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libjpeg-turbo/jdmaster.c
Thomas G. Lane 36a4ccccd3 The Independent JPEG Group's JPEG software v5
2015-07-29 15:28:00 -05:00

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/*
* jdmaster.c
*
* Copyright (C) 1991-1994, 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 master control logic for the JPEG decompressor.
* These routines are concerned with selecting the modules to be executed
* and with determining the number of passes and the work to be done in each
* pass.
*/
#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
/* Private state */
typedef enum {
main_pass, /* read and process a single-scan file */
preread_pass, /* read one scan of a multi-scan file */
output_pass, /* primary processing pass for multi-scan */
post_pass /* optional post-pass for 2-pass quant. */
} D_PASS_TYPE;
typedef struct {
struct jpeg_decomp_master pub; /* public fields */
boolean using_merged_upsample; /* TRUE if using merged upsample/cconvert */
D_PASS_TYPE pass_type; /* the type of the current pass */
int pass_number; /* # of passes completed */
int total_passes; /* estimated total # of passes needed */
boolean need_post_pass; /* are we using full two-pass quantization? */
} my_decomp_master;
typedef my_decomp_master * my_master_ptr;
/*
* Determine whether merged upsample/color conversion should be used.
* CRUCIAL: this must match the actual capabilities of jdmerge.c!
*/
LOCAL boolean
use_merged_upsample (j_decompress_ptr cinfo)
{
#ifdef UPSAMPLE_MERGING_SUPPORTED
/* Merging is the equivalent of plain box-filter upsampling */
if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling)
return FALSE;
/* jdmerge.c only supports YCC=>RGB color conversion */
if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
cinfo->out_color_space != JCS_RGB ||
cinfo->out_color_components != RGB_PIXELSIZE)
return FALSE;
/* and it only handles 2h1v or 2h2v sampling ratios */
if (cinfo->comp_info[0].h_samp_factor != 2 ||
cinfo->comp_info[1].h_samp_factor != 1 ||
cinfo->comp_info[2].h_samp_factor != 1 ||
cinfo->comp_info[0].v_samp_factor > 2 ||
cinfo->comp_info[1].v_samp_factor != 1 ||
cinfo->comp_info[2].v_samp_factor != 1)
return FALSE;
/* furthermore, it doesn't work if we've scaled the IDCTs differently */
if (cinfo->comp_info[0].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
cinfo->comp_info[1].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
cinfo->comp_info[2].DCT_scaled_size != cinfo->min_DCT_scaled_size)
return FALSE;
/* ??? also need to test for upsample-time rescaling, when & if supported */
/* by golly, it'll work... */
return TRUE;
#else
return FALSE;
#endif
}
/*
* Support routines that do various essential calculations.
*
* jpeg_calc_output_dimensions is exported for possible use by application.
* Hence it mustn't do anything that can't be done twice.
*/
GLOBAL void
jpeg_calc_output_dimensions (j_decompress_ptr cinfo)
/* Do computations that are needed before master selection phase */
{
int ci;
jpeg_component_info *compptr;
/* Compute maximum sampling factors; check factor validity */
cinfo->max_h_samp_factor = 1;
cinfo->max_v_samp_factor = 1;
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
ci++, compptr++) {
if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||
compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)
ERREXIT(cinfo, JERR_BAD_SAMPLING);
cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
compptr->h_samp_factor);
cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
compptr->v_samp_factor);
}
/* Compute actual output image dimensions and DCT scaling choices. */
#ifdef IDCT_SCALING_SUPPORTED
if (cinfo->scale_num * 8 <= cinfo->scale_denom) {
/* Provide 1/8 scaling */
cinfo->output_width = (JDIMENSION)
jdiv_round_up((long) cinfo->image_width, 8L);
cinfo->output_height = (JDIMENSION)
jdiv_round_up((long) cinfo->image_height, 8L);
cinfo->min_DCT_scaled_size = 1;
} else if (cinfo->scale_num * 4 <= cinfo->scale_denom) {
/* Provide 1/4 scaling */
cinfo->output_width = (JDIMENSION)
jdiv_round_up((long) cinfo->image_width, 4L);
cinfo->output_height = (JDIMENSION)
jdiv_round_up((long) cinfo->image_height, 4L);
cinfo->min_DCT_scaled_size = 2;
} else if (cinfo->scale_num * 2 <= cinfo->scale_denom) {
/* Provide 1/2 scaling */
cinfo->output_width = (JDIMENSION)
jdiv_round_up((long) cinfo->image_width, 2L);
cinfo->output_height = (JDIMENSION)
jdiv_round_up((long) cinfo->image_height, 2L);
cinfo->min_DCT_scaled_size = 4;
} else {
/* Provide 1/1 scaling */
cinfo->output_width = cinfo->image_width;
cinfo->output_height = cinfo->image_height;
cinfo->min_DCT_scaled_size = DCTSIZE;
}
/* In selecting the actual DCT scaling for each component, we try to
* scale up the chroma components via IDCT scaling rather than upsampling.
