utils.h (7152B)
1 // Copyright 2012 Google Inc. All Rights Reserved. 2 // 3 // Use of this source code is governed by a BSD-style license 4 // that can be found in the COPYING file in the root of the source 5 // tree. An additional intellectual property rights grant can be found 6 // in the file PATENTS. All contributing project authors may 7 // be found in the AUTHORS file in the root of the source tree. 8 // ----------------------------------------------------------------------------- 9 // 10 // Misc. common utility functions 11 // 12 // Authors: Skal (pascal.massimino@gmail.com) 13 // Urvang (urvang@google.com) 14 15 #ifndef WEBP_UTILS_UTILS_H_ 16 #define WEBP_UTILS_UTILS_H_ 17 18 #ifdef HAVE_CONFIG_H 19 #include "src/webp/config.h" 20 #endif 21 22 #include <assert.h> 23 24 #include "src/webp/types.h" 25 26 #ifdef __cplusplus 27 extern "C" { 28 #endif 29 30 //------------------------------------------------------------------------------ 31 // Memory allocation 32 33 // This is the maximum memory amount that libwebp will ever try to allocate. 34 #ifndef WEBP_MAX_ALLOCABLE_MEMORY 35 #if SIZE_MAX > (1ULL << 34) 36 #define WEBP_MAX_ALLOCABLE_MEMORY (1ULL << 34) 37 #else 38 // For 32-bit targets keep this below INT_MAX to avoid valgrind warnings. 39 #define WEBP_MAX_ALLOCABLE_MEMORY ((1ULL << 31) - (1 << 16)) 40 #endif 41 #endif // WEBP_MAX_ALLOCABLE_MEMORY 42 43 static WEBP_INLINE int CheckSizeOverflow(uint64_t size) { 44 return size == (size_t)size; 45 } 46 47 // size-checking safe malloc/calloc: verify that the requested size is not too 48 // large, or return NULL. You don't need to call these for constructs like 49 // malloc(sizeof(foo)), but only if there's picture-dependent size involved 50 // somewhere (like: malloc(num_pixels * sizeof(*something))). That's why this 51 // safe malloc() borrows the signature from calloc(), pointing at the dangerous 52 // underlying multiply involved. 53 WEBP_EXTERN void* WebPSafeMalloc(uint64_t nmemb, size_t size); 54 // Note that WebPSafeCalloc() expects the second argument type to be 'size_t' 55 // in order to favor the "calloc(num_foo, sizeof(foo))" pattern. 56 WEBP_EXTERN void* WebPSafeCalloc(uint64_t nmemb, size_t size); 57 58 // Companion deallocation function to the above allocations. 59 WEBP_EXTERN void WebPSafeFree(void* const ptr); 60 61 //------------------------------------------------------------------------------ 62 // Alignment 63 64 #define WEBP_ALIGN_CST 31 65 #define WEBP_ALIGN(PTR) (((uintptr_t)(PTR) + WEBP_ALIGN_CST) & \ 66 ~(uintptr_t)WEBP_ALIGN_CST) 67 68 #include <string.h> 69 // memcpy() is the safe way of moving potentially unaligned 32b memory. 70 static WEBP_INLINE uint32_t WebPMemToUint32(const uint8_t* const ptr) { 71 uint32_t A; 72 memcpy(&A, ptr, sizeof(A)); 73 return A; 74 } 75 76 static WEBP_INLINE int32_t WebPMemToInt32(const uint8_t* const ptr) { 77 return (int32_t)WebPMemToUint32(ptr); 78 } 79 80 static WEBP_INLINE void WebPUint32ToMem(uint8_t* const ptr, uint32_t val) { 81 memcpy(ptr, &val, sizeof(val)); 82 } 83 84 static WEBP_INLINE void WebPInt32ToMem(uint8_t* const ptr, int val) { 85 WebPUint32ToMem(ptr, (uint32_t)val); 86 } 87 88 //------------------------------------------------------------------------------ 89 // Reading/writing data. 90 91 // Read 16, 24 or 32 bits stored in little-endian order. 92 static WEBP_INLINE int GetLE16(const uint8_t* const data) { 93 return (int)(data[0] << 0) | (data[1] << 8); 94 } 95 96 static WEBP_INLINE int GetLE24(const uint8_t* const data) { 97 return GetLE16(data) | (data[2] << 16); 98 } 99 100 static WEBP_INLINE uint32_t GetLE32(const uint8_t* const data) { 101 return GetLE16(data) | ((uint32_t)GetLE16(data + 2) << 16); 102 } 103 104 // Store 16, 24 or 32 bits in little-endian order. 