compiler/libjpeg/main/jdlossls.c

   1 /*
   2     $Id$
   3 */
   4
   5 /*
   6  * jdlossls.c
   7  *
   8  * Copyright (C) 1998, Thomas G. Lane.
   9  * This file is part of the Independent JPEG Group's software.
  10  * For conditions of distribution and use, see the accompanying README file.
  11  *
  12  * This file contains the control logic for the lossless JPEG decompressor.
  13  */
  14
  15 #define JPEG_INTERNALS
  16 #include "jinclude.h"
  17 #include "jpeglib.h"
  18 #include "jlossls.h"
  19
  20
  21 #ifdef D_LOSSLESS_SUPPORTED
  22
  23 /*
  24  * Compute output image dimensions and related values.
  25  */
  26
  27 METHODDEF(void)
  28 calc_output_dimensions (j_decompress_ptr cinfo)
  29 {
  30   /* Hardwire it to "no scaling" */
  31   cinfo->output_width = cinfo->image_width;
  32   cinfo->output_height = cinfo->image_height;
  33   /* jdinput.c has already initialized codec_data_unit to 1,
  34    * and has computed unscaled downsampled_width and downsampled_height.
  35    */
  36 }
  37
  38
  39 /*
  40  * Initialize for an input processing pass.
  41  */
  42
  43 METHODDEF(void)
  44 start_input_pass (j_decompress_ptr cinfo)
  45 {
  46   j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;
  47
  48   (*losslsd->entropy_start_pass) (cinfo);
  49   (*losslsd->predict_start_pass) (cinfo);
  50   (*losslsd->scaler_start_pass) (cinfo);
  51   (*losslsd->diff_start_input_pass) (cinfo);
  52 }
  53
  54
  55 /*
  56  * Initialize the lossless decompression codec.
  57  * This is called only once, during master selection.
  58  */
  59
  60 JGLOBAL(void)
  61 jinit_lossless_d_codec(j_decompress_ptr cinfo)
  62 {
  63   j_lossless_d_ptr losslsd;
  64   boolean use_c_buffer;
  65
  66   /* Create subobject in permanent pool */
  67   losslsd = (j_lossless_d_ptr)
  68     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
  69                                 SIZEOF(jpeg_lossless_d_codec));
  70   cinfo->codec = (struct jpeg_d_codec *) losslsd;
  71
  72   /* Initialize sub-modules */
  73   /* Entropy decoding: either Huffman or arithmetic coding. */
  74   if (cinfo->arith_code) {
  75     ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
  76   } else {
  77     jinit_lhuff_decoder(cinfo);
  78   }
  79
  80   /* Undifferencer */
  81   jinit_undifferencer(cinfo);
  82
  83   /* Scaler */
  84   jinit_d_scaler(cinfo);
  85
  86   use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
  87   jinit_d_diff_controller(cinfo, use_c_buffer);
  88
  89   /* Initialize method pointers.
  90    *
  91    * Note: consume_data, start_output_pass and decompress_data are
  92    * assigned in jddiffct.c.
  93    */
  94   losslsd->pub.calc_output_dimensions = calc_output_dimensions;
  95   losslsd->pub.start_input_pass = start_input_pass;
  96 }
  97
  98 #endif /* D_LOSSLESS_SUPPORTED */