#if !defined(_FX_JPEG_TURBO_) | |
/* | |
* jdmainct.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 the main buffer controller for decompression. | |
* The main buffer lies between the JPEG decompressor proper and the | |
* post-processor; it holds downsampled data in the JPEG colorspace. | |
* | |
* Note that this code is bypassed in raw-data mode, since the application | |
* supplies the equivalent of the main buffer in that case. | |
*/ | |
#define JPEG_INTERNALS | |
#include "jinclude.h" | |
#include "jpeglib.h" | |
/* | |
* In the current system design, the main buffer need never be a full-image | |
* buffer; any full-height buffers will be found inside the coefficient or | |
* postprocessing controllers. Nonetheless, the main controller is not | |
* trivial. Its responsibility is to provide context rows for upsampling/ | |
* rescaling, and doing this in an efficient fashion is a bit tricky. | |
* | |
* Postprocessor input data is counted in "row groups". A row group | |
* is defined to be (v_samp_factor * DCT_scaled_size / min_DCT_scaled_size) | |
* sample rows of each component. (We require DCT_scaled_size values to be | |
* chosen such that these numbers are integers. In practice DCT_scaled_size | |
* values will likely be powers of two, so we actually have the stronger | |
* condition that DCT_scaled_size / min_DCT_scaled_size is an integer.) | |
* Upsampling will typically produce max_v_samp_factor pixel rows from each | |
* row group (times any additional scale factor that the upsampler is | |
* applying). | |
* | |
* The coefficient controller will deliver data to us one iMCU row at a time; | |
* each iMCU row contains v_samp_factor * DCT_scaled_size sample rows, or | |
* exactly min_DCT_scaled_size row groups. (This amount of data corresponds | |
* to one row of MCUs when the image is fully interleaved.) Note that the | |
* number of sample rows varies across components, but the number of row | |
* groups does not. Some garbage sample rows may be included in the last iMCU | |
* row at the bottom of the image. | |
* | |
* Depending on the vertical scaling algorithm used, the upsampler may need | |
* access to the sample row(s) above and below its current input row group. | |
* The upsampler is required to set need_context_rows TRUE at global selection | |
* time if so. When need_context_rows is FALSE, this controller can simply | |
* obtain one iMCU row at a time from the coefficient controller and dole it | |
* out as row groups to the postprocessor. | |
* | |
* When need_context_rows is TRUE, this controller guarantees that the buffer | |
* passed to postprocessing contains at least one row group's worth of samples | |
* above and below the row group(s) being processed. Note that the context | |
* rows "above" the first passed row group appear at negative row offsets in | |
* the passed buffer. At the top and bottom of the image, the required | |
* context rows are manufactured by duplicating the first or last real sample | |
* row; this avoids having special cases in the upsampling inner loops. | |
* | |
* The amount of context is fixed at one row group just because that's a | |
* convenient number for this controller to work with. The existing | |
* upsamplers really only need one sample row of context. An upsampler | |
* supporting arbitrary output rescaling might wish for more than one row | |
* group of context when shrinking the image; tough, we don't handle that. | |
* (This is justified by the assumption that downsizing will be handled mostly | |
* by adjusting the DCT_scaled_size values, so that the actual scale factor at | |
* the upsample step needn't be much less than one.) | |
* | |
* To provide the desired context, we have to retain the last two row groups | |
* of one iMCU row while reading in the next iMCU row. (The last row group | |
* can't be processed until we have another row group for its below-context, | |
* and so we have to save the next-to-last group too for its above-context.) | |
* We could do this most simply by copying data around in our buffer, but | |