105 static WEBP_INLINE void PutLE16(uint8_t* const data, int val) { 106 assert(val < (1 << 16)); 107 data[0] = (val >> 0) & 0xff; 108 data[1] = (val >> 8) & 0xff; 109 } 110 111 static WEBP_INLINE void PutLE24(uint8_t* const data, int val) { 112 assert(val < (1 << 24)); 113 PutLE16(data, val & 0xffff); 114 data[2] = (val >> 16) & 0xff; 115 } 116 117 static WEBP_INLINE void PutLE32(uint8_t* const data, uint32_t val) { 118 PutLE16(data, (int)(val & 0xffff)); 119 PutLE16(data + 2, (int)(val >> 16)); 120 } 121 122 // use GNU builtins where available. 123 #if defined(__GNUC__) && \ 124 ((__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || __GNUC__ >= 4) 125 // Returns (int)floor(log2(n)). n must be > 0. 126 static WEBP_INLINE int BitsLog2Floor(uint32_t n) { 127 return 31 ^ __builtin_clz(n); 128 } 129 // counts the number of trailing zero 130 static WEBP_INLINE int BitsCtz(uint32_t n) { return __builtin_ctz(n); } 131 #elif defined(_MSC_VER) && _MSC_VER > 1310 && \ 132 (defined(_M_X64) || defined(_M_IX86)) 133 #include <intrin.h> 134 #pragma intrinsic(_BitScanReverse) 135 #pragma intrinsic(_BitScanForward) 136 137 static WEBP_INLINE int BitsLog2Floor(uint32_t n) { 138 unsigned long first_set_bit; // NOLINT (runtime/int) 139 _BitScanReverse(&first_set_bit, n); 140 return first_set_bit; 141 } 142 static WEBP_INLINE int BitsCtz(uint32_t n) { 143 unsigned long first_set_bit; // NOLINT (runtime/int) 144 _BitScanForward(&first_set_bit, n); 145 return first_set_bit; 146 } 147 #else // default: use the (slow) C-version. 148 #define WEBP_HAVE_SLOW_CLZ_CTZ // signal that the Clz/Ctz function are slow 149 // Returns 31 ^ clz(n) = log2(n). This is the default C-implementation, either 150 // based on table or not. Can be used as fallback if clz() is not available. 151 #define WEBP_NEED_LOG_TABLE_8BIT 152 extern const uint8_t WebPLogTable8bit[256]; 153 static WEBP_INLINE int WebPLog2FloorC(uint32_t n) { 154 int log_value = 0; 155 while (n >= 256) { 156 log_value += 8; 157 n >>= 8; 158 } 159 return log_value + WebPLogTable8bit[n]; 160 } 161 162 static WEBP_INLINE int BitsLog2Floor(uint32_t n) { return WebPLog2FloorC(n); } 163 164 static WEBP_INLINE int BitsCtz(uint32_t n) { 165 int i; 166 for (i = 0; i < 32; ++i, n >>= 1) { 167 if (n & 1) return i; 168 } 169 return 32; 170 } 171 172 #endif 173 174 //------------------------------------------------------------------------------ 175 // Pixel copying. 176 177 struct WebPPicture; 178 179 // Copy width x height pixels from 'src' to 'dst' honoring the strides. 180 WEBP_EXTERN void WebPCopyPlane(const uint8_t* src, int src_stride, 181 uint8_t* dst, int dst_stride, 182 int width, int height); 183 184 // Copy ARGB pixels from 'src' to 'dst' honoring strides. 'src' and 'dst' are 185 // assumed to be already allocated and using ARGB data. 186 WEBP_EXTERN void WebPCopyPixels(const struct WebPPicture* const src, 187 struct WebPPicture* const dst); 188 189 //------------------------------------------------------------------------------ 190 // Unique colors. 191 192 // Returns count of unique colors in 'pic', assuming pic->use_argb is true. 193 // If the unique color count is more than MAX_PALETTE_SIZE, returns 194 // MAX_PALETTE_SIZE+1. 195 // If 'palette' is not NULL and number of unique colors is less than or equal to 196 // MAX_PALETTE_SIZE, also outputs the actual unique colors into 'palette'. 197 // Note: 'palette' is assumed to be an array already allocated with at least 198 // MAX_PALETTE_SIZE elements. 199 // TODO(vrabaud) remove whenever we can break the ABI. 200 WEBP_EXTERN int WebPGetColorPalette(const struct WebPPicture* const pic, 201 uint32_t* const palette); 202 203 //------------------------------------------------------------------------------ 204 205 #ifdef __cplusplus 206 } // extern "C" 207 #endif 208 209 #endif // WEBP_UTILS_UTILS_H_