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Diffstat (limited to 'jpg/jdmainct.c')
| -rw-r--r-- | jpg/jdmainct.c | 512 |
1 files changed, 0 insertions, 512 deletions
diff --git a/jpg/jdmainct.c b/jpg/jdmainct.c deleted file mode 100644 index 02723ca..0000000 --- a/jpg/jdmainct.c +++ /dev/null @@ -1,512 +0,0 @@ -/* - * jdmainct.c - * - * Copyright (C) 1994-1996, Thomas G. Lane. - * This file is part of the Independent JPEG Group's software. - * For conditions of distribution and use, see the accompanying README file. - * - * This file contains the main buffer controller for decompression. - * The main buffer lies between the JPEG decompressor proper and the - * post-processor; it holds downsampled data in the JPEG colorspace. - * - * Note that this code is bypassed in raw-data mode, since the application - * supplies the equivalent of the main buffer in that case. - */ - -#define JPEG_INTERNALS -#include "jinclude.h" -#include "jpeglib.h" - - -/* - * In the current system design, the main buffer need never be a full-image - * buffer; any full-height buffers will be found inside the coefficient or - * postprocessing controllers. Nonetheless, the main controller is not - * trivial. Its responsibility is to provide context rows for upsampling/ - * rescaling, and doing this in an efficient fashion is a bit tricky. - * - * Postprocessor input data is counted in "row groups". A row group - * is defined to be (v_samp_factor * DCT_scaled_size / min_DCT_scaled_size) - * sample rows of each component. (We require DCT_scaled_size values to be - * chosen such that these numbers are integers. In practice DCT_scaled_size - * values will likely be powers of two, so we actually have the stronger - * condition that DCT_scaled_size / min_DCT_scaled_size is an integer.) - * Upsampling will typically produce max_v_samp_factor pixel rows from each - * row group (times any additional scale factor that the upsampler is - * applying). - * - * The coefficient controller will deliver data to us one iMCU row at a time; - * each iMCU row contains v_samp_factor * DCT_scaled_size sample rows, or - * exactly min_DCT_scaled_size row groups. (This amount of data corresponds - * to one row of MCUs when the image is fully interleaved.) Note that the - * number of sample rows varies across components, but the number of row - * groups does not. Some garbage sample rows may be included in the last iMCU - * row at the bottom of the image. - * - * Depending on the vertical scaling algorithm used, the upsampler may need - * access to the sample row(s) above and below its current input row group. - * The upsampler is required to set need_context_rows TRUE at global selection - * time if so. When need_context_rows is FALSE, this controller can simply - * obtain one iMCU row at a time from the coefficient controller and dole it - * out as row groups to the postprocessor. - * - * When need_context_rows is TRUE, this controller guarantees that the buffer - * passed to postprocessing contains at least one row group's worth of samples - * above and below the row group(s) being processed. Note that the context - * rows "above" the first passed row group appear at negative row offsets in - * the passed buffer. At the top and bottom of the image, the required - * context rows are manufactured by duplicating the first or last real sample - * row; this avoids having special cases in the upsampling inner loops. - * - * The amount of context is fixed at one row group just because that's a - * convenient number for this controller to work with. The existing - * upsamplers really only need one sample row of context. An upsampler - * supporting arbitrary output rescaling might wish for more than one row - * group of context when shrinking the image; tough, we don't handle that. - * (This is justified by the assumption that downsizing will be handled mostly - * by adjusting the DCT_scaled_size values, so that the actual scale factor at - * the upsample step needn't be much less than