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Diffstat (limited to 'media/libjpeg/jdapistd.c')
| -rw-r--r-- | media/libjpeg/jdapistd.c | 689 |
1 files changed, 689 insertions, 0 deletions
diff --git a/media/libjpeg/jdapistd.c b/media/libjpeg/jdapistd.c new file mode 100644 index 0000000000..02cd0cb93a --- /dev/null +++ b/media/libjpeg/jdapistd.c @@ -0,0 +1,689 @@ +/* + * jdapistd.c + * + * This file was part of the Independent JPEG Group's software: + * Copyright (C) 1994-1996, Thomas G. Lane. + * libjpeg-turbo Modifications: + * Copyright (C) 2010, 2015-2020, 2022, D. R. Commander. + * Copyright (C) 2015, Google, Inc. + * For conditions of distribution and use, see the accompanying README.ijg + * file. + * + * This file contains application interface code for the decompression half + * of the JPEG library. These are the "standard" API routines that are + * used in the normal full-decompression case. They are not used by a + * transcoding-only application. Note that if an application links in + * jpeg_start_decompress, it will end up linking in the entire decompressor. + * We thus must separate this file from jdapimin.c to avoid linking the + * whole decompression library into a transcoder. + */ + +#include "jinclude.h" +#include "jdmainct.h" +#include "jdcoefct.h" +#include "jdmaster.h" +#include "jdmerge.h" +#include "jdsample.h" +#include "jmemsys.h" + +/* Forward declarations */ +LOCAL(boolean) output_pass_setup(j_decompress_ptr cinfo); + + +/* + * Decompression initialization. + * jpeg_read_header must be completed before calling this. + * + * If a multipass operating mode was selected, this will do all but the + * last pass, and thus may take a great deal of time. + * + * Returns FALSE if suspended. The return value need be inspected only if + * a suspending data source is used. + */ + +GLOBAL(boolean) +jpeg_start_decompress(j_decompress_ptr cinfo) +{ + if (cinfo->global_state == DSTATE_READY) { + /* First call: initialize master control, select active modules */ + jinit_master_decompress(cinfo); + if (cinfo->buffered_image) { + /* No more work here; expecting jpeg_start_output next */ + cinfo->global_state = DSTATE_BUFIMAGE; + return TRUE; + } + cinfo->global_state = DSTATE_PRELOAD; + } + if (cinfo->global_state == DSTATE_PRELOAD) { + /* If file has multiple scans, absorb them all into the coef buffer */ + if (cinfo->inputctl->has_multiple_scans) { +#ifdef D_MULTISCAN_FILES_SUPPORTED + for (;;) { + int retcode; + /* Call progress monitor hook if present */ + if (cinfo->progress != NULL) + (*cinfo->progress->progress_monitor) ((j_common_ptr)cinfo); + /* Absorb some more input */ + retcode = (*cinfo->inputctl->consume_input) (cinfo); + if (retcode == JPEG_SUSPENDED) + return FALSE; + if (retcode == JPEG_REACHED_EOI) + break; + /* Advance progress counter if appropriate */ + if (cinfo->progress != NULL && + (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) { + if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) { + /* jdmaster underestimated number of scans; ratchet up one scan */ + cinfo->progress->pass_limit += (long)cinfo->total_iMCU_rows; + } + } + } +#else + ERREXIT(cinfo, JERR_NOT_COMPILED); +#endif /* D_MULTISCAN_FILES_SUPPORTED */ + } + cinfo->output_scan_number = cinfo->input_scan_number; + } else if (cinfo->global_state != DSTATE_PRESCAN) + ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); + /* Perform any dummy output passes, and set up for the final pass */ + return output_pass_setup(cinfo); +} + + +/* + * Set up for an output pass, and perform