* This saves time if the upsampler gets to use 1:1 scaling.
* Note this code assumes that the supported DCT scalings are powers of 2.
*/
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
ci++, compptr++) {
int ssize = cinfo->min_DCT_scaled_size;
while (ssize < DCTSIZE &&
(compptr->h_samp_factor * ssize * 2 <=
cinfo->max_h_samp_factor * cinfo->min_DCT_scaled_size) &&
(compptr->v_samp_factor * ssize * 2 <=
cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size)) {
ssize = ssize * 2;
}
compptr->DCT_scaled_size = ssize;
}
#else /* !IDCT_SCALING_SUPPORTED */
/* Hardwire it to "no scaling" */
cinfo->output_width = cinfo->image_width;
cinfo->output_height = cinfo->image_height;
cinfo->min_DCT_scaled_size = DCTSIZE;
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
ci++, compptr++) {
compptr->DCT_scaled_size = DCTSIZE;
}
#endif /* IDCT_SCALING_SUPPORTED */
/* Report number of components in selected colorspace. */
/* Probably this should be in the color conversion module... */
switch (cinfo->out_color_space) {
case JCS_GRAYSCALE:
cinfo->out_color_components = 1;
break;
case JCS_RGB:
#if RGB_PIXELSIZE != 3
cinfo->out_color_components = RGB_PIXELSIZE;
break;
#endif /* else share code with YCbCr */
case JCS_YCbCr:
cinfo->out_color_components = 3;
break;
case JCS_CMYK:
case JCS_YCCK:
cinfo->out_color_components = 4;
break;
default: /* else must be same colorspace as in file */
cinfo->out_color_components = cinfo->num_components;
break;
}
cinfo->output_components = (cinfo->quantize_colors ? 1 :
cinfo->out_color_components);
/* See if upsampler will want to emit more than one row at a time */
if (use_merged_upsample(cinfo))
cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
else
cinfo->rec_outbuf_height = 1;
/* Compute various sampling-related dimensions.
* Some of these are of interest to the application if it is dealing with
* "raw" (not upsampled) output, so we do the calculations here.
*/
/* Compute dimensions of components */
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
ci++, compptr++) {
/* Size in DCT blocks */
compptr->width_in_blocks = (JDIMENSION)
jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
(long) (cinfo->max_h_samp_factor * DCTSIZE));
compptr->height_in_blocks = (JDIMENSION)
jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
(long) (cinfo->max_v_samp_factor * DCTSIZE));
/* Size in samples, after IDCT scaling */
compptr->downsampled_width = (JDIMENSION)
jdiv_round_up((long) cinfo->image_width *
(long) (compptr->h_samp_factor * compptr->DCT_scaled_size),
(long) (cinfo->max_h_samp_factor * DCTSIZE));
compptr->downsampled_height = (JDIMENSION)
jdiv_round_up((long) cinfo->image_height *
(long) (compptr->v_samp_factor * compptr->DCT_scaled_size),
(long) (cinfo->max_v_samp_factor * DCTSIZE));
/* Mark component needed, until color conversion says otherwise */
compptr->component_needed = TRUE;
}
/* Compute number of fully interleaved MCU rows (number of times that
* main controller will call coefficient controller).