* that'd be very slow. We can avoid copying any data by creating a rather | |
* strange pointer structure. Here's how it works. We allocate a workspace | |
* consisting of M+2 row groups (where M = min_DCT_scaled_size is the number | |
* of row groups per iMCU row). We create two sets of redundant pointers to | |
* the workspace. Labeling the physical row groups 0 to M+1, the synthesized | |
* pointer lists look like this: | |
* M+1 M-1 | |
* master pointer --> 0 master pointer --> 0 | |
* 1 1 | |
* ... ... | |
* M-3 M-3 | |
* M-2 M | |
* M-1 M+1 | |
* M M-2 | |
* M+1 M-1 | |
* 0 0 | |
* We read alternate iMCU rows using each master pointer; thus the last two | |
* row groups of the previous iMCU row remain un-overwritten in the workspace. | |
* The pointer lists are set up so that the required context rows appear to | |
* be adjacent to the proper places when we pass the pointer lists to the | |
* upsampler. | |
* | |
* The above pictures describe the normal state of the pointer lists. | |
* At top and bottom of the image, we diddle the pointer lists to duplicate | |
* the first or last sample row as necessary (this is cheaper than copying | |
* sample rows around). | |
* | |
* This scheme breaks down if M < 2, ie, min_DCT_scaled_size is 1. In that | |
* situation each iMCU row provides only one row group so the buffering logic | |
* must be different (eg, we must read two iMCU rows before we can emit the | |
* first row group). For now, we simply do not support providing context | |
* rows when min_DCT_scaled_size is 1. That combination seems unlikely to | |
* be worth providing --- if someone wants a 1/8th-size preview, they probably | |
* want it quick and dirty, so a context-free upsampler is sufficient. | |
*/ | |
/* Private buffer controller object */ | |
typedef struct { | |
struct jpeg_d_main_controller pub; /* public fields */ | |
/* Pointer to allocated workspace (M or M+2 row groups). */ | |
JSAMPARRAY buffer[MAX_COMPONENTS]; | |
boolean buffer_full; /* Have we gotten an iMCU row from decoder? */ | |
JDIMENSION rowgroup_ctr; /* counts row groups output to postprocessor */ | |
/* Remaining fields are only used in the context case. */ | |
/* These are the master pointers to the funny-order pointer lists. */ | |
JSAMPIMAGE xbuffer[2]; /* pointers to weird pointer lists */ | |
int whichptr; /* indicates which pointer set is now in use */ | |
int context_state; /* process_data state machine status */ | |
JDIMENSION rowgroups_avail; /* row groups available to postprocessor */ | |
JDIMENSION iMCU_row_ctr; /* counts iMCU rows to detect image top/bot */ | |
} my_main_controller; | |
typedef my_main_controller * my_main_ptr; | |
/* context_state values: */ | |
#define CTX_PREPARE_FOR_IMCU 0 /* need to prepare for MCU row */ | |
#define CTX_PROCESS_IMCU 1 /* feeding iMCU to postprocessor */ | |
#define CTX_POSTPONED_ROW 2 /* feeding postponed row group */ | |
/* Forward declarations */ | |
METHODDEF(void) process_data_simple_main | |
JPP((j_decompress_ptr cinfo, JSAMPARRAY output_buf, | |
JDIMENSION *out_row_ctr, JDIMENSION out_rows_avail)); | |
METHODDEF(void) process_data_context_main | |
JPP((j_decompress_ptr cinfo, JSAMPARRAY output_buf, | |
JDIMENSION *out_row_ctr, JDIMENSION out_rows_avail)); | |
#ifdef QUANT_2PASS_SUPPORTED | |
METHODDEF(void) process_data_crank_post | |
JPP((j_decompress_ptr cinfo, JSAMPARRAY output_buf, | |
JDIMENSION *out_row_ctr, JDIMENSION out_rows_avail)); | |
#endif | |
LOCAL(void) | |
alloc_funny_pointers (j_decompress_ptr cinfo) | |
/* Allocate space for the funny pointer lists. | |
* This is done only once, not once per pass. | |
*/ | |
{ | |
my_main_ptr main = (my_main_ptr) cinfo->main; | |
int ci, rgroup; | |
int M = cinfo->min_DCT_scaled_size; | |
jpeg_component_info *compptr; | |
JSAMPARRAY xbuf; | |
/* Get top-level space for component array pointers. | |
* We alloc both arrays with one call to save a few cycles. | |
*/ | |
main->xbuffer[0] = (JSAMPIMAGE) | |
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
cinfo->num_components * 2 * SIZEOF(JSAMPARRAY)); | |