one.) - * - * To provide the desired context, we have to retain the last two row groups - * of one iMCU row while reading in the next iMCU row. (The last row group - * can't be processed until we have another row group for its below-context, - * and so we have to save the next-to-last group too for its above-context.) - * We could do this most simply by copying data around in our buffer, but - * that'd be very slow. We can avoid copying any data by creating a rather - * strange pointer structure. Here's how it works. We allocate a workspace - * consisting of M+2 row groups (where M = min_DCT_scaled_size is the number - * of row groups per iMCU row). We create two sets of redundant pointers to - * the workspace. Labeling the physical row groups 0 to M+1, the synthesized - * pointer lists look like this: - * M+1 M-1 - * master pointer --> 0 master pointer --> 0 - * 1 1 - * ... ... - * M-3 M-3 - * M-2 M - * M-1 M+1 - * M M-2 - * M+1 M-1 - * 0 0 - * We read alternate iMCU rows using each master pointer; thus the last two - * row groups of the previous iMCU row remain un-overwritten in the workspace. - * The pointer lists are set up so that the required context rows appear to - * be adjacent to the proper places when we pass the pointer lists to the - * upsampler. - * - * The above pictures describe the normal state of the pointer lists. - * At top and bottom of the image, we diddle the pointer lists to duplicate - * the first or last sample row as necessary (this is cheaper than copying - * sample rows around). - * - * This scheme breaks down if M < 2, ie, min_DCT_scaled_size is 1. In that - * situation each iMCU row provides only one row group so the buffering logic - * must be different (eg, we must read two iMCU rows before we can emit the - * first row group). For now, we simply do not support providing context - * rows when min_DCT_scaled_size is 1. That combination seems unlikely to - * be worth providing --- if someone wants a 1/8th-size preview, they probably - * want it quick and dirty, so a context-free upsampler is sufficient. - */ - - -/* Private buffer controller object */ - -typedef struct { - struct jpeg_d_main_controller pub; /* public fields */ - - /* Pointer to allocated workspace (M or M+2 row groups). */ - JSAMPARRAY buffer[MAX_COMPONENTS]; - - boolean buffer_full; /* Have we gotten an iMCU row from decoder? */ - JDIMENSION rowgroup_ctr; /* counts row groups output to postprocessor */ - - /* Remaining fields are only used in the context case. */ - - /* These are the master pointers to the funny-order pointer lists. */ - JSAMPIMAGE xbuffer[2]; /* pointers to weird pointer lists */ - - int whichptr; /* indicates which pointer set is now in use */ - int context_state; /* process_data state machine status */ - JDIMENSION rowgroups_avail; /* row groups available to postprocessor */ - JDIMENSION iMCU_row_ctr; /* counts iMCU rows to detect image top/bot */ -} my_main_controller; - -typedef my_main_controller * my_main_ptr; - -/* context_state values: */ -#define CTX_PREPARE_FOR_IMCU 0 /* need to prepare for MCU row */ -#define CTX_PROCESS_IMCU 1 /* feeding iMCU to postprocessor */ -#define CTX_POSTPONED_ROW 2 /* feeding postponed row group */ - - -/* Forward declarations */ -METHODDEF(void) process_data_simple_main - JPP((j_decompress_ptr cinfo, JSAMPARRAY output_buf, - JDIMENSION *out_row_ctr, JDIMENSION out_rows_avail)); -METHODDEF(void) process_data_context_main - JPP((j_decompress_ptr cinfo, JSAMPARRAY output_buf, - JDIMENSION *out_row_ctr, JDIMENSION out_rows_avail)); -#ifdef QUANT_2PASS_SUPPORTED -METHODDEF(void) process_data_crank_post - JPP((j_decompress_ptr cinfo, JSAMPARRAY output_buf, - JDIMENSION *out_row_ctr, JDIMENSION out_rows_avail)); -#endif - - -LOCAL(void) -alloc_funny_pointers (j_decompress_ptr cinfo) -/* Allocate space for the funny pointer lists. - * This is done only once, not once per pass. - */ -{ - my_main_ptr main = (my_main_ptr) cinfo->main; - int ci, rgroup; - int M = cinfo->min_DCT_v_scaled_size; - jpeg_component_info *compptr; - JSAMPARRAY xbuf; - - /* Get top-level space for component array pointers. - * We alloc both arrays with one call to save a few cycles. - */ - main->xbuffer[0] = (JSAMPIMAGE) - (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, - cinfo->num_components * 2 * SIZEOF(JSAMPARRAY)); - main->xbuffer[1] = main->xbuffer[0] + cinfo->num_components; - - for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; - ci++, compptr++) { - rgroup = (compptr->v_samp_factor * compptr->DCT_v_scaled_size) / - cinfo->min_DCT_v_scaled_size; /* height of a row group of component */ - /* Get space for pointer lists --- M+4 row groups in each list. - * We alloc both pointer lists with one call to save a few cycles. - */ - xbuf = (JSAMPARRAY) - (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, - 2 * (rgroup * (M + 4)) * SIZEOF(JSAMPROW)); - xbuf += rgroup; /* want one row group at negative offsets */ - main->xbuffer[0][ci] = xbuf; - xbuf += rgroup * (M + 4); - main->xbuffer[1][ci] = xbuf; - } -} - - -LOCAL(void) -make_funny_pointers (j_decompress_ptr cinfo) -/* Create the funny pointer lists discussed in the comments above. - * The actual workspace is already allocated (in main->buffer), - * and the space for the pointer lists is allocated too. - * This routine just fills in the curiously ordered lists. - * This will be repeated at the beginning of each pass. - */ -{ - my_main_ptr main = (my_main_ptr) cinfo->main; - int ci, i, rgroup; - int M = cinfo->min_DCT_v_scaled_size; - jpeg_component_info *compptr; - JSAMPARRAY buf, xbuf0, xbuf1; - - for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; - ci++, compptr++) { - rgroup = (compptr->v_samp_factor * compptr->DCT_v_scaled_size) / - cinfo->min_DCT_v_scaled_size; /* height of a row group of component */ - xbuf0 = main->xbuffer[0][ci]; - xbuf1 = main->xbuffer[1][ci]; - /* First copy the workspace pointers as-is */ - buf = main->buffer[ci]; - for (i = 0; i < rgroup * (M + 2); i++) { - xbuf0[i] = xbuf1[i] = buf[i]; - } - /* In the second list, put the last four row groups in swapped order */ - for (i = 0; i < rgroup * 2; i++) { - xbuf1[rgroup*(M-2) + i] = buf[rgroup*M + i]; - xbuf1[rgroup*M + i] = buf[rgroup*(M-2) + i]; - } - /* The wraparound pointers at top and bottom will be filled later - * (see set_wraparound_pointers, below). Initially we want the "above" - * pointers to duplicate the first actual data line. This only needs - * to happen in xbuffer[0]. - */ - for (i = 0; i < rgroup; i++) { - xbuf0[i - rgroup] = xbuf0[0]; - } - } -} - - -LOCAL(void) -set_wraparound_pointers (j_decompress_ptr cinfo) -/* Set up the "wraparound" pointers at top and bottom of the pointer lists. - * This changes the pointer list state from top-of-image to the normal state. - */ -{ - my_main_ptr main = (my_main_ptr) cinfo->main; - int ci, i, rgroup; - int M = cinfo->min_DCT_v_scaled_size; - jpeg_component_info *compptr; - JSAMPARRAY xbuf0, xbuf1; - - for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; - ci++, compptr++) { - rgroup = (compptr->v_samp_factor * compptr->DCT_v_scaled_size) / - cinfo->min_DCT_v_scaled_size; /* height of a row group of component */ - xbuf0 = main->xbuffer[0][ci]; - xbuf1 = main->xbuffer[1][ci]; - for (i = 0; i < rgroup; i++) { - xbuf0[i - rgroup] = xbuf0[rgroup*(M+1) + i]; - xbuf1[i - rgroup] = xbuf1[rgroup*(M+1) + i]; - xbuf0[rgroup*(M+2) + i] = xbuf0[i]; - xbuf1[rgroup*(M+2) + i] = xbuf1[i]; - } - } -} - - -LOCAL(void) -set_bottom_pointers (j_decompress_ptr cinfo) -/* Change the pointer lists to duplicate the last sample row at the bottom - * of the image. whichptr indicates which xbuffer holds the final iMCU row. - * Also sets rowgroups_avail to indicate number of nondummy row groups in row. - */ -{ - my_main_ptr main = (my_main_ptr) cinfo->main; - int ci, i, rgroup, iMCUheight, rows_left; - jpeg_component_info *compptr; - JSAMPARRAY xbuf; - - for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; - ci++, compptr++) { - /* Count sample rows in one iMCU row and