any dummy pass(es) needed. + * Common subroutine for jpeg_start_decompress and jpeg_start_output. + * Entry: global_state = DSTATE_PRESCAN only if previously suspended. + * Exit: If done, returns TRUE and sets global_state for proper output mode. + * If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN. + */ + +LOCAL(boolean) +output_pass_setup(j_decompress_ptr cinfo) +{ + if (cinfo->global_state != DSTATE_PRESCAN) { + /* First call: do pass setup */ + (*cinfo->master->prepare_for_output_pass) (cinfo); + cinfo->output_scanline = 0; + cinfo->global_state = DSTATE_PRESCAN; + } + /* Loop over any required dummy passes */ + while (cinfo->master->is_dummy_pass) { +#ifdef QUANT_2PASS_SUPPORTED + /* Crank through the dummy pass */ + while (cinfo->output_scanline < cinfo->output_height) { + JDIMENSION last_scanline; + /* Call progress monitor hook if present */ + if (cinfo->progress != NULL) { + cinfo->progress->pass_counter = (long)cinfo->output_scanline; + cinfo->progress->pass_limit = (long)cinfo->output_height; + (*cinfo->progress->progress_monitor) ((j_common_ptr)cinfo); + } + /* Process some data */ + last_scanline = cinfo->output_scanline; + (*cinfo->main->process_data) (cinfo, (JSAMPARRAY)NULL, + &cinfo->output_scanline, (JDIMENSION)0); + if (cinfo->output_scanline == last_scanline) + return FALSE; /* No progress made, must suspend */ + } + /* Finish up dummy pass, and set up for another one */ + (*cinfo->master->finish_output_pass) (cinfo); + (*cinfo->master->prepare_for_output_pass) (cinfo); + cinfo->output_scanline = 0; +#else + ERREXIT(cinfo, JERR_NOT_COMPILED); +#endif /* QUANT_2PASS_SUPPORTED */ + } + /* Ready for application to drive output pass through + * jpeg_read_scanlines or jpeg_read_raw_data. + */ + cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING; + return TRUE; +} + + +/* + * Enable partial scanline decompression + * + * Must be called after jpeg_start_decompress() and before any calls to + * jpeg_read_scanlines() or jpeg_skip_scanlines(). + * + * Refer to libjpeg.txt for more information. + */ + +GLOBAL(void) +jpeg_crop_scanline(j_decompress_ptr cinfo, JDIMENSION *xoffset, + JDIMENSION *width) +{ + int ci, align, orig_downsampled_width; + JDIMENSION input_xoffset; + boolean reinit_upsampler = FALSE; + jpeg_component_info *compptr; +#ifdef UPSAMPLE_MERGING_SUPPORTED + my_master_ptr master = (my_master_ptr)cinfo->master; +#endif + + if ((cinfo->global_state != DSTATE_SCANNING && + cinfo->global_state != DSTATE_BUFIMAGE) || cinfo->output_scanline != 0) + ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); + + if (!xoffset || !width) + ERREXIT(cinfo, JERR_BAD_CROP_SPEC); + + /* xoffset and width must fall within the output image dimensions. */ + if (*width == 0 || *xoffset + *width > cinfo->output_width) + ERREXIT(cinfo, JERR_WIDTH_OVERFLOW); + + /* No need to do anything if the caller wants the entire width. */ + if (*width == cinfo->output_width) + return; + + /* Ensuring the proper alignment of xoffset is tricky. At minimum, it + * must align with an MCU boundary, because: + * + * (1) The IDCT is performed in blocks, and it is not feasible to modify + * the algorithm so that it can transform partial blocks. + * (2) Because of the SIMD extensions, any input buffer passed to the + * upsampling and color conversion routines must be aligned to the + * SIMD word size (for instance, 128-bit in the case of SSE2.) The + * easiest way to accomplish this without copying data is to ensure + * that upsampling and color conversion begin at the start of the + * first