main->xbuffer[1] = main->xbuffer[0] + cinfo->num_components; | |
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; | |
ci++, compptr++) { | |
rgroup = (compptr->v_samp_factor * compptr->DCT_scaled_size) / | |
cinfo->min_DCT_scaled_size; /* height of a row group of component */ | |
/* Get space for pointer lists --- M+4 row groups in each list. | |
* We alloc both pointer lists with one call to save a few cycles. | |
*/ | |
xbuf = (JSAMPARRAY) | |
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
2 * (rgroup * (M + 4)) * SIZEOF(JSAMPROW)); | |
xbuf += rgroup; /* want one row group at negative offsets */ | |
main->xbuffer[0][ci] = xbuf; | |
xbuf += rgroup * (M + 4); | |
main->xbuffer[1][ci] = xbuf; | |
} | |
} | |
LOCAL(void) | |
make_funny_pointers (j_decompress_ptr cinfo) | |
/* Create the funny pointer lists discussed in the comments above. | |
* The actual workspace is already allocated (in main->buffer), | |
* and the space for the pointer lists is allocated too. | |
* This routine just fills in the curiously ordered lists. | |
* This will be repeated at the beginning of each pass. | |
*/ | |
{ | |
my_main_ptr main = (my_main_ptr) cinfo->main; | |
int ci, i, rgroup; | |
int M = cinfo->min_DCT_scaled_size; | |
jpeg_component_info *compptr; | |
JSAMPARRAY buf, xbuf0, xbuf1; | |
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; | |
ci++, compptr++) { | |
rgroup = (compptr->v_samp_factor * compptr->DCT_scaled_size) / | |
cinfo->min_DCT_scaled_size; /* height of a row group of component */ | |
xbuf0 = main->xbuffer[0][ci]; | |
xbuf1 = main->xbuffer[1][ci]; | |
/* First copy the workspace pointers as-is */ | |
buf = main->buffer[ci]; | |
for (i = 0; i < rgroup * (M + 2); i++) { | |
xbuf0[i] = xbuf1[i] = buf[i]; | |
} | |
/* In the second list, put the last four row groups in swapped order */ | |
for (i = 0; i < rgroup * 2; i++) { | |
xbuf1[rgroup*(M-2) + i] = buf[rgroup*M + i]; | |
xbuf1[rgroup*M + i] = buf[rgroup*(M-2) + i]; | |
} | |
/* The wraparound pointers at top and bottom will be filled later | |
* (see set_wraparound_pointers, below). Initially we want the "above" | |
* pointers to duplicate the first actual data line. This only needs | |
* to happen in xbuffer[0]. | |
*/ | |
for (i = 0; i < rgroup; i++) { | |
xbuf0[i - rgroup] = xbuf0[0]; | |
} | |
} | |
} | |
LOCAL(void) | |
set_wraparound_pointers (j_decompress_ptr cinfo) | |
/* Set up the "wraparound" pointers at top and bottom of the pointer lists. | |
* This changes the pointer list state from top-of-image to the normal state. | |
*/ | |
{ | |
my_main_ptr main = (my_main_ptr) cinfo->main; | |
int ci, i, rgroup; | |
int M = cinfo->min_DCT_scaled_size; | |
jpeg_component_info *compptr; | |
JSAMPARRAY xbuf0, xbuf1; | |
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; | |
ci++, compptr++) { | |
rgroup = (compptr->v_samp_factor * compptr->DCT_scaled_size) / | |
cinfo->min_DCT_scaled_size; /* height of a row group of component */ | |
xbuf0 = main->xbuffer[0][ci]; | |
xbuf1 = main->xbuffer[1][ci]; | |
for (i = 0; i < rgroup; i++) { | |
xbuf0[i - rgroup] = xbuf0[rgroup*(M+1) + i]; | |
xbuf1[i - rgroup] = xbuf1[rgroup*(M+1) + i]; | |
xbuf0[rgroup*(M+2) + i] = xbuf0[i]; | |
xbuf1[rgroup*(M+2) + i] = xbuf1[i]; | |
} | |
} | |
} | |
LOCAL(void) | |
set_bottom_pointers (j_decompress_ptr cinfo) | |
/* Change the pointer lists to duplicate the last sample row at the bottom | |
* of the image. whichptr indicates which xbuffer holds the final iMCU row. | |
* Also sets rowgroups_avail to indicate number of nondummy row groups in row. | |
*/ | |
{ | |
my_main_ptr main = (my_main_ptr) cinfo->main; | |
int ci, i, rgroup, iMCUheight, rows_left; | |
jpeg_component_info *compptr; | |
JSAMPARRAY xbuf; | |
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; | |
ci++, compptr++) { | |
/* Count sample rows in one iMCU row and in one row group */ | |
iMCUheight = compptr->v_samp_factor * compptr->DCT_scaled_size; | |
rgroup = iMCUheight / cinfo->min_DCT_scaled_size; | |
/* Count nondummy sample rows remaining for this component */ | |