in one row group */ - iMCUheight = compptr->v_samp_factor * compptr->DCT_v_scaled_size; - rgroup = iMCUheight / cinfo->min_DCT_v_scaled_size; - /* Count nondummy sample rows remaining for this component */ - rows_left = (int) (compptr->downsampled_height % (JDIMENSION) iMCUheight); - if (rows_left == 0) rows_left = iMCUheight; - /* Count nondummy row groups. Should get same answer for each component, - * so we need only do it once. - */ - if (ci == 0) { - main->rowgroups_avail = (JDIMENSION) ((rows_left-1) / rgroup + 1); - } - /* Duplicate the last real sample row rgroup*2 times; this pads out the - * last partial rowgroup and ensures at least one full rowgroup of context. - */ - xbuf = main->xbuffer[main->whichptr][ci]; - for (i = 0; i < rgroup * 2; i++) { - xbuf[rows_left + i] = xbuf[rows_left-1]; - } - } -} - - -/* - * Initialize for a processing pass. - */ - -METHODDEF(void) -start_pass_main (j_decompress_ptr cinfo, J_BUF_MODE pass_mode) -{ - my_main_ptr main = (my_main_ptr) cinfo->main; - - switch (pass_mode) { - case JBUF_PASS_THRU: - if (cinfo->upsample->need_context_rows) { - main->pub.process_data = process_data_context_main; - make_funny_pointers(cinfo); /* Create the xbuffer[] lists */ - main->whichptr = 0; /* Read first iMCU row into xbuffer[0] */ - main->context_state = CTX_PREPARE_FOR_IMCU; - main->iMCU_row_ctr = 0; - } else { - /* Simple case with no context needed */ - main->pub.process_data = process_data_simple_main; - } - main->buffer_full = FALSE; /* Mark buffer empty */ - main->rowgroup_ctr = 0; - break; -#ifdef QUANT_2PASS_SUPPORTED - case JBUF_CRANK_DEST: - /* For last pass of 2-pass quantization, just crank the postprocessor */ - main->pub.process_data = process_data_crank_post; - break; -#endif - default: - ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); - break; - } -} - - -/* - * Process some data. - * This handles the simple case where no context is required. - */ - -METHODDEF(void) -process_data_simple_main (j_decompress_ptr cinfo, - JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, - JDIMENSION out_rows_avail) -{ - my_main_ptr main = (my_main_ptr) cinfo->main; - JDIMENSION rowgroups_avail; - - /* Read input data if we haven't filled the main buffer yet */ - if (! main->buffer_full) { - if (! (*cinfo->coef->decompress_data) (cinfo, main->buffer)) - return; /* suspension forced, can do nothing more */ - main->buffer_full = TRUE; /* OK, we have an iMCU row to work with */ - } - - /* There are always min_DCT_scaled_size row groups in an iMCU row. */ - rowgroups_avail = (JDIMENSION) cinfo->min_DCT_v_scaled_size; - /* Note: at the bottom of the image, we may pass extra garbage row groups - * to the postprocessor. The postprocessor has to check for bottom - * of image anyway (at row resolution), so no point in us doing it too. - */ - - /* Feed the postprocessor */ - (*cinfo->post->post_process_data) (cinfo, main->buffer, - &main->rowgroup_ctr, rowgroups_avail, - output_buf, out_row_ctr, out_rows_avail); - - /* Has postprocessor consumed all the data yet? If so, mark buffer empty */ - if (main->rowgroup_ctr >= rowgroups_avail) { - main->buffer_full = FALSE; - main->rowgroup_ctr = 0; - } -} - - -/* - * Process some data. - * This handles the case where context rows must be provided. - */ - -METHODDEF(void) -process_data_context_main (j_decompress_ptr cinfo, - JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, - JDIMENSION out_rows_avail) -{ - my_main_ptr main = (my_main_ptr) cinfo->main; - - /* Read input data if we haven't filled the main buffer yet */ - if (! main->buffer_full) { - if (! (*cinfo->coef->decompress_data) (cinfo, - main->xbuffer[main->whichptr])) - return; /* suspension forced, can do nothing more */ - main->buffer_full = TRUE; /* OK, we have an iMCU row to work with */ - main->iMCU_row_ctr++; /* count rows received */ - } - - /* Postprocessor typically will not swallow all the input data it is handed - * in one call (due to filling the output buffer first). Must be prepared - * to