jpeg/jdmaster.c

   1 /*
   2  * jdmaster.c
   3  *
   4  * Copyright (C) 1991-1997, Thomas G. Lane.
   5  * This file is part of the Independent JPEG Group's software.
   6  * For conditions of distribution and use, see the accompanying README file.
   7  *
   8  * This file contains master control logic for the JPEG decompressor.
   9  * These routines are concerned with selecting the modules to be executed
  10  * and with determining the number of passes and the work to be done in each
  11  * pass.
  12  */
  13
  14 #define JPEG_INTERNALS
  15 #include "jinclude.h"
  16 #include "jpeglib.h"
  17
  18 /* Use static array */
  19
  20 const JSAMPLE static_range_table[ (5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE) ]={
  21  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  22  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  23  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  24  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  25  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  26  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  27  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  28  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  29  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  30  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  31  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  32  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  33  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  34  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  35  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  36  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  37  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  38  0x00, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d,
  39  0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c,
  40  0x1d, 0x1e, 0x1f, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b,
  41  0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a,
  42  0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
  43  0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58,
  44  0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
  45  0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76,
  46  0x77, 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85,
  47  0x86, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, 0x90, 0x91, 0x92, 0x93, 0x94,
  48  0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f, 0xa0, 0xa1, 0xa2, 0xa3,
  49  0xa4, 0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf, 0xb0, 0xb1, 0xb2,
  50  0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf, 0xc0, 0xc1,
  51  0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf, 0xd0,
  52  0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
  53  0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee,
  54  0xef, 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd,
  55  0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  56  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  57  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  58  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  59  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  60  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  61  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  62  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  63  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  64  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  65  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  66  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  67  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  68  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  69  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  70  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  71  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  72  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  73  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  74  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  75  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  76  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  77  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  78  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  79  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  80  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00,
  81  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  82  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  83  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  84  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  85  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  86  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  87  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  88  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  89  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  90  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  91  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  92  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  93  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  94  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  95  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  96  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  97  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  98  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  99  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 100  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 101  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 102  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 103  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 104  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 105  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 106  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09,
 107  0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18,
 108  0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
 109  0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36,
 110  0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45,
 111  0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 0x50, 0x51, 0x52, 0x53, 0x54,
 112  0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, 0x60, 0x61, 0x62, 0x63,
 113  0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72,
 114  0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f
 115 };
 116
 117 /* Private state */
 118
 119 typedef struct {
 120   struct jpeg_decomp_master pub; /* public fields */
 121
 122   int pass_number;              /* # of passes completed */
 123
 124   boolean using_merged_upsample; /* TRUE if using merged upsample/cconvert */
 125
 126   /* Saved references to initialized quantizer modules,
 127    * in case we need to switch modes.
 128    */
 129   struct jpeg_color_quantizer * quantizer_1pass;
 130   struct jpeg_color_quantizer * quantizer_2pass;
 131 } my_decomp_master;
 132
 133 typedef my_decomp_master * my_master_ptr;
 134
 135
 136 /*
 137  * Determine whether merged upsample/color conversion should be used.
 138  * CRUCIAL: this must match the actual capabilities of jdmerge.c!
 139  */
 140
 141 LOCAL(boolean)
 142 use_merged_upsample (j_decompress_ptr cinfo)
 143 {
 144 #ifdef UPSAMPLE_MERGING_SUPPORTED
 145   /* Merging is the equivalent of plain box-filter upsampling */
 146   if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling)
 147     return FALSE;
 148   /* jdmerge.c only supports YCC=>RGB color conversion */
 149   if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
 150       cinfo->out_color_space != JCS_RGB ||
 151       cinfo->out_color_components != RGB_PIXELSIZE)
 152     return FALSE;
 153   /* and it only handles 2h1v or 2h2v sampling ratios */
 154   if (cinfo->comp_info[0].h_samp_factor != 2 ||
 155       cinfo->comp_info[1].h_samp_factor != 1 ||
 156       cinfo->comp_info[2].h_samp_factor != 1 ||
 157       cinfo->comp_info[0].v_samp_factor >  2 ||
 158       cinfo->comp_info[1].v_samp_factor != 1 ||
 159       cinfo->comp_info[2].v_samp_factor != 1)
 160     return FALSE;
 161   /* furthermore, it doesn't work if we've scaled the IDCTs differently */
 162   if (cinfo->comp_info[0].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
 163       cinfo->comp_info[1].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
 164       cinfo->comp_info[2].DCT_scaled_size != cinfo->min_DCT_scaled_size)
 165     return FALSE;
 166   /* ??? also need to test for upsample-time rescaling, when & if supported */
 167   return TRUE;                  /* by golly, it'll work... */
 168 #else
 169   return FALSE;
 170 #endif
 171 }
 172
 173
 174 /*
 175  * Compute output image dimensions and related values.
