jcmainct.c (5632B)
1 /* 2 * jcmainct.c 3 * 4 * This file was part of the Independent JPEG Group's software: 5 * Copyright (C) 1994-1996, Thomas G. Lane. 6 * Lossless JPEG Modifications: 7 * Copyright (C) 1999, Ken Murchison. 8 * libjpeg-turbo Modifications: 9 * Copyright (C) 2022, D. R. Commander. 10 * For conditions of distribution and use, see the accompanying README.ijg 11 * file. 12 * 13 * This file contains the main buffer controller for compression. 14 * The main buffer lies between the pre-processor and the JPEG 15 * compressor proper; it holds downsampled data in the JPEG colorspace. 16 */ 17 18 #define JPEG_INTERNALS 19 #include "jinclude.h" 20 #include "jpeglib.h" 21 #include "jsamplecomp.h" 22 23 24 #if BITS_IN_JSAMPLE != 16 || defined(C_LOSSLESS_SUPPORTED) 25 26 /* Private buffer controller object */ 27 28 typedef struct { 29 struct jpeg_c_main_controller pub; /* public fields */ 30 31 JDIMENSION cur_iMCU_row; /* number of current iMCU row */ 32 JDIMENSION rowgroup_ctr; /* counts row groups received in iMCU row */ 33 boolean suspended; /* remember if we suspended output */ 34 J_BUF_MODE pass_mode; /* current operating mode */ 35 36 /* If using just a strip buffer, this points to the entire set of buffers 37 * (we allocate one for each component). In the full-image case, this 38 * points to the currently accessible strips of the virtual arrays. 39 */ 40 _JSAMPARRAY buffer[MAX_COMPONENTS]; 41 } my_main_controller; 42 43 typedef my_main_controller *my_main_ptr; 44 45 46 /* Forward declarations */ 47 METHODDEF(void) process_data_simple_main(j_compress_ptr cinfo, 48 _JSAMPARRAY input_buf, 49 JDIMENSION *in_row_ctr, 50 JDIMENSION in_rows_avail); 51 52 53 /* 54 * Initialize for a processing pass. 55 */ 56 57 METHODDEF(void) 58 start_pass_main(j_compress_ptr cinfo, J_BUF_MODE pass_mode) 59 { 60 my_main_ptr main_ptr = (my_main_ptr)cinfo->main; 61 62 /* Do nothing in raw-data mode. */ 63 if (cinfo->raw_data_in) 64 return; 65 66 if (pass_mode != JBUF_PASS_THRU) 67 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); 68 69 main_ptr->cur_iMCU_row = 0; /* initialize counters */ 70 main_ptr->rowgroup_ctr = 0; 71 main_ptr->suspended = FALSE; 72 main_ptr->pass_mode = pass_mode; /* save mode for use by process_data */ 73 main_ptr->pub._process_data = process_data_simple_main; 74 } 75 76 77 /* 78 * Process some data. 79 * This routine handles the simple pass-through mode, 80 * where we have only a strip buffer. 81 */ 82 83 METHODDEF(void) 84 process_data_simple_main(j_compress_ptr cinfo, _JSAMPARRAY input_buf, 85 JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail) 86 { 87 my_main_ptr main_ptr = (my_main_ptr)cinfo->main; 88 JDIMENSION data_unit = cinfo->master->lossless ? 1 : DCTSIZE; 89 90 while (main_ptr->cur_iMCU_row < cinfo->total_iMCU_rows) { 91 /* Read input data if we haven't filled the main buffer yet */ 92 if (main_ptr->rowgroup_ctr < data_unit) 93 (*cinfo->prep->_pre_process_data) (cinfo, input_buf, in_row_ctr, 94 in_rows_avail, main_ptr->buffer, 95 &main_ptr->rowgroup_ctr, data_unit); 96 97 /* If we don't have a full iMCU row buffered, return to application for 98 * more data. Note that preprocessor will always pad to fill the iMCU row 99 * at the bottom of the image. 100 */ 101 if (main_ptr->rowgroup_ctr != data_unit) 102 return; 103 104 /* Send the completed row to the compressor */ 105 if (!(*cinfo->coef->_compress_data) (cinfo, main_ptr->buffer)) { 106 /* If compressor did not consume the whole row, then we must need to 107 * suspend processing and return to the application. In this situation 108 * we pretend we didn't yet consume the last input row; otherwise, if 109 * it happened to be the last row of the image, the application would 110 * think we were done. 111 */ 112 if (!main_ptr->suspended) { 113 (*in_row_ctr)--; 114 main_ptr->suspended = TRUE; 115 } 116 return; 117 } 118 /* We did finish the row. Undo our little suspension hack if a previous 119 * call suspended; then mark the main buffer empty. 120 */ 121 if (main_ptr->suspended) { 122 (*in_row_ctr)++; 123 main_ptr->suspended = FALSE; 124 } 125 main_ptr->rowgroup_ctr = 0; 126 main_ptr->cur_iMCU_row++; 127 } 128 } 129 130 131 /* 132 * Initialize main buffer controller. 133 */ 134 135 GLOBAL(void) 136 _jinit_c_main_controller(j_compress_ptr cinfo, boolean need_full_buffer) 137 { 138 my_main_ptr main_ptr; 139 int ci; 140 jpeg_component_info *compptr; 141 int data_unit = cinfo->master->lossless ? 1 : DCTSIZE; 142 143 if (cinfo->data_precision != BITS_IN_JSAMPLE) 144 ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision); 145 146 main_ptr = (my_main_ptr) 147 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE, 148 sizeof(my_main_controller)); 149 cinfo->main = (struct jpeg_c_main_controller *)main_ptr; 150 main_ptr->pub.start_pass = start_pass_main; 151 152 /* We don't need to create a buffer in raw-data mode. */ 153 if (cinfo->raw_data_in) 154 return; 155 156 /* Create the buffer. It holds downsampled data, so each component 157 * may be of a different size. 158 */ 159 if (need_full_buffer) { 160 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); 161 } else { 162 /* Allocate a strip buffer for each component */ 163 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 164 ci++, compptr++) { 165 main_ptr->buffer[ci] = (_JSAMPARRAY)(*cinfo->mem->alloc_sarray) 166 ((j_common_ptr)cinfo, JPOOL_IMAGE, 167 compptr->width_in_blocks * data_unit, 168 (JDIMENSION)(compptr->v_samp_factor * data_unit)); 169 } 170 } 171 } 172 173 #endif /* BITS_IN_JSAMPLE != 16 || defined(C_LOSSLESS_SUPPORTED) */