/* * 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, 2015-2016, 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 "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; if (cinfo->global_state != DSTATE_SCANNING || 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. */ 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; /* 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++) { /* 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 * compptr->h_samp_factor) / (long) align; cinfo->master->last_MCU_col[ci] = (JDIMENSION) jdiv_round_up((long) ((*xoffset + cinfo->output_width) * compptr->h_samp_factor), (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) { } /* * 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; void (*color_convert) (j_decompress_ptr cinfo, JSAMPIMAGE input_buf, JDIMENSION input_row, JSAMPARRAY output_buf, int num_rows); color_convert = cinfo->cconvert->color_convert; cinfo->cconvert->color_convert = noop_convert; for (n = 0; n < num_lines; n++) jpeg_read_scanlines(cinfo, NULL, 1); cinfo->cconvert->color_convert = color_convert; } /* * 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; /* 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_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; 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) { cinfo->output_scanline = cinfo->output_height; return cinfo->output_height - cinfo->output_scanline; } 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; 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; 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) { 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_after_iMCU_row / 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); } 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. */ (*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. */ 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 */