MCU column that will be inverse transformed. + * + * In practice, we actually impose a stricter alignment requirement. We + * require that xoffset be a multiple of the maximum MCU column width of all + * of the components (the "iMCU column width.") This is to simplify the + * single-pass decompression case, allowing us to use the same MCU column + * width for all of the components. + */ + if (cinfo->comps_in_scan == 1 && cinfo->num_components == 1) + align = cinfo->_min_DCT_scaled_size; + else + align = cinfo->_min_DCT_scaled_size * cinfo->max_h_samp_factor; + + /* Adjust xoffset to the nearest iMCU boundary <= the requested value */ + input_xoffset = *xoffset; + *xoffset = (input_xoffset / align) * align; + + /* Adjust the width so that the right edge of the output image is as + * requested (only the left edge is altered.) It is important that calling + * programs check this value after this function returns, so that they can + * allocate an output buffer with the appropriate size. + */ + *width = *width + input_xoffset - *xoffset; + cinfo->output_width = *width; +#ifdef UPSAMPLE_MERGING_SUPPORTED + if (master->using_merged_upsample && cinfo->max_v_samp_factor == 2) { + my_merged_upsample_ptr upsample = (my_merged_upsample_ptr)cinfo->upsample; + upsample->out_row_width = + cinfo->output_width * cinfo->out_color_components; + } +#endif + + /* Set the first and last iMCU columns that we must decompress. These values + * will be used in single-scan decompressions. + */ + cinfo->master->first_iMCU_col = (JDIMENSION)(long)(*xoffset) / (long)align; + cinfo->master->last_iMCU_col = + (JDIMENSION)jdiv_round_up((long)(*xoffset + cinfo->output_width), + (long)align) - 1; + + for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; + ci++, compptr++) { + int hsf = (cinfo->comps_in_scan == 1 && cinfo->num_components == 1) ? + 1 : compptr->h_samp_factor; + + /* Set downsampled_width to the new output width. */ + orig_downsampled_width = compptr->downsampled_width; + compptr->downsampled_width = + (JDIMENSION)jdiv_round_up((long)(cinfo->output_width * + compptr->h_samp_factor), + (long)cinfo->max_h_samp_factor); + if (compptr->downsampled_width < 2 && orig_downsampled_width >= 2) + reinit_upsampler = TRUE; + + /* Set the first and last iMCU columns that we must decompress. These + * values will be used in multi-scan decompressions. + */ + cinfo->master->first_MCU_col[ci] = + (JDIMENSION)(long)(*xoffset * hsf) / (long)align; + cinfo->master->last_MCU_col[ci] = + (JDIMENSION)jdiv_round_up((long)((*xoffset + cinfo->output_width) * hsf), + (long)align) - 1; + } + + if (reinit_upsampler) { + cinfo->master->jinit_upsampler_no_alloc = TRUE; + jinit_upsampler(cinfo); + cinfo->master->jinit_upsampler_no_alloc = FALSE; + } +} + + +/* + * Read some scanlines of data from the JPEG decompressor. + * + * The return value will be the number of lines actually read. + * This may be less than the number requested in several cases, + * including bottom of image, data source suspension, and operating + * modes that emit multiple scanlines at a time. + * + * Note: we warn about excess calls to jpeg_read_scanlines() since + * this likely signals an application programmer error. However, + * an oversize buffer (max_lines > scanlines remaining) is not an error. + */ + +GLOBAL(JDIMENSION) +jpeg_read_scanlines(j_decompress_ptr cinfo, JSAMPARRAY scanlines, + JDIMENSION max_lines) +{ + JDIMENSION row_ctr; + + if (cinfo->global_state != DSTATE_SCANNING) + ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); + if (cinfo->output_scanline >= cinfo->output_height) { + WARNMS(cinfo, JWRN_TOO_MUCH_DATA); + return 0; + } + + /* Call progress monitor hook if present */ + if (cinfo->progress != NULL) { + cinfo->progress->pass_counter = (long)cinfo->output_scanline; + cinfo->progress->pass_limit = (long)cinfo->output_height; + (*cinfo->progress->progress_monitor) ((j_common_ptr)cinfo); + } + + /* Process some data */ + row_ctr = 0; + (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, max_lines); + cinfo->output_scanline += row_ctr; + return row_ctr; +} + + +/* Dummy color convert function used by jpeg_skip_scanlines() */ +LOCAL(void) +noop_convert(j_decompress_ptr cinfo, JSAMPIMAGE input_buf, + JDIMENSION input_row, JSAMPARRAY output_buf, int num_rows) +{ +} + + +/* Dummy quantize function used by jpeg_skip_scanlines() */ +LOCAL(void) +noop_quantize(j_decompress_ptr cinfo, JSAMPARRAY input_buf, + JSAMPARRAY output_buf, int num_rows) +{ +} + + +/* + * In some cases, it is best to call jpeg_read_scanlines() and discard the + * output, rather than skipping the scanlines, because this allows us to + * maintain the internal state of the context-based upsampler. In these cases, + * we set up and tear down a dummy color converter in order to avoid valgrind + * errors and to achieve the best possible performance. + */ + +LOCAL(void) +read_and_discard_scanlines(j_decompress_ptr cinfo, JDIMENSION num_lines) +{ + JDIMENSION n; +#ifdef UPSAMPLE_MERGING_SUPPORTED + my_master_ptr master = (my_master_ptr)cinfo->master; +#endif + JSAMPLE dummy_sample[1] = { 0 }; + JSAMPROW dummy_row = dummy_sample; + JSAMPARRAY scanlines = NULL; + void (*color_convert) (j_decompress_ptr cinfo, JSAMPIMAGE input_buf, + JDIMENSION input_row, JSAMPARRAY output_buf, + int num_rows) = NULL; + void (*color_quantize) (j_decompress_ptr cinfo, JSAMPARRAY input_buf, + JSAMPARRAY output_buf, int num_rows) = NULL; + + if (cinfo->cconvert && cinfo->cconvert->color_convert) { + color_convert = cinfo->cconvert->color_convert; + cinfo->cconvert->color_convert = noop_convert; + /* This just prevents UBSan from complaining about adding 0 to a NULL + * pointer. The pointer isn't actually used. + */ + scanlines = &dummy_row; + } + + if (cinfo->cquantize && cinfo->cquantize->color_quantize) { + color_quantize = cinfo->cquantize->color_quantize; + cinfo->cquantize->color_quantize = noop_quantize; + } + +#ifdef UPSAMPLE_MERGING_SUPPORTED + if (master->using_merged_upsample && cinfo->max_v_samp_factor == 2) { + my_merged_upsample_ptr upsample = (my_merged_upsample_ptr)cinfo->upsample; + scanlines = &upsample->spare_row; + } +#endif + + for (n = 0; n < num_lines; n++) + jpeg_read_scanlines(cinfo, scanlines, 1); + + if (color_convert) + cinfo->cconvert->color_convert = color_convert; + + if (color_quantize) + cinfo->cquantize->color_quantize = color_quantize; +} + + +/* + * Called by jpeg_skip_scanlines(). This partially skips a decompress block by + * incrementing the rowgroup counter. + */ + +LOCAL(void) +increment_simple_rowgroup_ctr(j_decompress_ptr cinfo, JDIMENSION rows) +{ + JDIMENSION rows_left; + my_main_ptr main_ptr = (my_main_ptr)cinfo->main; + my_master_ptr master = (my_master_ptr)cinfo->master; + + if (master->using_merged_upsample && cinfo->max_v_samp_factor == 2) { + read_and_discard_scanlines(cinfo, rows); + return; + } + + /* Increment the counter to the next row group after the skipped rows. */ + main_ptr->rowgroup_ctr += rows / cinfo->max_v_samp_factor; + + /* Partially skipping a row group would involve modifying the internal state + * of