*/
cinfo->total_iMCU_rows = (JDIMENSION)
jdiv_round_up((long) cinfo->image_height,
(long) (cinfo->max_v_samp_factor*DCTSIZE));
}
LOCAL void
per_scan_setup (j_decompress_ptr cinfo)
/* Do computations that are needed before processing a JPEG scan */
/* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */
{
int ci, mcublks, tmp;
jpeg_component_info *compptr;
if (cinfo->comps_in_scan == 1) {
/* Noninterleaved (single-component) scan */
compptr = cinfo->cur_comp_info[0];
/* Overall image size in MCUs */
cinfo->MCUs_per_row = compptr->width_in_blocks;
cinfo->MCU_rows_in_scan = compptr->height_in_blocks;
/* For noninterleaved scan, always one block per MCU */
compptr->MCU_width = 1;
compptr->MCU_height = 1;
compptr->MCU_blocks = 1;
compptr->MCU_sample_width = compptr->DCT_scaled_size;
compptr->last_col_width = 1;
compptr->last_row_height = 1;
/* Prepare array describing MCU composition */
cinfo->blocks_in_MCU = 1;
cinfo->MCU_membership[0] = 0;
} else {
/* Interleaved (multi-component) scan */
if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
MAX_COMPS_IN_SCAN);
/* Overall image size in MCUs */
cinfo->MCUs_per_row = (JDIMENSION)
jdiv_round_up((long) cinfo->image_width,
(long) (cinfo->max_h_samp_factor*DCTSIZE));
cinfo->MCU_rows_in_scan = (JDIMENSION)
jdiv_round_up((long) cinfo->image_height,
(long) (cinfo->max_v_samp_factor*DCTSIZE));
cinfo->blocks_in_MCU = 0;
for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
compptr = cinfo->cur_comp_info[ci];
/* Sampling factors give # of blocks of component in each MCU */
compptr->MCU_width = compptr->h_samp_factor;
compptr->MCU_height = compptr->v_samp_factor;
compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_scaled_size;
/* Figure number of non-dummy blocks in last MCU column & row */
tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
if (tmp == 0) tmp = compptr->MCU_width;
compptr->last_col_width = tmp;
tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
if (tmp == 0) tmp = compptr->MCU_height;
compptr->last_row_height = tmp;
/* Prepare array describing MCU composition */
mcublks = compptr->MCU_blocks;
if (cinfo->blocks_in_MCU + mcublks > MAX_BLOCKS_IN_MCU)
ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
while (mcublks-- > 0) {
cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
}
}
}
}
/*
* Several decompression processes need to range-limit values to the range
* 0..MAXJSAMPLE; the input value may fall somewhat outside this range
* due to noise introduced by quantization, roundoff error, etc. These
* processes are inner loops and need to be as fast as possible. On most
* machines, particularly CPUs with pipelines or instruction prefetch,
* a (subscript-check-less) C table lookup
* x = sample_range_limit[x];
* is faster than explicit tests
* if (x < 0) x = 0;
* else if (x > MAXJSAMPLE) x = MAXJSAMPLE;
* These processes all use a common table prepared by the routine below.
*
* For most steps we can mathematically guarantee that the initial value
* of x is within MAXJSAMPLE+1 of the legal range, so a table running from
* -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient. But for the initial
* limiting step (just after the IDCT), a wildly out-of-range value is
* possible if the input data is corrupt. To avoid any chance of indexing
* off the end of memory and getting a bad-pointer trap, we perform the
* post-IDCT limiting thus:
* x = range_limit[x & MASK];
* where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
* samples. Under normal circumstances this is more than enough range and
* a correct output will be generated; with bogus input data the mask will
* cause wraparound, and we will safely generate a bogus-but-in-range output.
* For the post-IDCT step, we want to convert the data from signed to unsigned
* representation by adding CENTERJSAMPLE at the same time that we limit it.
* So the post-IDCT limiting table ends up looking like this:
* CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
* MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
* 0 (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
* 0,1,...,CENTERJSAMPLE-1
* Negative inputs select values from the upper half of the table after
* masking.
*
* We can save some space by overlapping the start of the post-IDCT table
* with the simpler range limiting table. The post-IDCT table begins at
* sample_range_limit + CENTERJSAMPLE.
*
* Note that the table is allocated in near data space on PCs; it's small
* enough and used often enough to justify this.
*/
LOCAL void
prepare_range_limit_table (j_decompress_ptr cinfo)
/* Allocate and fill in the sample_range_limit table */
{
JSAMPLE * table;
int i;
table = (JSAMPLE *)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
(5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE));
table += (MAXJSAMPLE+1); /* allow negative subscripts of simple table */
cinfo->sample_range_limit = table;
/* First segment of "simple" table: limit[x] = 0 for x < 0 */
MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
/* Main part of "simple" table: limit[x] = x */
for (i = 0; i <= MAXJSAMPLE; i++)
table[i] = (JSAMPLE) i;
table += CENTERJSAMPLE; /* Point to where post-IDCT table starts */
/* End of simple table, rest of first half of post-IDCT table */
for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++)
table[i] = MAXJSAMPLE;
/* Second half of post-IDCT table */
MEMZERO(table + (2 * (MAXJSAMPLE+1)),
(2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE));
MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE),
cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE));
}
/*
* Master selection of decompression modules.