 176  * NOTE: this is exported for possible use by application.
 177  * Hence it mustn't do anything that can't be done twice.
 178  * Also note that it may be called before the master module is initialized!
 179  */
 180
 181 GLOBAL(void)
 182 jpeg_calc_output_dimensions (j_decompress_ptr cinfo)
 183 /* Do computations that are needed before master selection phase */
 184 {
 185 #ifdef IDCT_SCALING_SUPPORTED
 186   int ci;
 187   jpeg_component_info *compptr;
 188 #endif
 189
 190   /* Prevent application from calling me at wrong times */
 191   if (cinfo->global_state != DSTATE_READY)
 192     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
 193
 194 #ifdef IDCT_SCALING_SUPPORTED
 195
 196   /* Compute actual output image dimensions and DCT scaling choices. */
 197   if (cinfo->scale_num * 8 <= cinfo->scale_denom) {
 198     /* Provide 1/8 scaling */
 199     cinfo->output_width = (JDIMENSION)
 200       jdiv_round_up((long) cinfo->image_width, 8L);
 201     cinfo->output_height = (JDIMENSION)
 202       jdiv_round_up((long) cinfo->image_height, 8L);
 203     cinfo->min_DCT_scaled_size = 1;
 204   } else if (cinfo->scale_num * 4 <= cinfo->scale_denom) {
 205     /* Provide 1/4 scaling */
 206     cinfo->output_width = (JDIMENSION)
 207       jdiv_round_up((long) cinfo->image_width, 4L);
 208     cinfo->output_height = (JDIMENSION)
 209       jdiv_round_up((long) cinfo->image_height, 4L);
 210     cinfo->min_DCT_scaled_size = 2;
 211   } else if (cinfo->scale_num * 2 <= cinfo->scale_denom) {
 212     /* Provide 1/2 scaling */
 213     cinfo->output_width = (JDIMENSION)
 214       jdiv_round_up((long) cinfo->image_width, 2L);
 215     cinfo->output_height = (JDIMENSION)
 216       jdiv_round_up((long) cinfo->image_height, 2L);
 217     cinfo->min_DCT_scaled_size = 4;
 218   } else {
 219     /* Provide 1/1 scaling */
 220     cinfo->output_width = cinfo->image_width;
 221     cinfo->output_height = cinfo->image_height;
 222     cinfo->min_DCT_scaled_size = DCTSIZE;
 223   }
 224   /* In selecting the actual DCT scaling for each component, we try to
 225    * scale up the chroma components via IDCT scaling rather than upsampling.
 226    * This saves time if the upsampler gets to use 1:1 scaling.
 227    * Note this code assumes that the supported DCT scalings are powers of 2.
 228    */
 229   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 230        ci++, compptr++) {
 231     int ssize = cinfo->min_DCT_scaled_size;
 232     while (ssize < DCTSIZE &&
 233            (compptr->h_samp_factor * ssize * 2 <=
 234             cinfo->max_h_samp_factor * cinfo->min_DCT_scaled_size) &&
 235            (compptr->v_samp_factor * ssize * 2 <=
 236             cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size)) {
 237       ssize = ssize * 2;
 238     }
 239     compptr->DCT_scaled_size = ssize;
 240   }
 241
 242   /* Recompute downsampled dimensions of components;
 243    * application needs to know these if using raw downsampled data.
 244    */
 245   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
 246        ci++, compptr++) {
 247     /* Size in samples, after IDCT scaling */
 248     compptr->downsampled_width = (JDIMENSION)
 249       jdiv_round_up((long) cinfo->image_width *
 250                     (long) (compptr->h_samp_factor * compptr->DCT_scaled_size),
 251                     (long) (cinfo->max_h_samp_factor * DCTSIZE));
 252     compptr->downsampled_height = (JDIMENSION)
 253       jdiv_round_up((long) cinfo->image_height *
 254                     (long) (compptr->v_samp_factor * compptr->DCT_scaled_size),
 255                     (long) (cinfo->max_v_samp_factor * DCTSIZE));
 256   }
 257
 258 #else /* !IDCT_SCALING_SUPPORTED */
 259
 260   /* Hardwire it to "no scaling" */
 261   cinfo->output_width = cinfo->image_width;
 262   cinfo->output_height = cinfo->image_height;
 263   /* jdinput.c has already initialized DCT_scaled_size to DCTSIZE,
 264    * and has computed unscaled downsampled_width and downsampled_height.
