/*

* jdmaster.c

*

* Copyright (C) 1991-1997, Thomas G. Lane.

* Modified 2002-2011 by Guido Vollbeding.

* 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_h_scaled_size != cinfo->min_DCT_h_scaled_size ||

cinfo->comp_info[1].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size ||

cinfo->comp_info[2].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size ||

cinfo->comp_info[0].DCT_v_scaled_size != cinfo->min_DCT_v_scaled_size ||

cinfo->comp_info[1].DCT_v_scaled_size != cinfo->min_DCT_v_scaled_size ||

cinfo->comp_info[2].DCT_v_scaled_size != cinfo->min_DCT_v_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.

* This function is used for full decompression.

*/

{

#ifdef IDCT_SCALING_SUPPORTED

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);

/* Compute core output image dimensions and DCT scaling choices. */

jpeg_core_output_dimensions(cinfo);

#ifdef IDCT_SCALING_SUPPORTED

/* 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 adapts subsampling ratios which are powers of 2.

*/

for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;

ci++, compptr++) {

int ssize = 1;

while (cinfo->min_DCT_h_scaled_size * ssize <=

(cinfo->do_fancy_upsampling ? DCTSIZE : DCTSIZE / 2) &&

(cinfo->max_h_samp_factor % (compptr->h_samp_factor * ssize * 2)) == 0) {

ssize = ssize * 2;

}

compptr->DCT_h_scaled_size = cinfo->min_DCT_h_scaled_size * ssize;

ssize = 1;

while (cinfo->min_DCT_v_scaled_size * ssize <=

(cinfo->do_fancy_upsampling ? DCTSIZE : DCTSIZE / 2) &&

(cinfo->max_v_samp_factor % (compptr->v_samp_factor * ssize * 2)) == 0) {

ssize = ssize * 2;

}

compptr->DCT_v_scaled_size = cinfo->min_DCT_v_scaled_size * ssize;

/* We don't support IDCT ratios larger than 2. */

if (compptr->DCT_h_scaled_size > compptr->DCT_v_scaled_size * 2)

compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size * 2;

else if (compptr->DCT_v_scaled_size > compptr->DCT_h_scaled_size * 2)

compptr->DCT_v_scaled_size = compptr->DCT_h_scaled_size * 2;

}

/* 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_h_scaled_size),

(long) (cinfo->max_h_samp_factor * cinfo->block_size));

compptr->downsampled_height = (JDIMENSION)

jdiv_round_up((long) cinfo->image_height *

(long) (compptr->v_samp_factor * compptr->DCT_v_scaled_size),

(long) (cinfo->max_v_samp_factor * cinfo->block_size));

}

#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:

cinfo->out_color_components = RGB_PIXELSIZE;

break;

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)

jinit_arith_decoder(cinfo);

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, jdapistd.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);

}