1 /* 2 * jcmainct.c 3 * 4 * Copyright (C) 1994-1996, Thomas G. Lane. 5 * This file is part of the Independent JPEG Group's software. 6 * For conditions of distribution and use, see the accompanying README file. 7 * 8 * This file contains the main buffer controller for compression. 9 * The main buffer lies between the pre-processor and the JPEG 10 * compressor proper; it holds downsampled data in the JPEG colorspace. 11 */ 12 13 #define JPEG_INTERNALS 14 #include "jinclude.h" 15 #include "jpeglib.h" 16 17 18 /* Note: currently, there is no operating mode in which a full-image buffer 19 * is needed at this step. If there were, that mode could not be used with 20 * "raw data" input, since this module is bypassed in that case. However, 21 * we've left the code here for possible use in special applications. 22 */ 23 #undef FULL_MAIN_BUFFER_SUPPORTED 24 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 42 #ifdef FULL_MAIN_BUFFER_SUPPORTED 43 /* If using full-image storage, this array holds pointers to virtual-array 44 * control blocks for each component. Unused if not full-image storage. 45 */ 46 jvirt_sarray_ptr whole_image[MAX_COMPONENTS]; 47 #endif 48 } my_main_controller; 49 50 typedef my_main_controller * my_main_ptr; 51 52 53 /* Forward declarations */ 54 METHODDEF(void) process_data_simple_main 55 JPP((j_compress_ptr cinfo, JSAMPARRAY input_buf, 56 JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail)); 57 #ifdef FULL_MAIN_BUFFER_SUPPORTED 58 METHODDEF(void) process_data_buffer_main 59 JPP((j_compress_ptr cinfo, JSAMPARRAY input_buf, 60 JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail)); 61 #endif 62 63 64 /* 65 * Initialize for a processing pass. 66 */ 67 68 METHODDEF(void) 69 start_pass_main (j_compress_ptr cinfo, J_BUF_MODE pass_mode) 70 { 71 my_main_ptr main = (my_main_ptr) cinfo->main; 72 73 /* Do nothing in raw-data mode. */ 74 if (cinfo->raw_data_in) 75 return; 76 77 main->cur_iMCU_row = 0; /* initialize counters */ 78 main->rowgroup_ctr = 0; 79 main->suspended = FALSE; 80 main->pass_mode = pass_mode; /* save mode for use by process_data */ 81 82 switch (pass_mode) { 83 case JBUF_PASS_THRU: 84 #ifdef FULL_MAIN_BUFFER_SUPPORTED 85 if (main->whole_image[0] != NULL) 86 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); 87 #endif 88 main->pub.process_data = process_data_simple_main; 89 break; 90 #ifdef FULL_MAIN_BUFFER_SUPPORTED 91 case JBUF_SAVE_SOURCE: 92 case JBUF_CRANK_DEST: 93 case JBUF_SAVE_AND_PASS: 94 if (main->whole_image[0] == NULL) 95 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); 96 main->pub.process_data = process_data_buffer_main; 97 break; 98 #endif 99 default: 100 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); 101 break; 102 } 103 } 104 105 106 /* 107 * Process some data. 108 * This routine handles the simple pass-through mode, 109 * where we have only a strip buffer. 110 */ 111 112 METHODDEF(void) 113 process_data_simple_main (j_compress_ptr cinfo, 114 JSAMPARRAY input_buf, JDIMENSION *in_row_ctr, 115 JDIMENSION in_rows_avail) 116 { 117 my_main_ptr main = (my_main_ptr) cinfo->main; 118 119 while (main->cur_iMCU_row < cinfo->total_iMCU_rows) { 120 /* Read input data if we haven't filled the main buffer yet */ 121 if (main->rowgroup_ctr < DCTSIZE) 122 (*cinfo->prep->pre_process_data) (cinfo, 123 input_buf, in_row_ctr, in_rows_avail, 124 main->buffer, &main->rowgroup_ctr, 125 (JDIMENSION) DCTSIZE); 126 127 /* If we don't have a full iMCU row buffered, return to application for 128 * more data. Note that preprocessor will always pad to fill the iMCU row 129 * at the bottom of the image. 130 */ 131 if (main->rowgroup_ctr != DCTSIZE) 132 return; 133 134 /* Send the completed row to the compressor */ 135 if (! (*cinfo->coef->compress_data) (cinfo, main->buffer)) { 136 /* If compressor did not consume the whole row, then we must need to 137 * suspend processing and return to the application. In this situation 138 * we pretend we didn't yet consume the last input row; otherwise, if 139 * it happened to be the last row of the image, the application would 140 * think we were done. 141 */ 142 if (! main->suspended) { 143 (*in_row_ctr)--; 144 main->suspended = TRUE; 145 } 146 return; 147 } 148 /* We did finish the row. Undo our little suspension hack if a previous 149 * call suspended; then mark the main buffer empty. 