ref: 13ca2581f9f18d441ce911e42c2bd93e387cee4d
dir: /libs/jpeg6/jdinput.cpp/
/*
* jdinput.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 input control logic for the JPEG decompressor.
* These routines are concerned with controlling the decompressor's input
* processing (marker reading and coefficient decoding). The actual input
* reading is done in jdmarker.c, jdhuff.c, and jdphuff.c.
*/
#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
/* Private state */
typedef struct {
struct jpeg_input_controller pub; /* public fields */
boolean inheaders; /* TRUE until first SOS is reached */
} my_input_controller;
typedef my_input_controller * my_inputctl_ptr;
/* Forward declarations */
METHODDEF int consume_markers JPP((j_decompress_ptr cinfo));
/*
* Routines to calculate various quantities related to the size of the image.
*/
LOCAL void
initial_setup (j_decompress_ptr cinfo)
/* Called once, when first SOS marker is reached */
{
int ci;
jpeg_component_info *compptr;
/* Make sure image isn't bigger than I can handle */
if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION ||
(long) cinfo->image_width > (long) JPEG_MAX_DIMENSION)
ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
/* For now, precision must match compiled-in value... */
if (cinfo->data_precision != BITS_IN_JSAMPLE)
ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
/* Check that number of components won't exceed internal array sizes */
if (cinfo->num_components > MAX_COMPONENTS)
ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
MAX_COMPONENTS);
/* 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);
}
/* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE.
* In the full decompressor, this will be overridden by jdmaster.c;
* but in the transcoder, jdmaster.c is not used, so we must do it here.
*/
cinfo->min_DCT_scaled_size = DCTSIZE;
/* Compute dimensions of components */
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
ci++, compptr++) {
compptr->DCT_scaled_size = DCTSIZE;
/* 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));
/* downsampled_width and downsampled_height will also be overridden by
* jdmaster.c if we are doing full decompression. The transcoder library
* doesn't use these values, but the calling application might.
*/
/* Size in samples */
compptr->downsampled_width = (JDIMENSION)
jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
(long) cinfo->max_h_samp_factor);
compptr->downsampled_height = (JDIMENSION)
jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
(long) cinfo->max_v_samp_factor);
/* Mark component needed, until color conversion says otherwise */
compptr->component_needed = TRUE;
/* Mark no quantization table yet saved for component */
compptr->quant_table = NULL;
}
/* Compute number of fully interleaved MCU rows. */
cinfo->total_iMCU_rows = (JDIMENSION)
jdiv_round_up((long) cinfo->image_height,
(long) (cinfo->max_v_samp_factor*DCTSIZE));
/* Decide whether file contains multiple scans */
if (cinfo->comps_in_scan < cinfo->num_components || cinfo->progressive_mode)
cinfo->inputctl->has_multiple_scans = TRUE;
else
cinfo->inputctl->has_multiple_scans = FALSE;
}
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;
/* For noninterleaved scans, it is convenient to define last_row_height
* as the number of block rows present in the last iMCU row.
*/
tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
if (tmp == 0) tmp = compptr->v_samp_factor;
compptr->last_row_height = tmp;
/* 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 > D_MAX_BLOCKS_IN_MCU)
ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
while (mcublks-- > 0) {
cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
}
}
}
}
/*
* Save away a copy of the Q-table referenced by each component present
* in the current scan, unless already saved during a prior scan.
*
* In a multiple-scan JPEG file, the encoder could assign different components
* the same Q-table slot number, but change table definitions between scans
* so that each component uses a different Q-table. (The IJG encoder is not
* currently capable of doing this, but other encoders might.) Since we want
* to be able to dequantize all the components at the end of the file, this
* means that we have to save away the table actually used for each component.
* We do this by copying the table at the start of the first scan containing
* the component.
* The JPEG spec prohibits the encoder from changing the contents of a Q-table
* slot between scans of a component using that slot. If the encoder does so
* anyway, this decoder will simply use the Q-table values that were current
* at the start of the first scan for the component.
*
* The decompressor output side looks only at the saved quant tables,
* not at the current Q-table slots.
