Line data    Source code

       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           0 : 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           0 :   my_main_ptr main_ptr = (my_main_ptr) cinfo->main;
      53             :   int ci, i, rgroup;
      54           0 :   int M = cinfo->_min_DCT_scaled_size;
      55             :   jpeg_component_info *compptr;
      56             :   JSAMPARRAY xbuf0, xbuf1;
      57             : 
      58           0 :   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
      59           0 :        ci++, compptr++) {
      60           0 :     rgroup = (compptr->v_samp_factor * compptr->_DCT_scaled_size) /
      61           0 :       cinfo->_min_DCT_scaled_size; /* height of a row group of component */
      62           0 :     xbuf0 = main_ptr->xbuffer[0][ci];
      63           0 :     xbuf1 = main_ptr->xbuffer[1][ci];
      64           0 :     for (i = 0; i < rgroup; i++) {
      65           0 :       xbuf0[i - rgroup] = xbuf0[rgroup*(M+1) + i];
      66           0 :       xbuf1[i - rgroup] = xbuf1[rgroup*(M+1) + i];
      67           0 :       xbuf0[rgroup*(M+2) + i] = xbuf0[i];
      68           0 :       xbuf1[rgroup*(M+2) + i] = xbuf1[i];
      69             :     }
      70             :   }
      71           0 : }