ref: f35d5ee5b036b7b4fa59b1839f52fca15b7f99f9
dir: /sys/src/cmd/gs/jpeg/jdapistd.c/
/* * jdapistd.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 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. */ #define JPEG_INTERNALS #include "jinclude.h" #include "jpeglib.h" /* Forward declarations */ LOCAL(boolean) output_pass_setup JPP((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; } /* * 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; } /* * 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 */