is more efficient than using the public ucnv_open()
* but somewhat less efficient than only resetting an existing converter
* and using ucnv_convertEx().
*
* This function is more convenient than ucnv_convertEx() for single-string
* conversions, especially when "preflighting" is desired (returning the length
* of the complete output even if it does not fit into the target buffer;
* see the User Guide Strings chapter). See ucnv_convert() for details.
*
* @param cnv               The converter that is used to convert
*                          from the UTF-16 pivot buffer to the target.
* @param algorithmicType   UConverterType constant identifying the desired source
*                          charset as a purely algorithmic converter.
*                          Those are converters for Unicode charsets like
*                          UTF-8, BOCU-1, SCSU, UTF-7, IMAP-mailbox-name, etc.,
*                          as well as US-ASCII and ISO-8859-1.
* @param target            Pointer to the output buffer.
* @param targetCapacity    Capacity of the target, in bytes.
* @param source            Pointer to the input buffer.
* @param sourceLength      Length of the input text, in bytes
* @param pErrorCode        ICU error code in/out parameter.
*                          Must fulfill U_SUCCESS before the function call.
* @return Length of the complete output text in bytes, even if it exceeds the targetCapacity
*         and a U_BUFFER_OVERFLOW_ERROR is set.
*
* @see ucnv_fromAlgorithmic
* @see ucnv_convert
* @see ucnv_convertEx
* @see ucnv_fromUnicode
* @see ucnv_toUnicode
* @see ucnv_fromUChars
* @see ucnv_toUChars
* @stable ICU 2.6
*/
U_CAPI int32_t U_EXPORT2
ucnv_fromAlgorithmic(UConverter *cnv,
                    UConverterType algorithmicType,
                    char *target, int32_t targetCapacity,
                    const char *source, int32_t sourceLength,
                    UErrorCode *pErrorCode);

/**
* Frees up memory occupied by unused, cached converter shared data.
*
* @return the number of cached converters successfully deleted
* @see ucnv_close
* @stable ICU 2.0
*/
U_CAPI int32_t U_EXPORT2
ucnv_flushCache(void);

/**
* Returns the number of available converters, as per the alias file.
*
* @return the number of available converters
* @see ucnv_getAvailableName
* @stable ICU 2.0
*/
U_CAPI int32_t U_EXPORT2
ucnv_countAvailable(void);

/**
* Gets the canonical converter name of the specified converter from a list of
* all available converters contained in the alias file. All converters
* in this list can be opened.
*
* @param n the index to a converter available on the system (in the range <TT>[0..ucnv_countAvailable()]</TT>)
* @return a pointer a string (library owned), or <TT>NULL</TT> if the index is out of bounds.
* @see ucnv_countAvailable
* @stable ICU 2.0
*/
U_CAPI const char* U_EXPORT2
ucnv_getAvailableName(int32_t n);

/**
* Returns a UEnumeration to enumerate all of the canonical converter
* names, as per the alias file, regardless of the ability to open each
* converter.
*
* @return A UEnumeration object for getting all the recognized canonical
*   converter names.
* @see ucnv_getAvailableName
* @see uenum_close
* @see uenum_next
* @stable ICU 2.4
*/
U_CAPI UEnumeration * U_EXPORT2
ucnv_openAllNames(UErrorCode *pErrorCode);

/**
* Gives the number of aliases for a given converter or alias name.
* If the alias is ambiguous, then the preferred converter is used
* and the status is set to U_AMBIGUOUS_ALIAS_WARNING.
* This method only enumerates the listed entries in the alias file.
* @param alias alias name
* @param pErrorCode error status
* @return number of names on alias list for given alias
* @stable ICU 2.0
*/
U_CAPI uint16_t U_EXPORT2
ucnv_countAliases(const char *alias, UErrorCode *pErrorCode);

/**
* Gives the name of the alias at given index of alias list.
* This method only enumerates the listed entries in the alias file.
* If the alias is ambiguous, then the preferred converter is used
* and the status is set to U_AMBIGUOUS_ALIAS_WARNING.
* @param alias alias name
* @param n index in alias list
* @param pErrorCode result of operation
* @return returns the name of the alias at given index
* @see ucnv_countAliases
* @stable ICU 2.0
*/
U_CAPI const char * U_EXPORT2
ucnv_getAlias(const char *alias, uint16_t n, UErrorCode *pErrorCode);

/**
* Fill-up the list of alias names for the given alias.
* This method only enumerates the listed entries in the alias file.
* If the alias is ambiguous, then the preferred converter is used
* and the status is set to U_AMBIGUOUS_ALIAS_WARNING.
* @param alias alias name
* @param aliases fill-in list, aliases is a pointer to an array of
*        <code>ucnv_countAliases()</code> string-pointers
*        (<code>const char *</code>) that will be filled in.
*        The strings themselves are owned by the library.
* @param pErrorCode result of operation
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ucnv_getAliases(const char *alias, const char **aliases, UErrorCode *pErrorCode);