exit and restart. This switch lets us keep track of how far we got. - * Note that each case falls through to the next on successful completion. - */ - switch (main->context_state) { - case CTX_POSTPONED_ROW: - /* Call postprocessor using previously set pointers for postponed row */ - (*cinfo->post->post_process_data) (cinfo, main->xbuffer[main->whichptr], - &main->rowgroup_ctr, main->rowgroups_avail, - output_buf, out_row_ctr, out_rows_avail); - if (main->rowgroup_ctr < main->rowgroups_avail) - return; /* Need to suspend */ - main->context_state = CTX_PREPARE_FOR_IMCU; - if (*out_row_ctr >= out_rows_avail) - return; /* Postprocessor exactly filled output buf */ - /*FALLTHROUGH*/ - case CTX_PREPARE_FOR_IMCU: - /* Prepare to process first M-1 row groups of this iMCU row */ - main->rowgroup_ctr = 0; - main->rowgroups_avail = (JDIMENSION) (cinfo->min_DCT_v_scaled_size - 1); - /* Check for bottom of image: if so, tweak pointers to "duplicate" - * the last sample row, and adjust rowgroups_avail to ignore padding rows. - */ - if (main->iMCU_row_ctr == cinfo->total_iMCU_rows) - set_bottom_pointers(cinfo); - main->context_state = CTX_PROCESS_IMCU; - /*FALLTHROUGH*/ - case CTX_PROCESS_IMCU: - /* Call postprocessor using previously set pointers */ - (*cinfo->post->post_process_data) (cinfo, main->xbuffer[main->whichptr], - &main->rowgroup_ctr, main->rowgroups_avail, - output_buf, out_row_ctr, out_rows_avail); - if (main->rowgroup_ctr < main->rowgroups_avail) - return; /* Need to suspend */ - /* After the first iMCU, change wraparound pointers to normal state */ - if (main->iMCU_row_ctr == 1) - set_wraparound_pointers(cinfo); - /* Prepare to load new iMCU row using other xbuffer list */ - main->whichptr ^= 1; /* 0=>1 or 1=>0 */ - main->buffer_full = FALSE; - /* Still need to process last row group of this iMCU row, */ - /* which is saved at index M+1 of the other xbuffer */ - main->rowgroup_ctr = (JDIMENSION) (cinfo->min_DCT_v_scaled_size + 1); - main->rowgroups_avail = (JDIMENSION) (cinfo->min_DCT_v_scaled_size + 2); - main->context_state = CTX_POSTPONED_ROW; - } -} - - -/* - * Process some data. - * Final pass of two-pass quantization: just call the postprocessor. - * Source data will be the postprocessor controller's internal buffer. - */ - -#ifdef QUANT_2PASS_SUPPORTED - -METHODDEF(void) -process_data_crank_post (j_decompress_ptr cinfo, - JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, - JDIMENSION out_rows_avail) -{ - (*cinfo->post->post_process_data) (cinfo, (JSAMPIMAGE) NULL, - (JDIMENSION *) NULL, (JDIMENSION) 0, - output_buf, out_row_ctr, out_rows_avail); -} - -#endif /* QUANT_2PASS_SUPPORTED */ - - -/* - * Initialize main buffer controller. - */ - -GLOBAL(void) -jinit_d_main_controller (j_decompress_ptr cinfo, boolean need_full_buffer) -{ - my_main_ptr main; - int ci, rgroup, ngroups; - jpeg_component_info *compptr; - - main = (my_main_ptr) - (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, - SIZEOF(my_main_controller)); - cinfo->main = (struct jpeg_d_main_controller *) main; - main->pub.start_pass = start_pass_main; - - if (need_full_buffer) /* shouldn't happen */ - ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); - - /* Allocate the workspace. - * ngroups is the number of row groups we need. - */ - if (cinfo->upsample->need_context_rows) { - if (cinfo->min_DCT_v_scaled_size < 2) /* unsupported, see comments above */ - ERREXIT(cinfo, JERR_NOTIMPL); - alloc_funny_pointers(cinfo); /* Alloc space for xbuffer[] lists */ - ngroups = cinfo->min_DCT_v_scaled_size + 2; - } else { - ngroups = cinfo->min_DCT_v_scaled_size; - } - - for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; - ci++, compptr++) { - rgroup = (compptr->v_samp_factor * compptr->DCT_v_scaled_size) / - cinfo->min_DCT_v_scaled_size; /* height of a row group of component */ - main->buffer[ci] = (*cinfo->mem->alloc_sarray) - ((j_common_ptr) cinfo, JPOOL_IMAGE, - compptr->width_in_blocks * compptr->DCT_h_scaled_size, - (JDIMENSION) (rgroup * ngroups)); - } -} |