/*
* jdmaster.c
*
* Copyright (C) 1991-1995, 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 struct {
struct jpeg_decomp_master pub;/* public fields */
int pass_number; /* # of passes completed */
boolean using_merged_upsample;/* TRUE if using merged upsample/cconvert */
/* Saved references to initialized quantizer modules,
* in case we need to switch modes.
*/
struct jpeg_color_quantizer * quantizer_1pass;
struct jpeg_color_quantizer * quantizer_2pass;
} 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 */
return TRUE; /* by golly, it'll work... */
#else
return FALSE;
#endif
}
/*
* Compute output image dimensions and related values.
* NOTE: this is exported for possible use by application.
* Hence it mustn't do anything that can't be done twice.
* Also note that it may be called before the master module is initialized!
*/
GLOBAL void
jpeg_calc_output_dimensions( j_decompress_ptr cinfo ) {
/* Do computations that are needed before master selection phase */
#if 0 // JDC: commented out to remove warning
int ci;
jpeg_component_info * compptr;
#endif
/* Prevent application from calling me at wrong times */
if ( cinfo->global_state != DSTATE_READY ) {
ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
}
#ifdef IDCT_SCALING_SUPPORTED
/* Compute actual output image dimensions and DCT scaling choices. */
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;
}
/* Recompute downsampled dimensions of components;
* application needs to know these if using raw downsampled data.
*/
for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
ci++, compptr++ ) {
/* 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 ) );
}
#else /* !IDCT_SCALING_SUPPORTED */
/* Hardwire it to "no scaling" */
cinfo->output_width = cinfo->image_width;
cinfo->output_height = cinfo->image_height;
/* jdinput.c has already initialized DCT_scaled_size to DCTSIZE,
* and has computed unscaled downsampled_width and downsampled_height.
*/
#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;
}
}
/*
* 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 jpeg_start_decompress time. We determine
* which modules will be used and give them appropriate initialization calls.
* We also initialize the decompressor input side to begin consuming data.
*
* Since jpeg_read_header has finished, we know what is in the SOF
* and (first) SOS markers. We also have all the application parameter
* settings.
*/
LOCAL void
master_selection( j_decompress_ptr cinfo ) {
my_master_ptr master = (my_master_ptr) cinfo->master;
boolean use_c_buffer;
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->pass_number = 0;
master->using_merged_upsample = use_merged_upsample( cinfo );
/* Color quantizer selection */
master->quantizer_1pass = NULL;
master->quantizer_2pass = NULL;
/* No mode changes if not using buffered-image mode. */
if ( ( !cinfo->quantize_colors ) || ( !cinfo->buffered_image ) ) {
cinfo->enable_1pass_quant = FALSE;
cinfo->enable_external_quant = FALSE;
cinfo->enable_2pass_quant = FALSE;
}
if ( cinfo->quantize_colors ) {
if ( cinfo->raw_data_out ) {
ERREXIT( cinfo, JERR_NOTIMPL );
}
/* 2-pass quantizer only works in 3-component color space. */
if ( cinfo->out_color_components != 3 ) {
cinfo->enable_1pass_quant = TRUE;
cinfo->enable_external_quant = FALSE;
cinfo->enable_2pass_quant = FALSE;
cinfo->colormap = NULL;
} else if ( cinfo->colormap != NULL ) {
cinfo->enable_external_quant = TRUE;
} else if ( cinfo->two_pass_quantize ) {
cinfo->enable_2pass_quant = TRUE;
} else {
cinfo->enable_1pass_quant = TRUE;
}
if ( cinfo->enable_1pass_quant ) {
#ifdef QUANT_1PASS_SUPPORTED
jinit_1pass_quantizer( cinfo );
master->quantizer_1pass = cinfo->cquantize;
#else
ERREXIT( cinfo, JERR_NOT_COMPILED );
#endif
}
/* We use the 2-pass code to map to external colormaps. */
if ( ( cinfo->enable_2pass_quant ) || ( cinfo->enable_external_quant ) ) {
#ifdef QUANT_2PASS_SUPPORTED
jinit_2pass_quantizer( cinfo );
master->quantizer_2pass = cinfo->cquantize;
#else
ERREXIT( cinfo, JERR_NOT_COMPILED );
#endif
}
/* If both quantizers are initialized, the 2-pass one is left active;
* this is necessary for starting with quantization to an external map.
*/
}
/* 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, cinfo->enable_2pass_quant );
}
/* Inverse DCT */
jinit_inverse_dct( cinfo );
/* Entropy decoding: either Huffman or arithmetic coding. */
if ( cinfo->arith_code ) {
ERREXIT( cinfo, JERR_ARITH_NOTIMPL );
} else {
if ( cinfo->progressive_mode ) {
#ifdef D_PROGRESSIVE_SUPPORTED
jinit_phuff_decoder( cinfo );
#else
ERREXIT( cinfo, JERR_NOT_COMPILED );
#endif
} else {
jinit_huff_decoder( cinfo );
}
}
/* Initialize principal buffer controllers. */
use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
jinit_d_coef_controller( cinfo, use_c_buffer );
if ( !cinfo->raw_data_out ) {
jinit_d_main_controller( cinfo, FALSE /* never need full buffer here */ );
}
/* We can now tell the memory manager to allocate virtual arrays. */
( *cinfo->mem->realize_virt_arrays )( (j_common_ptr) cinfo );
/* Initialize input side of decompressor to consume first scan. */
( *cinfo->inputctl->start_input_pass )( cinfo );
#ifdef D_MULTISCAN_FILES_SUPPORTED
/* If jpeg_start_decompress will read the whole file, initialize
* progress monitoring appropriately. The input step is counted
* as one pass.
