1 /* 2 * jdmainct.h 3 * 4 * This file was part of the Independent JPEG Group's software: 5 * Copyright (C) 1994-1996, Thomas G. Lane. 6 * For conditions of distribution and use, see the accompanying README.ijg 7 * file. 8 */ 9 10 #define JPEG_INTERNALS 11 #include "jpeglib.h" 12 #include "jpegcomp.h" 13 14 15 /* Private buffer controller object */ 16 17 typedef struct { 18 struct jpeg_d_main_controller pub; /* public fields */ 19 20 /* Pointer to allocated workspace (M or M+2 row groups). */ 21 JSAMPARRAY buffer[MAX_COMPONENTS]; 22 23 boolean buffer_full; /* Have we gotten an iMCU row from decoder? */ 24 JDIMENSION rowgroup_ctr; /* counts row groups output to postprocessor */ 25 26 /* Remaining fields are only used in the context case. */ 27 28 /* These are the master pointers to the funny-order pointer lists. */ 29 JSAMPIMAGE xbuffer[2]; /* pointers to weird pointer lists */ 30 31 int whichptr; /* indicates which pointer set is now in use */ 32 int context_state; /* process_data state machine status */ 33 JDIMENSION rowgroups_avail; /* row groups available to postprocessor */ 34 JDIMENSION iMCU_row_ctr; /* counts iMCU rows to detect image top/bot */ 35 } my_main_controller; 36 37 typedef my_main_controller *my_main_ptr; 38 39 40 /* context_state values: */ 41 #define CTX_PREPARE_FOR_IMCU 0 /* need to prepare for MCU row */ 42 #define CTX_PROCESS_IMCU 1 /* feeding iMCU to postprocessor */ 43 #define CTX_POSTPONED_ROW 2 /* feeding postponed row group */ 44 45 46 LOCAL(void) 47 set_wraparound_pointers (j_decompress_ptr cinfo) 48 /* Set up the "wraparound" pointers at top and bottom of the pointer lists. 49 * This changes the pointer list state from top-of-image to the normal state. 50 */ 51 { 52 my_main_ptr main_ptr = (my_main_ptr) cinfo->main; 53 int ci, i, rgroup; 54 int M = cinfo->_min_DCT_scaled_size; 55 jpeg_component_info *compptr; 56 JSAMPARRAY xbuf0, xbuf1; 57 58 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 59 ci++, compptr++) { 60 rgroup = (compptr->v_samp_factor * compptr->_DCT_scaled_size) / 61 cinfo->_min_DCT_scaled_size; /* height of a row group of component */ 62 xbuf0 = main_ptr->xbuffer[0][ci]; 63 xbuf1 = main_ptr->xbuffer[1][ci]; 64 for (i = 0; i < rgroup; i++) { 65 xbuf0[i - rgroup] = xbuf0[rgroup*(M+1) + i]; 66 xbuf1[i - rgroup] = xbuf1[rgroup*(M+1) + i]; 67 xbuf0[rgroup*(M+2) + i] = xbuf0[i]; 68 xbuf1[rgroup*(M+2) + i] = xbuf1[i]; 69 } 70 } 71 } 72