the upsampler, so read the remaining rows into a dummy buffer instead. + */ + rows_left = rows % cinfo->max_v_samp_factor; + cinfo->output_scanline += rows - rows_left; + + read_and_discard_scanlines(cinfo, rows_left); +} + +/* + * Skips some scanlines of data from the JPEG decompressor. + * + * The return value will be the number of lines actually skipped. If skipping + * num_lines would move beyond the end of the image, then the actual number of + * lines remaining in the image is returned. Otherwise, the return value will + * be equal to num_lines. + * + * Refer to libjpeg.txt for more information. + */ + +GLOBAL(JDIMENSION) +jpeg_skip_scanlines(j_decompress_ptr cinfo, JDIMENSION num_lines) +{ + my_main_ptr main_ptr = (my_main_ptr)cinfo->main; + my_coef_ptr coef = (my_coef_ptr)cinfo->coef; + my_master_ptr master = (my_master_ptr)cinfo->master; + my_upsample_ptr upsample = (my_upsample_ptr)cinfo->upsample; + JDIMENSION i, x; + int y; + JDIMENSION lines_per_iMCU_row, lines_left_in_iMCU_row, lines_after_iMCU_row; + JDIMENSION lines_to_skip, lines_to_read; + + /* Two-pass color quantization is not supported. */ + if (cinfo->quantize_colors && cinfo->two_pass_quantize) + ERREXIT(cinfo, JERR_NOTIMPL); + + if (cinfo->global_state != DSTATE_SCANNING) + ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); + + /* Do not skip past the bottom of the image. */ + if (cinfo->output_scanline + num_lines >= cinfo->output_height) { + num_lines = cinfo->output_height - cinfo->output_scanline; + cinfo->output_scanline = cinfo->output_height; + (*cinfo->inputctl->finish_input_pass) (cinfo); + cinfo->inputctl->eoi_reached = TRUE; + return num_lines; + } + + if (num_lines == 0) + return 0; + + lines_per_iMCU_row = cinfo->_min_DCT_scaled_size * cinfo->max_v_samp_factor; + lines_left_in_iMCU_row = + (lines_per_iMCU_row - (cinfo->output_scanline % lines_per_iMCU_row)) % + lines_per_iMCU_row; + lines_after_iMCU_row = num_lines - lines_left_in_iMCU_row; + + /* Skip the lines remaining in the current iMCU row. When upsampling + * requires context rows, we need the previous and next rows in order to read + * the current row. This adds some complexity. + */ + if (cinfo->upsample->need_context_rows) { + /* If the skipped lines would not move us past the current iMCU row, we + * read the lines and ignore them. There might be a faster way of doing + * this, but we are facing increasing complexity for diminishing returns. + * The increasing complexity would be a by-product of meddling with the + * state machine used to skip context rows. Near the end of an iMCU row, + * the next iMCU row may have already been entropy-decoded. In this unique + * case, we will read the next iMCU row if we cannot skip past it as well. + */ + if ((num_lines < lines_left_in_iMCU_row + 1) || + (lines_left_in_iMCU_row <= 1 && main_ptr->buffer_full && + lines_after_iMCU_row < lines_per_iMCU_row + 1)) { + read_and_discard_scanlines(cinfo, num_lines); + return num_lines; + } + + /* If the next iMCU row has already been entropy-decoded, make sure that + * we do not skip too far. + */ + if (lines_left_in_iMCU_row <= 1 && main_ptr->buffer_full) { + cinfo->output_scanline += lines_left_in_iMCU_row + lines_per_iMCU_row; + lines_after_iMCU_row -= lines_per_iMCU_row; + } else { + cinfo->output_scanline += lines_left_in_iMCU_row; + } + + /* If we have just completed the first block, adjust the buffer pointers */ + if (main_ptr->iMCU_row_ctr == 0 || + (main_ptr->iMCU_row_ctr == 1 && lines_left_in_iMCU_row > 2)) + set_wraparound_pointers(cinfo); + main_ptr->buffer_full = FALSE; + main_ptr->rowgroup_ctr = 0; + main_ptr->context_state = CTX_PREPARE_FOR_IMCU; + if (!master->using_merged_upsample) { + upsample->next_row_out = cinfo->max_v_samp_factor; + upsample->rows_to_go = cinfo->output_height - cinfo->output_scanline; + } + } + + /* Skipping is much simpler when context rows are not required. */ + else { + if (num_lines < lines_left_in_iMCU_row) { + increment_simple_rowgroup_ctr(cinfo, num_lines); + return num_lines; + } else { + cinfo->output_scanline += lines_left_in_iMCU_row; + main_ptr->buffer_full = FALSE; + main_ptr->rowgroup_ctr = 0; + if (!master->using_merged_upsample) { + upsample->next_row_out = cinfo->max_v_samp_factor; + upsample->rows_to_go = cinfo->output_height - cinfo->output_scanline; + } + } + } + + /* Calculate how many full iMCU rows we can skip. */ + if (cinfo->upsample->need_context_rows) + lines_to_skip = ((lines_after_iMCU_row - 1) / lines_per_iMCU_row) * + lines_per_iMCU_row; + else + lines_to_skip = (lines_after_iMCU_row / lines_per_iMCU_row) * + lines_per_iMCU_row; + /* Calculate the number of lines that remain to be skipped after skipping all + * of the full iMCU rows that we can. We will not read these lines unless we + * have to. + */ + lines_to_read = lines_after_iMCU_row - lines_to_skip; + + /* For images requiring multiple scans (progressive, non-interleaved, etc.), + * all of the entropy decoding occurs in jpeg_start_decompress(), assuming + * that the input data source is non-suspending. This makes skipping easy. + */ + if (cinfo->inputctl->has_multiple_scans || cinfo->buffered_image) { + if (cinfo->upsample->need_context_rows) { + cinfo->output_scanline += lines_to_skip; + cinfo->output_iMCU_row += lines_to_skip / lines_per_iMCU_row; + main_ptr->iMCU_row_ctr += lines_to_skip / lines_per_iMCU_row; + /* It is complex to properly move to the middle of a context block, so + * read the remaining lines instead of skipping them. + */ + read_and_discard_scanlines(cinfo, lines_to_read); + } else { + cinfo->output_scanline += lines_to_skip; + cinfo->output_iMCU_row += lines_to_skip / lines_per_iMCU_row; + increment_simple_rowgroup_ctr(cinfo, lines_to_read); + } + if (!master->using_merged_upsample) + upsample->rows_to_go = cinfo->output_height - cinfo->output_scanline; + return num_lines; + } + + /* Skip the iMCU rows that we can safely skip. */ + for (i = 0; i < lines_to_skip; i += lines_per_iMCU_row) { + for (y = 0; y < coef->MCU_rows_per_iMCU_row; y++) { + for (x = 0; x < cinfo->MCUs_per_row; x++) { + /* Calling decode_mcu() with a NULL pointer causes it to discard the + * decoded coefficients. This is ~5% faster for large subsets, but + * it's tough to tell a difference for smaller images. + */ + if (!cinfo->entropy->insufficient_data) + cinfo->master->last_good_iMCU_row = cinfo->input_iMCU_row; + (*cinfo->entropy->decode_mcu) (cinfo, NULL); + } + } + cinfo->input_iMCU_row++; + cinfo->output_iMCU_row++; + if (cinfo->input_iMCU_row < cinfo->total_iMCU_rows) + start_iMCU_row(cinfo); + else + (*cinfo->inputctl->finish_input_pass) (cinfo); + } + cinfo->output_scanline += lines_to_skip; + + if (cinfo->upsample->need_context_rows) { + /* Context-based upsampling keeps track of iMCU rows. */ + main_ptr->iMCU_row_ctr += lines_to_skip / lines_per_iMCU_row; + + /* It is complex to properly move to the middle of a context block, so + * read the remaining lines instead of skipping them. + */ + read_and_discard_scanlines(cinfo, lines_to_read); + } else { + increment_simple_rowgroup_ctr(cinfo, lines_to_read); + } + + /* Since