*/
if ( ( cinfo->progress != NULL ) && ( !cinfo->buffered_image ) &&
( cinfo->inputctl->has_multiple_scans ) ) {
int nscans;
/* Estimate number of scans to set pass_limit. */
if ( cinfo->progressive_mode ) {
/* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
nscans = 2 + 3 * cinfo->num_components;
} else {
/* For a nonprogressive multiscan file, estimate 1 scan per component. */
nscans = cinfo->num_components;
}
cinfo->progress->pass_counter = 0L;
cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
cinfo->progress->completed_passes = 0;
cinfo->progress->total_passes = ( cinfo->enable_2pass_quant ? 3 : 2 );
/* Count the input pass as done */
master->pass_number++;
}
#endif /* D_MULTISCAN_FILES_SUPPORTED */
}
/*
* Per-pass setup.
* This is called at the beginning of each output pass. We determine which
* modules will be active during this pass and give them appropriate
* start_pass calls. We also set is_dummy_pass to indicate whether this
* is a "real" output pass or a dummy pass for color quantization.
* (In the latter case, jdapi.c will crank the pass to completion.)
*/
METHODDEF void
prepare_for_output_pass( j_decompress_ptr cinfo ) {
my_master_ptr master = (my_master_ptr) cinfo->master;
if ( master->pub.is_dummy_pass ) {
#ifdef QUANT_2PASS_SUPPORTED
/* Final pass of 2-pass quantization */
master->pub.is_dummy_pass = FALSE;
( *cinfo->cquantize->start_pass )( cinfo, FALSE );
( *cinfo->post->start_pass )( cinfo, JBUF_CRANK_DEST );
( *cinfo->main->start_pass )( cinfo, JBUF_CRANK_DEST );
#else
ERREXIT( cinfo, JERR_NOT_COMPILED );
#endif /* QUANT_2PASS_SUPPORTED */
} else {
if ( ( cinfo->quantize_colors ) && ( cinfo->colormap == NULL ) ) {
/* Select new quantization method */
if ( ( cinfo->two_pass_quantize ) && ( cinfo->enable_2pass_quant ) ) {
cinfo->cquantize = master->quantizer_2pass;
master->pub.is_dummy_pass = TRUE;
} else if ( cinfo->enable_1pass_quant ) {
cinfo->cquantize = master->quantizer_1pass;
} else {
ERREXIT( cinfo, JERR_MODE_CHANGE );
}
}
( *cinfo->idct->start_pass )( cinfo );
( *cinfo->coef->start_output_pass )( cinfo );
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->pub.is_dummy_pass );
}
( *cinfo->post->start_pass )( cinfo,
( master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU ) );
( *cinfo->main->start_pass )( cinfo, JBUF_PASS_THRU );
}
}
/* 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->pass_number +
( master->pub.is_dummy_pass ? 2 : 1 );
/* In buffered-image mode, we assume one more output pass if EOI not
* yet reached, but no more passes if EOI has been reached.
*/
if ( ( cinfo->buffered_image ) && ( !cinfo->inputctl->eoi_reached ) ) {
cinfo->progress->total_passes += ( cinfo->enable_2pass_quant ? 2 : 1 );
}
}
}
/*
* Finish up at end of an output pass.
*/
METHODDEF void
finish_output_pass( j_decompress_ptr cinfo ) {
my_master_ptr master = (my_master_ptr) cinfo->master;
if ( cinfo->quantize_colors ) {
( *cinfo->cquantize->finish_pass )( cinfo );
}
master->pass_number++;
}
#ifdef D_MULTISCAN_FILES_SUPPORTED
/*
* Switch to a new external colormap between output passes.
*/
GLOBAL void
jpeg_new_colormap( j_decompress_ptr cinfo ) {
my_master_ptr master = (my_master_ptr) cinfo->master;
/* Prevent application from calling me at wrong times */
if ( cinfo->global_state != DSTATE_BUFIMAGE ) {
ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
}
if ( ( cinfo->quantize_colors ) && ( cinfo->enable_external_quant ) &&
( cinfo->colormap != NULL ) ) {
/* Select 2-pass quantizer for external colormap use */
cinfo->cquantize = master->quantizer_2pass;
/* Notify quantizer of colormap change */
( *cinfo->cquantize->new_color_map )( cinfo );
master->pub.is_dummy_pass = FALSE;/* just in case */
} else {
ERREXIT( cinfo, JERR_MODE_CHANGE );
}
}
#endif /* D_MULTISCAN_FILES_SUPPORTED */
/*
* Initialize master decompression control and select active modules.
* This is performed at the start of jpeg_start_decompress.
*/
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_output_pass = prepare_for_output_pass;
master->pub.finish_output_pass = finish_output_pass;
master->pub.is_dummy_pass = FALSE;
master_selection( cinfo );
}