*/
LOCAL void
latch_quant_tables (j_decompress_ptr cinfo)
{
int ci, qtblno;
jpeg_component_info *compptr;
JQUANT_TBL * qtbl;
for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
compptr = cinfo->cur_comp_info[ci];
/* No work if we already saved Q-table for this component */
if (compptr->quant_table != NULL)
continue;
/* Make sure specified quantization table is present */
qtblno = compptr->quant_tbl_no;
if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS ||
cinfo->quant_tbl_ptrs[qtblno] == NULL)
ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno);
/* OK, save away the quantization table */
qtbl = (JQUANT_TBL *)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
SIZEOF(JQUANT_TBL));
MEMCOPY(qtbl, cinfo->quant_tbl_ptrs[qtblno], SIZEOF(JQUANT_TBL));
compptr->quant_table = qtbl;
}
}
/*
* Initialize the input modules to read a scan of compressed data.
* The first call to this is done by jdmaster.c after initializing
* the entire decompressor (during jpeg_start_decompress).
* Subsequent calls come from consume_markers, below.
*/
METHODDEF void
start_input_pass (j_decompress_ptr cinfo)
{
per_scan_setup(cinfo);
latch_quant_tables(cinfo);
(*cinfo->entropy->start_pass) (cinfo);
(*cinfo->coef->start_input_pass) (cinfo);
cinfo->inputctl->consume_input = cinfo->coef->consume_data;
}
/*
* Finish up after inputting a compressed-data scan.
* This is called by the coefficient controller after it's read all
* the expected data of the scan.
*/
METHODDEF void
finish_input_pass (j_decompress_ptr cinfo)
{
cinfo->inputctl->consume_input = consume_markers;
}
/*
* Read JPEG markers before, between, or after compressed-data scans.
* Change state as necessary when a new scan is reached.
* Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.
*
* The consume_input method pointer points either here or to the
* coefficient controller's consume_data routine, depending on whether
* we are reading a compressed data segment or inter-segment markers.
*/
METHODDEF int
consume_markers (j_decompress_ptr cinfo)
{
my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
int val;
if (inputctl->pub.eoi_reached) /* After hitting EOI, read no further */
return JPEG_REACHED_EOI;
val = (*cinfo->marker->read_markers) (cinfo);
switch (val) {
case JPEG_REACHED_SOS: /* Found SOS */
if (inputctl->inheaders) { /* 1st SOS */
initial_setup(cinfo);
inputctl->inheaders = FALSE;
/* Note: start_input_pass must be called by jdmaster.c
* before any more input can be consumed. jdapi.c is
* responsible for enforcing this sequencing.
*/
} else { /* 2nd or later SOS marker */
if (! inputctl->pub.has_multiple_scans)
ERREXIT(cinfo, JERR_EOI_EXPECTED); /* Oops, I wasn't expecting this! */
start_input_pass(cinfo);
}
break;
case JPEG_REACHED_EOI: /* Found EOI */
inputctl->pub.eoi_reached = TRUE;
if (inputctl->inheaders) { /* Tables-only datastream, apparently */
if (cinfo->marker->saw_SOF)
ERREXIT(cinfo, JERR_SOF_NO_SOS);
} else {
/* Prevent infinite loop in coef ctlr's decompress_data routine
* if user set output_scan_number larger than number of scans.
*/
if (cinfo->output_scan_number > cinfo->input_scan_number)
cinfo->output_scan_number = cinfo->input_scan_number;
}
break;
case JPEG_SUSPENDED:
break;
}
return val;
}
/*
* Reset state to begin a fresh datastream.
*/
METHODDEF void
reset_input_controller (j_decompress_ptr cinfo)
{
my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
inputctl->pub.consume_input = consume_markers;
inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
inputctl->pub.eoi_reached = FALSE;
inputctl->inheaders = TRUE;
/* Reset other modules */
(*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
(*cinfo->marker->reset_marker_reader) (cinfo);
/* Reset progression state -- would be cleaner if entropy decoder did this */
cinfo->coef_bits = NULL;
}
/*
* Initialize the input controller module.
* This is called only once, when the decompression object is created.
*/
GLOBAL void
jinit_input_controller (j_decompress_ptr cinfo)
{
my_inputctl_ptr inputctl;
/* Create subobject in permanent pool */
inputctl = (my_inputctl_ptr)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
SIZEOF(my_input_controller));
cinfo->inputctl = (struct jpeg_input_controller *) inputctl;
/* Initialize method pointers */
inputctl->pub.consume_input = consume_markers;
inputctl->pub.reset_input_controller = reset_input_controller;
inputctl->pub.start_input_pass = start_input_pass;
inputctl->pub.finish_input_pass = finish_input_pass;
/* Initialize state: can't use reset_input_controller since we don't
* want to try to reset other modules yet.
*/
inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
inputctl->pub.eoi_reached = FALSE;
inputctl->inheaders = TRUE;
}