72 lines
2.4 KiB
C
72 lines
2.4 KiB
C
/*
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* jdmainct.h
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*
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* This file was part of the Independent JPEG Group's software:
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* Copyright (C) 1994-1996, Thomas G. Lane.
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* For conditions of distribution and use, see the accompanying README.ijg
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* file.
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*/
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#define JPEG_INTERNALS
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#include "jpeglib.h"
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#include "jpegcomp.h"
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/* Private buffer controller object */
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typedef struct {
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struct jpeg_d_main_controller pub; /* public fields */
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/* Pointer to allocated workspace (M or M+2 row groups). */
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JSAMPARRAY buffer[MAX_COMPONENTS];
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boolean buffer_full; /* Have we gotten an iMCU row from decoder? */
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JDIMENSION rowgroup_ctr; /* counts row groups output to postprocessor */
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/* Remaining fields are only used in the context case. */
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/* These are the master pointers to the funny-order pointer lists. */
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JSAMPIMAGE xbuffer[2]; /* pointers to weird pointer lists */
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int whichptr; /* indicates which pointer set is now in use */
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int context_state; /* process_data state machine status */
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JDIMENSION rowgroups_avail; /* row groups available to postprocessor */
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JDIMENSION iMCU_row_ctr; /* counts iMCU rows to detect image top/bot */
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} my_main_controller;
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typedef my_main_controller *my_main_ptr;
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/* context_state values: */
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#define CTX_PREPARE_FOR_IMCU 0 /* need to prepare for MCU row */
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#define CTX_PROCESS_IMCU 1 /* feeding iMCU to postprocessor */
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#define CTX_POSTPONED_ROW 2 /* feeding postponed row group */
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LOCAL(void)
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set_wraparound_pointers(j_decompress_ptr cinfo)
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/* Set up the "wraparound" pointers at top and bottom of the pointer lists.
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* This changes the pointer list state from top-of-image to the normal state.
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*/
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{
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my_main_ptr main_ptr = (my_main_ptr)cinfo->main;
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int ci, i, rgroup;
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int M = cinfo->_min_DCT_scaled_size;
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jpeg_component_info *compptr;
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JSAMPARRAY xbuf0, xbuf1;
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for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
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ci++, compptr++) {
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rgroup = (compptr->v_samp_factor * compptr->_DCT_scaled_size) /
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cinfo->_min_DCT_scaled_size; /* height of a row group of component */
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xbuf0 = main_ptr->xbuffer[0][ci];
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xbuf1 = main_ptr->xbuffer[1][ci];
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for (i = 0; i < rgroup; i++) {
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xbuf0[i - rgroup] = xbuf0[rgroup * (M + 1) + i];
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xbuf1[i - rgroup] = xbuf1[rgroup * (M + 1) + i];
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xbuf0[rgroup * (M + 2) + i] = xbuf0[i];
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xbuf1[rgroup * (M + 2) + i] = xbuf1[i];
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}
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}
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}
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