skipping lines involves skipping the upsampling step, the value of + * "rows_to_go" will become invalid unless we set it here. NOTE: This is a + * bit odd, since "rows_to_go" seems to be redundantly keeping track of + * output_scanline. + */ + if (!master->using_merged_upsample) + upsample->rows_to_go = cinfo->output_height - cinfo->output_scanline; + + /* Always skip the requested number of lines. */ + return num_lines; +} + +/* + * Alternate entry point to read raw data. + * Processes exactly one iMCU row per call, unless suspended. + */ + +GLOBAL(JDIMENSION) +jpeg_read_raw_data(j_decompress_ptr cinfo, JSAMPIMAGE data, + JDIMENSION max_lines) +{ + JDIMENSION lines_per_iMCU_row; + + if (cinfo->global_state != DSTATE_RAW_OK) + ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); + if (cinfo->output_scanline >= cinfo->output_height) { + WARNMS(cinfo, JWRN_TOO_MUCH_DATA); + return 0; + } + + /* Call progress monitor hook if present */ + if (cinfo->progress != NULL) { + cinfo->progress->pass_counter = (long)cinfo->output_scanline; + cinfo->progress->pass_limit = (long)cinfo->output_height; + (*cinfo->progress->progress_monitor) ((j_common_ptr)cinfo); + } + + /* Verify that at least one iMCU row can be returned. */ + lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->_min_DCT_scaled_size; + if (max_lines < lines_per_iMCU_row) + ERREXIT(cinfo, JERR_BUFFER_SIZE); + + /* Decompress directly into user's buffer. */ + if (!(*cinfo->coef->decompress_data) (cinfo, data)) + return 0; /* suspension forced, can do nothing more */ + + /* OK, we processed one iMCU row. */ + cinfo->output_scanline += lines_per_iMCU_row; + return lines_per_iMCU_row; +} + + +/* Additional entry points for buffered-image mode. */ + +#ifdef D_MULTISCAN_FILES_SUPPORTED + +/* + * Initialize for an output pass in buffered-image mode. + */ + +GLOBAL(boolean) +jpeg_start_output(j_decompress_ptr cinfo, int scan_number) +{ + if (cinfo->global_state != DSTATE_BUFIMAGE && + cinfo->global_state != DSTATE_PRESCAN) + ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); + /* Limit scan number to valid range */ + if (scan_number <= 0) + scan_number = 1; + if (cinfo->inputctl->eoi_reached && scan_number > cinfo->input_scan_number) + scan_number = cinfo->input_scan_number; + cinfo->output_scan_number = scan_number; + /* Perform any dummy output passes, and set up for the real pass */ + return output_pass_setup(cinfo); +} + + +/* + * Finish up after an output pass in buffered-image mode. + * + * Returns FALSE if suspended. The return value need be inspected only if + * a suspending data source is used. + */ + +GLOBAL(boolean) +jpeg_finish_output(j_decompress_ptr cinfo) +{ + if ((cinfo->global_state == DSTATE_SCANNING || + cinfo->global_state == DSTATE_RAW_OK) && cinfo->buffered_image) { + /* Terminate this pass. */ + /* We do not require the whole pass to have been completed. */ + (*cinfo->master->finish_output_pass) (cinfo); + cinfo->global_state = DSTATE_BUFPOST; + } else if (cinfo->global_state != DSTATE_BUFPOST) { + /* BUFPOST = repeat call after a suspension, anything else is error */ + ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state); + } + /* Read markers looking for SOS or EOI */ + while (cinfo->input_scan_number <= cinfo->output_scan_number && + !cinfo->inputctl->eoi_reached) { + if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED) + return FALSE; /* Suspend, come back later */ + } + cinfo->global_state = DSTATE_BUFIMAGE; + return TRUE; +} + +#endif /* D_MULTISCAN_FILES_SUPPORTED */ |