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/*
* jdmainct.h
*
* This file was part of the Independent JPEG Group's software:
* Copyright (C) 1994-1996, Thomas G. Lane.
* For conditions of distribution and use, see the accompanying README.ijg
* file.
*/
#define JPEG_INTERNALS
#include "jpeglib.h"
#include "jpegcomp.h"
/* 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 */
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_ptr = (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_ptr->xbuffer[0][ci];
xbuf1 = main_ptr->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];
}
}
}
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