rows_left = (int) (compptr->downsampled_height % (JDIMENSION) iMCUheight); | |
if (rows_left == 0) rows_left = iMCUheight; | |
/* Count nondummy row groups. Should get same answer for each component, | |
* so we need only do it once. | |
*/ | |
if (ci == 0) { | |
main->rowgroups_avail = (JDIMENSION) ((rows_left-1) / rgroup + 1); | |
} | |
/* Duplicate the last real sample row rgroup*2 times; this pads out the | |
* last partial rowgroup and ensures at least one full rowgroup of context. | |
*/ | |
xbuf = main->xbuffer[main->whichptr][ci]; | |
for (i = 0; i < rgroup * 2; i++) { | |
xbuf[rows_left + i] = xbuf[rows_left-1]; | |
} | |
} | |
} | |
/* | |
* Initialize for a processing pass. | |
*/ | |
METHODDEF(void) | |
start_pass_main (j_decompress_ptr cinfo, J_BUF_MODE pass_mode) | |
{ | |
my_main_ptr main = (my_main_ptr) cinfo->main; | |
switch (pass_mode) { | |
case JBUF_PASS_THRU: | |
if (cinfo->upsample->need_context_rows) { | |
main->pub.process_data = process_data_context_main; | |
make_funny_pointers(cinfo); /* Create the xbuffer[] lists */ | |
main->whichptr = 0; /* Read first iMCU row into xbuffer[0] */ | |
main->context_state = CTX_PREPARE_FOR_IMCU; | |
main->iMCU_row_ctr = 0; | |
} else { | |
/* Simple case with no context needed */ | |
main->pub.process_data = process_data_simple_main; | |
} | |
main->buffer_full = FALSE; /* Mark buffer empty */ | |
main->rowgroup_ctr = 0; | |
break; | |
#ifdef QUANT_2PASS_SUPPORTED | |
case JBUF_CRANK_DEST: | |
/* For last pass of 2-pass quantization, just crank the postprocessor */ | |
main->pub.process_data = process_data_crank_post; | |
break; | |
#endif | |
default: | |
ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); | |
break; | |
} | |
} | |
/* | |
* Process some data. | |
* This handles the simple case where no context is required. | |
*/ | |
METHODDEF(void) | |
process_data_simple_main (j_decompress_ptr cinfo, | |
JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, | |
JDIMENSION out_rows_avail) | |
{ | |
my_main_ptr main = (my_main_ptr) cinfo->main; | |
JDIMENSION rowgroups_avail; | |
/* Read input data if we haven't filled the main buffer yet */ | |
if (! main->buffer_full) { | |
if (! (*cinfo->coef->decompress_data) (cinfo, main->buffer)) | |
return; /* suspension forced, can do nothing more */ | |
main->buffer_full = TRUE; /* OK, we have an iMCU row to work with */ | |
} | |
/* There are always min_DCT_scaled_size row groups in an iMCU row. */ | |
rowgroups_avail = (JDIMENSION) cinfo->min_DCT_scaled_size; | |
/* Note: at the bottom of the image, we may pass extra garbage row groups | |
* to the postprocessor. The postprocessor has to check for bottom | |
* of image anyway (at row resolution), so no point in us doing it too. | |
*/ | |
/* Feed the postprocessor */ | |
(*cinfo->post->post_process_data) (cinfo, main->buffer, | |
&main->rowgroup_ctr, rowgroups_avail, | |
output_buf, out_row_ctr, out_rows_avail); | |
/* Has postprocessor consumed all the data yet? If so, mark buffer empty */ | |
if (main->rowgroup_ctr >= rowgroups_avail) { | |
main->buffer_full = FALSE; | |
main->rowgroup_ctr = 0; | |
} | |
} | |
/* | |
* Process some data. | |
* This handles the case where context rows must be provided. | |
*/ | |
METHODDEF(void) | |
process_data_context_main (j_decompress_ptr cinfo, | |
JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, | |
JDIMENSION out_rows_avail) | |
{ | |
my_main_ptr main = (my_main_ptr) cinfo->main; | |
/* Read input data if we haven't filled the main buffer yet */ | |
if (! main->buffer_full) { | |
if (! (*cinfo->coef->decompress_data) (cinfo, | |
main->xbuffer[main->whichptr])) | |
return; /* suspension forced, can do nothing more */ | |
main->buffer_full = TRUE; /* OK, we have an iMCU row to work with */ | |
main->iMCU_row_ctr++; /* count rows received */ | |
} | |
/* Postprocessor typically will not swallow all the input data it is handed | |
* in one call (due to filling the output buffer first). Must be prepared | |
* to exit and restart. This switch lets us keep track of how far we got. | |