 265    */
 266
 267 #endif /* IDCT_SCALING_SUPPORTED */
 268
 269   /* Report number of components in selected colorspace. */
 270   /* Probably this should be in the color conversion module... */
 271   switch (cinfo->out_color_space) {
 272   case JCS_GRAYSCALE:
 273     cinfo->out_color_components = 1;
 274     break;
 275   case JCS_RGB:
 276 #if RGB_PIXELSIZE != 3
 277     cinfo->out_color_components = RGB_PIXELSIZE;
 278     break;
 279 #endif /* else share code with YCbCr */
 280   case JCS_YCbCr:
 281     cinfo->out_color_components = 3;
 282     break;
 283   case JCS_CMYK:
 284   case JCS_YCCK:
 285     cinfo->out_color_components = 4;
 286     break;
 287   default:                      /* else must be same colorspace as in file */
 288     cinfo->out_color_components = cinfo->num_components;
 289     break;
 290   }
 291   cinfo->output_components = (cinfo->quantize_colors ? 1 :
 292                               cinfo->out_color_components);
 293
 294   /* See if upsampler will want to emit more than one row at a time */
 295   if (use_merged_upsample(cinfo))
 296     cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
 297   else
 298     cinfo->rec_outbuf_height = 1;
 299 }
 300
 301
 302 /*
 303  * Several decompression processes need to range-limit values to the range
 304  * 0..MAXJSAMPLE; the input value may fall somewhat outside this range
 305  * due to noise introduced by quantization, roundoff error, etc.  These
 306  * processes are inner loops and need to be as fast as possible.  On most
 307  * machines, particularly CPUs with pipelines or instruction prefetch,
 308  * a (subscript-check-less) C table lookup
 309  *              x = sample_range_limit[x];
 310  * is faster than explicit tests
 311  *              if (x < 0)  x = 0;
 312  *              else if (x > MAXJSAMPLE)  x = MAXJSAMPLE;
 313  * These processes all use a common table prepared by the routine below.
 314  *
 315  * For most steps we can mathematically guarantee that the initial value
 316  * of x is within MAXJSAMPLE+1 of the legal range, so a table running from
 317  * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient.  But for the initial
 318  * limiting step (just after the IDCT), a wildly out-of-range value is
 319  * possible if the input data is corrupt.  To avoid any chance of indexing
 320  * off the end of memory and getting a bad-pointer trap, we perform the
 321  * post-IDCT limiting thus:
 322  *              x = range_limit[x & MASK];
 323  * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
 324  * samples.  Under normal circumstances this is more than enough range and
 325  * a correct output will be generated; with bogus input data the mask will
 326  * cause wraparound, and we will safely generate a bogus-but-in-range output.
 327  * For the post-IDCT step, we want to convert the data from signed to unsigned
 328  * representation by adding CENTERJSAMPLE at the same time that we limit it.
 329  * So the post-IDCT limiting table ends up looking like this:
 330  *   CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
 331  *   MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
 332  *   0          (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
 333  *   0,1,...,CENTERJSAMPLE-1
 334  * Negative inputs select values from the upper half of the table after
 335  * masking.
 336  *
 337  * We can save some space by overlapping the start of the post-IDCT table
 338  * with the simpler range limiting table.  The post-IDCT table begins at
 339  * sample_range_limit + CENTERJSAMPLE.
 340  *
 341  * Note that the table is allocated in near data space on PCs; it's small
 342  * enough and used often enough to justify this.
 343  */
 344
 345 LOCAL(void)
 346 prepare_range_limit_table (j_decompress_ptr cinfo)
 347 /* Allocate and fill in the sample_range_limit table */
 348 {
 349   /* Use a static table and allow negative subscripts of simple table */
 350
 351   cinfo->sample_range_limit = (JSAMPLE *) static_range_table + (MAXJSAMPLE+1);
 352
 353   /* This code is used to create the values for the static table used above */
 354
 355 #if 0
 356
 357   JSAMPLE * table;
 358   int i;
 359
 360   table = (JSAMPLE *)
 361     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 362                 (5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE));
 363   table += (MAXJSAMPLE+1);      /* allow negative subscripts of simple table */
 364   cinfo->sample_range_limit = table;
 365   /* First segment of "simple" table: limit[x] = 0 for x < 0 */
 366   MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
 367   /* Main part of "simple" table: limit[x] = x */
 368   for (i = 0; i <= MAXJSAMPLE; i++)
 369     table[i] = (JSAMPLE) i;
 370   table += CENTERJSAMPLE;       /* Point to where post-IDCT table starts */
 371   /* End of simple table, rest of first half of post-IDCT table */
 372   for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++)
 373     table[i] = MAXJSAMPLE;
 374   /* Second half of post-IDCT table */
 375   MEMZERO(table + (2 * (MAXJSAMPLE+1)),
 376           (2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE));
 377   MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE),
 378           cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE));
 379
 380 #endif /* 0 */
 381 }
 382
 383
 384 /*
 385  * Master selection of decompression modules.