* This is done once at the start of processing an image. We determine
* which modules will be used and give them appropriate initialization calls.
*
* Note that this is called only after jpeg_read_header has finished.
* We therefore know what is in the SOF and (first) SOS markers.
*/
LOCAL void
master_selection (j_decompress_ptr cinfo)
{
my_master_ptr master = (my_master_ptr) cinfo->master;
long samplesperrow;
JDIMENSION jd_samplesperrow;
/* Initialize dimensions and other stuff */
jpeg_calc_output_dimensions(cinfo);
prepare_range_limit_table(cinfo);
/* Width of an output scanline must be representable as JDIMENSION. */
samplesperrow = (long) cinfo->output_width * (long) cinfo->out_color_components;
jd_samplesperrow = (JDIMENSION) samplesperrow;
if ((long) jd_samplesperrow != samplesperrow)
ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
/* Initialize my private state */
master->pub.eoi_processed = FALSE;
master->pass_number = 0;
master->need_post_pass = FALSE;
if (cinfo->comps_in_scan == cinfo->num_components) {
master->pass_type = main_pass;
master->total_passes = 1;
} else {
#ifdef D_MULTISCAN_FILES_SUPPORTED
master->pass_type = preread_pass;
/* Assume there is a separate scan for each component; */
/* if partially interleaved, we'll increment pass_number appropriately */
master->total_passes = cinfo->num_components + 1;
#else
ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif
}
master->using_merged_upsample = use_merged_upsample(cinfo);
/* There's not a lot of smarts here right now, but it'll get more
* complicated when we have multiple implementations available...
*/
/* Color quantizer selection */
if (cinfo->quantize_colors) {
if (cinfo->raw_data_out)
ERREXIT(cinfo, JERR_NOTIMPL);
#ifdef QUANT_2PASS_SUPPORTED
/* 2-pass quantizer only works in 3-component color space.
* We use the "2-pass" code in a single pass if a colormap is given.
*/
if (cinfo->out_color_components != 3)
cinfo->two_pass_quantize = FALSE;
else if (cinfo->colormap != NULL)
cinfo->two_pass_quantize = TRUE;
#else
/* Force 1-pass quantize if we don't have 2-pass code compiled. */
cinfo->two_pass_quantize = FALSE;
#endif
if (cinfo->two_pass_quantize) {
#ifdef QUANT_2PASS_SUPPORTED
if (cinfo->colormap == NULL) {
master->need_post_pass = TRUE;
master->total_passes++;
}
jinit_2pass_quantizer(cinfo);
#else
ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif
} else {
#ifdef QUANT_1PASS_SUPPORTED
jinit_1pass_quantizer(cinfo);
#else
ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif
}
}
/* Post-processing: in particular, color conversion first */
if (! cinfo->raw_data_out) {
if (master->using_merged_upsample) {
#ifdef UPSAMPLE_MERGING_SUPPORTED
jinit_merged_upsampler(cinfo); /* does color conversion too */
#else
ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif
} else {
jinit_color_deconverter(cinfo);
jinit_upsampler(cinfo);
}
jinit_d_post_controller(cinfo, master->need_post_pass);
}
/* Inverse DCT */
jinit_inverse_dct(cinfo);
/* Entropy decoding: either Huffman or arithmetic coding. */
if (cinfo->arith_code) {
#ifdef D_ARITH_CODING_SUPPORTED
jinit_arith_decoder(cinfo);
#else
ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
#endif
} else
jinit_huff_decoder(cinfo);
jinit_d_coef_controller(cinfo, (master->pass_type == preread_pass));
jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */);
/* Note that main controller is initialized even in raw-data mode. */
/* We can now tell the memory manager to allocate virtual arrays. */
(*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
}
/*
* Per-pass setup.
* This is called at the beginning of each pass. We determine which modules
* will be active during this pass and give them appropriate start_pass calls.
* We also set is_last_pass to indicate whether any more passes will be
* required.