* Note that each case falls through to the next on successful completion. | |
*/ | |
switch (main->context_state) { | |
case CTX_POSTPONED_ROW: | |
/* Call postprocessor using previously set pointers for postponed row */ | |
(*cinfo->post->post_process_data) (cinfo, main->xbuffer[main->whichptr], | |
&main->rowgroup_ctr, main->rowgroups_avail, | |
output_buf, out_row_ctr, out_rows_avail); | |
if (main->rowgroup_ctr < main->rowgroups_avail) | |
return; /* Need to suspend */ | |
main->context_state = CTX_PREPARE_FOR_IMCU; | |
if (*out_row_ctr >= out_rows_avail) | |
return; /* Postprocessor exactly filled output buf */ | |
/*FALLTHROUGH*/ | |
case CTX_PREPARE_FOR_IMCU: | |
/* Prepare to process first M-1 row groups of this iMCU row */ | |
main->rowgroup_ctr = 0; | |
main->rowgroups_avail = (JDIMENSION) (cinfo->min_DCT_scaled_size - 1); | |
/* Check for bottom of image: if so, tweak pointers to "duplicate" | |
* the last sample row, and adjust rowgroups_avail to ignore padding rows. | |
*/ | |
if (main->iMCU_row_ctr == cinfo->total_iMCU_rows) | |
set_bottom_pointers(cinfo); | |
main->context_state = CTX_PROCESS_IMCU; | |
/*FALLTHROUGH*/ | |
case CTX_PROCESS_IMCU: | |
/* Call postprocessor using previously set pointers */ | |
(*cinfo->post->post_process_data) (cinfo, main->xbuffer[main->whichptr], | |
&main->rowgroup_ctr, main->rowgroups_avail, | |
output_buf, out_row_ctr, out_rows_avail); | |
if (main->rowgroup_ctr < main->rowgroups_avail) | |
return; /* Need to suspend */ | |
/* After the first iMCU, change wraparound pointers to normal state */ | |
if (main->iMCU_row_ctr == 1) | |
set_wraparound_pointers(cinfo); | |
/* Prepare to load new iMCU row using other xbuffer list */ | |
main->whichptr ^= 1; /* 0=>1 or 1=>0 */ | |
main->buffer_full = FALSE; | |
/* Still need to process last row group of this iMCU row, */ | |
/* which is saved at index M+1 of the other xbuffer */ | |
main->rowgroup_ctr = (JDIMENSION) (cinfo->min_DCT_scaled_size + 1); | |
main->rowgroups_avail = (JDIMENSION) (cinfo->min_DCT_scaled_size + 2); | |
main->context_state = CTX_POSTPONED_ROW; | |
} | |
} | |
/* | |
* Process some data. | |
* Final pass of two-pass quantization: just call the postprocessor. | |
* Source data will be the postprocessor controller's internal buffer. | |
*/ | |
#ifdef QUANT_2PASS_SUPPORTED | |
METHODDEF(void) | |
process_data_crank_post (j_decompress_ptr cinfo, | |
JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, | |
JDIMENSION out_rows_avail) | |
{ | |
(*cinfo->post->post_process_data) (cinfo, (JSAMPIMAGE) NULL, | |
(JDIMENSION *) NULL, (JDIMENSION) 0, | |
output_buf, out_row_ctr, out_rows_avail); | |
} | |
#endif /* QUANT_2PASS_SUPPORTED */ | |
/* | |
* Initialize main buffer controller. | |
*/ | |
GLOBAL(void) | |
jinit_d_main_controller (j_decompress_ptr cinfo, boolean need_full_buffer) | |
{ | |
my_main_ptr main; | |
int ci, rgroup, ngroups; | |
jpeg_component_info *compptr; | |
main = (my_main_ptr) | |
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
SIZEOF(my_main_controller)); | |
cinfo->main = (struct jpeg_d_main_controller *) main; | |
main->pub.start_pass = start_pass_main; | |
if (need_full_buffer) /* shouldn't happen */ | |
ERREXIT(cinfo, JERR_BAD_BUFFER_MODE); | |
/* Allocate the workspace. | |
* ngroups is the number of row groups we need. | |
*/ | |
if (cinfo->upsample->need_context_rows) { | |
if (cinfo->min_DCT_scaled_size < 2) /* unsupported, see comments above */ | |
ERREXIT(cinfo, JERR_NOTIMPL); | |
alloc_funny_pointers(cinfo); /* Alloc space for xbuffer[] lists */ | |
ngroups = cinfo->min_DCT_scaled_size + 2; | |
} else { | |
ngroups = cinfo->min_DCT_scaled_size; | |
} | |
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; | |
ci++, compptr++) { | |
rgroup = (compptr->v_samp_factor * compptr->DCT_scaled_size) / | |
cinfo->min_DCT_scaled_size; /* height of a row group of component */ | |
main->buffer[ci] = (*cinfo->mem->alloc_sarray) | |
((j_common_ptr) cinfo, JPOOL_IMAGE, | |
compptr->width_in_blocks * compptr->DCT_scaled_size, | |
(JDIMENSION) (rgroup * ngroups)); | |
} | |
} | |
#endif //_FX_JPEG_TURBO_ |