 386  * This is done once at jpeg_start_decompress time.  We determine
 387  * which modules will be used and give them appropriate initialization calls.
 388  * We also initialize the decompressor input side to begin consuming data.
 389  *
 390  * Since jpeg_read_header has finished, we know what is in the SOF
 391  * and (first) SOS markers.  We also have all the application parameter
 392  * settings.
 393  */
 394
 395 LOCAL(void)
 396 master_selection (j_decompress_ptr cinfo)
 397 {
 398   my_master_ptr master = (my_master_ptr) cinfo->master;
 399   boolean use_c_buffer;
 400   long samplesperrow;
 401   JDIMENSION jd_samplesperrow;
 402
 403   /* Initialize dimensions and other stuff */
 404   jpeg_calc_output_dimensions(cinfo);
 405   prepare_range_limit_table(cinfo);
 406
 407   /* Width of an output scanline must be representable as JDIMENSION. */
 408   samplesperrow = (long) cinfo->output_width * (long) cinfo->out_color_components;
 409   jd_samplesperrow = (JDIMENSION) samplesperrow;
 410   if ((long) jd_samplesperrow != samplesperrow)
 411     ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
 412
 413   /* Initialize my private state */
 414   master->pass_number = 0;
 415   master->using_merged_upsample = use_merged_upsample(cinfo);
 416
 417   /* Color quantizer selection */
 418   master->quantizer_1pass = NULL;
 419   master->quantizer_2pass = NULL;
 420   /* No mode changes if not using buffered-image mode. */
 421   if (! cinfo->quantize_colors || ! cinfo->buffered_image) {
 422     cinfo->enable_1pass_quant = FALSE;
 423     cinfo->enable_external_quant = FALSE;
 424     cinfo->enable_2pass_quant = FALSE;
 425   }
 426   if (cinfo->quantize_colors) {
 427     if (cinfo->raw_data_out)
 428       ERREXIT(cinfo, JERR_NOTIMPL);
 429     /* 2-pass quantizer only works in 3-component color space. */
 430     if (cinfo->out_color_components != 3) {
 431       cinfo->enable_1pass_quant = TRUE;
 432       cinfo->enable_external_quant = FALSE;
 433       cinfo->enable_2pass_quant = FALSE;
 434       cinfo->colormap = NULL;
 435     } else if (cinfo->colormap != NULL) {
 436       cinfo->enable_external_quant = TRUE;
 437     } else if (cinfo->two_pass_quantize) {
 438       cinfo->enable_2pass_quant = TRUE;
 439     } else {
 440       cinfo->enable_1pass_quant = TRUE;
 441     }
 442
 443     if (cinfo->enable_1pass_quant) {
 444 #ifdef QUANT_1PASS_SUPPORTED
 445       jinit_1pass_quantizer(cinfo);
 446       master->quantizer_1pass = cinfo->cquantize;
 447 #else
 448       ERREXIT(cinfo, JERR_NOT_COMPILED);
 449 #endif
 450     }
 451
 452     /* We use the 2-pass code to map to external colormaps. */
 453     if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) {
 454 #ifdef QUANT_2PASS_SUPPORTED
 455       jinit_2pass_quantizer(cinfo);
 456       master->quantizer_2pass = cinfo->cquantize;
 457 #else
 458       ERREXIT(cinfo, JERR_NOT_COMPILED);
 459 #endif
 460     }
 461     /* If both quantizers are initialized, the 2-pass one is left active;
 462      * this is necessary for starting with quantization to an external map.