/**
* Return a new UEnumeration object for enumerating all the
* alias names for a given converter that are recognized by a standard.
* This method only enumerates the listed entries in the alias file.
* The convrtrs.txt file can be modified to change the results of
* this function.
* The first result in this list is the same result given by
* <code>ucnv_getStandardName</code>, which is the default alias for
* the specified standard name. The returned object must be closed with
* <code>uenum_close</code> when you are done with the object.
*
* @param convName original converter name
* @param standard name of the standard governing the names; MIME and IANA
*      are such standards
* @param pErrorCode The error code
* @return A UEnumeration object for getting all aliases that are recognized
*      by a standard. If any of the parameters are invalid, NULL
*      is returned.
* @see ucnv_getStandardName
* @see uenum_close
* @see uenum_next
* @stable ICU 2.2
*/
U_CAPI UEnumeration * U_EXPORT2
ucnv_openStandardNames(const char *convName,
                      const char *standard,
                      UErrorCode *pErrorCode);

/**
* Gives the number of standards associated to converter names.
* @return number of standards
* @stable ICU 2.0
*/
U_CAPI uint16_t U_EXPORT2
ucnv_countStandards(void);

/**
* Gives the name of the standard at given index of standard list.
* @param n index in standard list
* @param pErrorCode result of operation
* @return returns the name of the standard at given index. Owned by the library.
* @stable ICU 2.0
*/
U_CAPI const char * U_EXPORT2
ucnv_getStandard(uint16_t n, UErrorCode *pErrorCode);

/**
* Returns a standard name for a given converter name.
* <p>
* Example alias table:<br>
* conv alias1 { STANDARD1 } alias2 { STANDARD1* }
* <p>
* Result of ucnv_getStandardName("conv", "STANDARD1") from example
* alias table:<br>
* <b>"alias2"</b>
*
* @param name original converter name
* @param standard name of the standard governing the names; MIME and IANA
*        are such standards
* @param pErrorCode result of operation
* @return returns the standard converter name;
*         if a standard converter name cannot be determined,
*         then <code>NULL</code> is returned. Owned by the library.
* @stable ICU 2.0
*/
U_CAPI const char * U_EXPORT2
ucnv_getStandardName(const char *name, const char *standard, UErrorCode *pErrorCode);

/**
* This function will return the internal canonical converter name of the
* tagged alias. This is the opposite of ucnv_openStandardNames, which
* returns the tagged alias given the canonical name.
* <p>
* Example alias table:<br>
* conv alias1 { STANDARD1 } alias2 { STANDARD1* }
* <p>
* Result of ucnv_getStandardName("alias1", "STANDARD1") from example
* alias table:<br>
* <b>"conv"</b>
*
* @return returns the canonical converter name;
*         if a standard or alias name cannot be determined,
*         then <code>NULL</code> is returned. The returned string is
*         owned by the library.
* @see ucnv_getStandardName
* @stable ICU 2.4
*/
U_CAPI const char * U_EXPORT2
ucnv_getCanonicalName(const char *alias, const char *standard, UErrorCode *pErrorCode);

/**
* Returns the current default converter name. If you want to open
* a default converter, you do not need to use this function.
* It is faster if you pass a NULL argument to ucnv_open the
* default converter.
*
* If U_CHARSET_IS_UTF8 is defined to 1 in utypes.h then this function
* always returns "UTF-8".
*
* @return returns the current default converter name.
*         Storage owned by the library
* @see ucnv_setDefaultName
* @stable ICU 2.0
*/
U_CAPI const char * U_EXPORT2
ucnv_getDefaultName(void);

#ifndef U_HIDE_SYSTEM_API
/**
* This function is not thread safe. DO NOT call this function when ANY ICU
* function is being used from more than one thread! This function sets the
* current default converter name. If this function needs to be called, it
* should be called during application initialization. Most of the time, the
* results from ucnv_getDefaultName() or ucnv_open with a NULL string argument
* is sufficient for your application.
*
* If U_CHARSET_IS_UTF8 is defined to 1 in utypes.h then this function
* does nothing.
*
* @param name the converter name to be the default (must be known by ICU).
* @see ucnv_getDefaultName
* @system
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ucnv_setDefaultName(const char *name);
#endif  /* U_HIDE_SYSTEM_API */

/**
* Fixes the backslash character mismapping.  For example, in SJIS, the backslash
* character in the ASCII portion is also used to represent the yen currency sign.
* When mapping from Unicode character 0x005C, it's unclear whether to map the
* character back to yen or backslash in SJIS.  This function will take the input
* buffer and replace all the yen sign characters with backslash.  This is necessary
* when the user tries to open a file with the input buffer on Windows.
* This function will test the converter to see whether such mapping is
* required.  You can sometimes avoid using this function by using the correct version
* of Shift-JIS.
*
* @param cnv The converter representing the target codepage.
* @param source the input buffer to be fixed
* @param sourceLen the length of the input buffer
* @see ucnv_isAmbiguous
* @stable ICU 2.0
*/
U_CAPI void U_EXPORT2
ucnv_fixFileSeparator(const UConverter *cnv, UChar *source, int32_t sourceLen);