*/
METHODDEF void
prepare_for_pass (j_decompress_ptr cinfo)
{
my_master_ptr master = (my_master_ptr) cinfo->master;
switch (master->pass_type) {
case main_pass:
/* Set up to read and decompress single-scan file in one pass */
per_scan_setup(cinfo);
master->pub.is_last_pass = ! master->need_post_pass;
if (! cinfo->raw_data_out) {
if (! master->using_merged_upsample)
(*cinfo->cconvert->start_pass) (cinfo);
(*cinfo->upsample->start_pass) (cinfo);
if (cinfo->quantize_colors)
(*cinfo->cquantize->start_pass) (cinfo, master->need_post_pass);
(*cinfo->post->start_pass) (cinfo,
(master->need_post_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
}
(*cinfo->idct->start_input_pass) (cinfo);
(*cinfo->idct->start_output_pass) (cinfo);
(*cinfo->entropy->start_pass) (cinfo);
(*cinfo->coef->start_pass) (cinfo, JBUF_PASS_THRU);
(*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
break;
#ifdef D_MULTISCAN_FILES_SUPPORTED
case preread_pass:
/* Read (another) scan of a multi-scan file */
per_scan_setup(cinfo);
master->pub.is_last_pass = FALSE;
(*cinfo->idct->start_input_pass) (cinfo);
(*cinfo->entropy->start_pass) (cinfo);
(*cinfo->coef->start_pass) (cinfo, JBUF_SAVE_SOURCE);
(*cinfo->main->start_pass) (cinfo, JBUF_CRANK_SOURCE);
break;
case output_pass:
/* All scans read, now do the IDCT and subsequent processing */
master->pub.is_last_pass = ! master->need_post_pass;
if (! cinfo->raw_data_out) {
if (! master->using_merged_upsample)
(*cinfo->cconvert->start_pass) (cinfo);
(*cinfo->upsample->start_pass) (cinfo);
if (cinfo->quantize_colors)
(*cinfo->cquantize->start_pass) (cinfo, master->need_post_pass);
(*cinfo->post->start_pass) (cinfo,
(master->need_post_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
}
(*cinfo->idct->start_output_pass) (cinfo);
(*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST);
(*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
break;
#endif /* D_MULTISCAN_FILES_SUPPORTED */
#ifdef QUANT_2PASS_SUPPORTED
case post_pass:
/* Final pass of 2-pass quantization */
master->pub.is_last_pass = TRUE;
(*cinfo->cquantize->start_pass) (cinfo, FALSE);
(*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST);
(*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST);
break;
#endif /* QUANT_2PASS_SUPPORTED */
default:
ERREXIT(cinfo, JERR_NOT_COMPILED);
}
/* Set up progress monitor's pass info if present */
if (cinfo->progress != NULL) {
cinfo->progress->completed_passes = master->pass_number;
cinfo->progress->total_passes = master->total_passes;
}
}
/*
* Finish up at end of pass.
* In multi-scan mode, we must read next scan header and set the next
* pass_type correctly for prepare_for_pass.
*/
METHODDEF void
finish_pass_master (j_decompress_ptr cinfo)
{
my_master_ptr master = (my_master_ptr) cinfo->master;
switch (master->pass_type) {
case main_pass:
case output_pass:
if (cinfo->quantize_colors)
(*cinfo->cquantize->finish_pass) (cinfo);
master->pass_number++;
master->pass_type = post_pass; /* in case need_post_pass is true */
break;
#ifdef D_MULTISCAN_FILES_SUPPORTED
case preread_pass:
/* Count one pass done for each component in this scan */
master->pass_number += cinfo->comps_in_scan;
switch ((*cinfo->marker->read_markers) (cinfo)) {
case JPEG_HEADER_OK: /* Found SOS, do another preread pass */
break;
case JPEG_HEADER_TABLES_ONLY: /* Found EOI, no more preread passes */
master->pub.eoi_processed = TRUE;
master->pass_type = output_pass;
break;
case JPEG_SUSPENDED:
ERREXIT(cinfo, JERR_CANT_SUSPEND);
}
break;
#endif /* D_MULTISCAN_FILES_SUPPORTED */
#ifdef QUANT_2PASS_SUPPORTED
case post_pass:
(*cinfo->cquantize->finish_pass) (cinfo);
/* there will be no more passes, don't bother to change state */
break;
#endif /* QUANT_2PASS_SUPPORTED */
default:
ERREXIT(cinfo, JERR_NOT_COMPILED);
}
}
/*
* Initialize master decompression control.
* This creates my own subrecord and also performs the master selection phase,
* which causes other modules to create their subrecords.
*/
GLOBAL void
jinit_master_decompress (j_decompress_ptr cinfo)
{
my_master_ptr master;
master = (my_master_ptr)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
SIZEOF(my_decomp_master));
cinfo->master = (struct jpeg_decomp_master *) master;
master->pub.prepare_for_pass = prepare_for_pass;
master->pub.finish_pass = finish_pass_master;
master_selection(cinfo);
}
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