150 */ 151 if (main->suspended) { 152 (*in_row_ctr)++; 153 main->suspended = FALSE; 154 } 155 main->rowgroup_ctr = 0; 156 main->cur_iMCU_row++; 157 } 158 } 159 160 161 #ifdef FULL_MAIN_BUFFER_SUPPORTED 162 163 /* 164 * Process some data. 165 * This routine handles all of the modes that use a full-size buffer. 166 */ 167 168 METHODDEF(void) 169 process_data_buffer_main (j_compress_ptr cinfo, 170 JSAMPARRAY input_buf, JDIMENSION *in_row_ctr, 171 JDIMENSION in_rows_avail) 172 { 173 my_main_ptr main = (my_main_ptr) cinfo->main; 174 int ci; 175 jpeg_component_info *compptr; 176 boolean writing = (main->pass_mode != JBUF_CRANK_DEST); 177 178 while (main->cur_iMCU_row < cinfo->total_iMCU_rows) { 179 /* Realign the virtual buffers if at the start of an iMCU row. */ 180 if (main->rowgroup_ctr == 0) { 181 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 182 ci++, compptr++) { 183 main->buffer[ci] = (*cinfo->mem->access_virt_sarray) 184 ((j_common_ptr) cinfo, main->whole_image[ci], 185 main->cur_iMCU_row * (compptr->v_samp_factor * DCTSIZE), 186 (JDIMENSION) (compptr->v_samp_factor * DCTSIZE), writing); 187 } 188 /* In a read pass, pretend we just read some source data. */ 189 if (! writing) { 190 *in_row_ctr += cinfo->max_v_samp_factor * DCTSIZE; 191 main->rowgroup_ctr = DCTSIZE; 192 } 193 } 194 195 /* If a write pass, read input data until the current iMCU row is full. */ 196 /* Note: preprocessor will pad if necessary to fill the last iMCU row. */ 197 if (writing) { 198 (*cinfo->prep->pre_process_data) (cinfo, 199 input_buf, in_row_ctr, in_rows_avail, 200 main->buffer, &main->rowgroup_ctr, 201 (JDIMENSION) DCTSIZE); 202 /* Return to application if we need more data to fill the iMCU row. */ 203 if (main->rowgroup_ctr < DCTSIZE) 204 return; 205 } 206 207 /* Emit data, unless this is a sink-only pass. */ 208 if (main->pass_mode != JBUF_SAVE_SOURCE) { 209 if (! (*cinfo->coef->compress_data) (cinfo, main->buffer)) { 210 /* If compressor did not consume the whole row, then we must need to 211 * suspend processing and return to the application. In this situation 212 * we pretend we didn't yet consume the last input row; otherwise, if 213 * it happened to be the last row of the image, the application would 214 * think we were done. 215 */ 216 if (! main->suspended) { 217 (*in_row_ctr)--; 218 main->suspended = TRUE; 219 } 220 return; 221 } 222 /* We did finish the row. Undo our little suspension hack if a previous 223 * call suspended; then mark the main buffer empty. 224 */ 225 if (main->suspended) { 226 (*in_row_ctr)++; 227 main->suspended = FALSE; 228 } 229 } 230 231 /* If get here, we are done with this iMCU row. Mark buffer empty. */ 232 main->rowgroup_ctr = 0; 233 main->cur_iMCU_row++; 234 } 235 } 236 237 #endif /* FULL_MAIN_BUFFER_SUPPORTED */ 238 239 240 /* 241 * Initialize main buffer controller. 242 */ 243 244 GLOBAL(void) 245 jinit_c_main_controller (j_compress_ptr cinfo, boolean need_full_buffer) 246 { 247 my_main_ptr main; 248 int ci; 249 jpeg_component_info *compptr; 250 251 main = (my_main_ptr) 252 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 253 SIZEOF(my_main_controller)); 254 cinfo->main = (struct jpeg_c_main_controller *) main; 255 main->pub.start_pass = start_pass_main; 256 257 /* We don't need to create a buffer in raw-data mode. */ 258 if (cinfo->raw_data_in) 259 return; 260 261 /* Create the buffer. It holds downsampled data, so each component 262 * may be of a different size. 263 */ 264 if (need_full_buffer) { 265 #ifdef FULL_MAIN_BUFFER_SUPPORTED 266 /* Allocate a full-image virtual array for each component */ 267 /* Note we pad the bottom to a multiple of the iMCU height */ 268 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 269 ci++, compptr++) { 270 main->whole_image[ci] = (*cinfo->mem->request_virt_sarray) 271 ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE, 272 compptr->width_in_blocks * DCTSIZE, 273 (JDIMENSION) jround_up((long) compptr->height_in_blocks, 274 (long) compptr->v_samp_factor) * DCTSIZE, 275 (JDIMENSION) (compptr->v_samp_factor * DCTSIZE)); 276 } 277 #else 278 ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); 279 #endif 280 } else { 281 #ifdef FULL_MAIN_BUFFER_SUPPORTED 282 main->whole_image[0] = NULL; /* flag for no virtual arrays */ 283 #endif 284 /* Allocate a strip buffer for each component */ 285 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 286 ci++, compptr++) { 287 main->buffer[ci] = (*cinfo->mem->alloc_sarray) 288 ((j_common_ptr) cinfo, JPOOL_IMAGE, 289 compptr->width_in_blocks * DCTSIZE, 290 (JDIMENSION) (compptr->v_samp_factor * DCTSIZE)); 291 } 292 } 293 } 294