/**
* Determines if the converter contains ambiguous mappings of the same
* character or not.
* @param cnv the converter to be tested
* @return true if the converter contains ambiguous mapping of the same
* character, false otherwise.
* @stable ICU 2.0
*/
U_CAPI UBool U_EXPORT2
ucnv_isAmbiguous(const UConverter *cnv);

/**
* Sets the converter to use fallback mappings or not.
* Regardless of this flag, the converter will always use
* fallbacks from Unicode Private Use code points, as well as
* reverse fallbacks (to Unicode).
* For details see ".ucm File Format"
* in the Conversion Data chapter of the ICU User Guide:
* https://unicode-org.github.io/icu/userguide/conversion/data.html#ucm-file-format
*
* @param cnv The converter to set the fallback mapping usage on.
* @param usesFallback true if the user wants the converter to take advantage of the fallback
* mapping, false otherwise.
* @stable ICU 2.0
* @see ucnv_usesFallback
*/
U_CAPI void U_EXPORT2
ucnv_setFallback(UConverter *cnv, UBool usesFallback);

/**
* Determines if the converter uses fallback mappings or not.
* This flag has restrictions, see ucnv_setFallback().
*
* @param cnv The converter to be tested
* @return true if the converter uses fallback, false otherwise.
* @stable ICU 2.0
* @see ucnv_setFallback
*/
U_CAPI UBool U_EXPORT2
ucnv_usesFallback(const UConverter *cnv);

/**
* Detects Unicode signature byte sequences at the start of the byte stream
* and returns the charset name of the indicated Unicode charset.
* NULL is returned when no Unicode signature is recognized.
* The number of bytes in the signature is output as well.
*
* The caller can ucnv_open() a converter using the charset name.
* The first code unit (UChar) from the start of the stream will be U+FEFF
* (the Unicode BOM/signature character) and can usually be ignored.
*
* For most Unicode charsets it is also possible to ignore the indicated
* number of initial stream bytes and start converting after them.
* However, there are stateful Unicode charsets (UTF-7 and BOCU-1) for which
* this will not work. Therefore, it is best to ignore the first output UChar
* instead of the input signature bytes.
* <p>
* Usage:
*
* @param source            The source string in which the signature should be detected.
* @param sourceLength      Length of the input string, or -1 if terminated with a NUL byte.
* @param signatureLength   A pointer to int32_t to receive the number of bytes that make up the signature
*                          of the detected UTF. 0 if not detected.
*                          Can be a NULL pointer.
* @param pErrorCode        ICU error code in/out parameter.
*                          Must fulfill U_SUCCESS before the function call.
* @return The name of the encoding detected. NULL if encoding is not detected.
* @stable ICU 2.4
*/
U_CAPI const char* U_EXPORT2
ucnv_detectUnicodeSignature(const char* source,
                           int32_t sourceLength,
                           int32_t *signatureLength,
                           UErrorCode *pErrorCode);

/**
* Returns the number of UChars held in the converter's internal state
* because more input is needed for completing the conversion. This function is
* useful for mapping semantics of ICU's converter interface to those of iconv,
* and this information is not needed for normal conversion.
* @param cnv       The converter in which the input is held
* @param status    ICU error code in/out parameter.
*                  Must fulfill U_SUCCESS before the function call.
* @return The number of UChars in the state. -1 if an error is encountered.
* @stable ICU 3.4
*/
U_CAPI int32_t U_EXPORT2
ucnv_fromUCountPending(const UConverter* cnv, UErrorCode* status);

/**
* Returns the number of chars held in the converter's internal state
* because more input is needed for completing the conversion. This function is
* useful for mapping semantics of ICU's converter interface to those of iconv,
* and this information is not needed for normal conversion.
* @param cnv       The converter in which the input is held as internal state
* @param status    ICU error code in/out parameter.
*                  Must fulfill U_SUCCESS before the function call.
* @return The number of chars in the state. -1 if an error is encountered.
* @stable ICU 3.4
*/
U_CAPI int32_t U_EXPORT2
ucnv_toUCountPending(const UConverter* cnv, UErrorCode* status);

/**
* Returns whether or not the charset of the converter has a fixed number of bytes
* per charset character.
* An example of this are converters that are of the type UCNV_SBCS or UCNV_DBCS.
* Another example is UTF-32 which is always 4 bytes per character.
* A Unicode code point may be represented by more than one UTF-8 or UTF-16 code unit
* but a UTF-32 converter encodes each code point with 4 bytes.
* Note: This method is not intended to be used to determine whether the charset has a
* fixed ratio of bytes to Unicode codes <i>units</i> for any particular Unicode encoding form.
* false is returned with the UErrorCode if error occurs or cnv is NULL.
* @param cnv       The converter to be tested
* @param status    ICU error code in/out parameter
* @return true if the converter is fixed-width
* @stable ICU 4.8
*/
U_CAPI UBool U_EXPORT2
ucnv_isFixedWidth(UConverter *cnv, UErrorCode *status);

#endif

#endif
/*_UCNV*/