 463      */
 464   }
 465
 466   /* Post-processing: in particular, color conversion first */
 467   if (! cinfo->raw_data_out) {
 468     if (master->using_merged_upsample) {
 469 #ifdef UPSAMPLE_MERGING_SUPPORTED
 470       jinit_merged_upsampler(cinfo); /* does color conversion too */
 471 #else
 472       ERREXIT(cinfo, JERR_NOT_COMPILED);
 473 #endif
 474     } else {
 475       jinit_color_deconverter(cinfo);
 476       jinit_upsampler(cinfo);
 477     }
 478     jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant);
 479   }
 480   /* Inverse DCT */
 481   jinit_inverse_dct(cinfo);
 482   /* Entropy decoding: either Huffman or arithmetic coding. */
 483   if (cinfo->arith_code) {
 484     ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
 485   } else {
 486     if (cinfo->progressive_mode) {
 487 #ifdef D_PROGRESSIVE_SUPPORTED
 488       jinit_phuff_decoder(cinfo);
 489 #else
 490       ERREXIT(cinfo, JERR_NOT_COMPILED);
 491 #endif
 492     } else
 493       jinit_huff_decoder(cinfo);
 494   }
 495
 496   /* Initialize principal buffer controllers. */
 497   use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
 498   jinit_d_coef_controller(cinfo, use_c_buffer);
 499
 500   if (! cinfo->raw_data_out)
 501     jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */);
 502
 503   /* We can now tell the memory manager to allocate virtual arrays. */
 504   (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
 505
 506   /* Initialize input side of decompressor to consume first scan. */
 507   (*cinfo->inputctl->start_input_pass) (cinfo);
 508
 509 #ifdef D_MULTISCAN_FILES_SUPPORTED
 510   /* If jpeg_start_decompress will read the whole file, initialize
 511    * progress monitoring appropriately.  The input step is counted
 512    * as one pass.
 513    */
 514   if (cinfo->progress != NULL && ! cinfo->buffered_image &&
 515       cinfo->inputctl->has_multiple_scans) {
 516     int nscans;
 517     /* Estimate number of scans to set pass_limit. */
 518     if (cinfo->progressive_mode) {
 519       /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
 520       nscans = 2 + 3 * cinfo->num_components;
 521     } else {
 522       /* For a nonprogressive multiscan file, estimate 1 scan per component. */
 523       nscans = cinfo->num_components;
 524     }
 525     cinfo->progress->pass_counter = 0L;
 526     cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
 527     cinfo->progress->completed_passes = 0;
 528     cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2);
 529     /* Count the input pass as done */
 530     master->pass_number++;
 531   }
 532 #endif /* D_MULTISCAN_FILES_SUPPORTED */
 533 }
 534
 535
 536 /*
 537  * Per-pass setup.
 538  * This is called at the beginning of each output pass.  We determine which
 539  * modules will be active during this pass and give them appropriate
 540  * start_pass calls.  We also set is_dummy_pass to indicate whether this
 541  * is a "real" output pass or a dummy pass for color quantization.
 542  * (In the latter case, jdapistd.c will crank the pass to completion.)
 543  */
 544
 545 METHODDEF(void)
 546 prepare_for_output_pass (j_decompress_ptr cinfo)
 547 {
 548   my_master_ptr master = (my_master_ptr) cinfo->master;
 549
 550   if (master->pub.is_dummy_pass) {
 551 #ifdef QUANT_2PASS_SUPPORTED
 552     /* Final pass of 2-pass quantization */
 553     master->pub.is_dummy_pass = FALSE;
 554     (*cinfo->cquantize->start_pass) (cinfo, FALSE);
 555     (*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST);
 556     (*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST);
 557 #else
 558     ERREXIT(cinfo, JERR_NOT_COMPILED);
 559 #endif /* QUANT_2PASS_SUPPORTED */
 560   } else {
 561     if (cinfo->quantize_colors && cinfo->colormap == NULL) {
 562       /* Select new quantization method */
 563       if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) {
 564         cinfo->cquantize = master->quantizer_2pass;
 565         master->pub.is_dummy_pass = TRUE;
 566       } else if (cinfo->enable_1pass_quant) {
 567         cinfo->cquantize = master->quantizer_1pass;
 568       } else {
 569         ERREXIT(cinfo, JERR_MODE_CHANGE);
 570       }
 571     }
 572     (*cinfo->idct->start_pass) (cinfo);
 573     (*cinfo->coef->start_output_pass) (cinfo);
 574     if (! cinfo->raw_data_out) {
 575       if (! master->using_merged_upsample)
 576         (*cinfo->cconvert->start_pass) (cinfo);
 577       (*cinfo->upsample->start_pass) (cinfo);
 578       if (cinfo->quantize_colors)
 579         (*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass);
 580       (*cinfo->post->start_pass) (cinfo,
 581             (master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
 582       (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
 583     }
 584   }
 585
 586   /* Set up progress monitor's pass info if present */
 587   if (cinfo->progress != NULL) {
 588     cinfo->progress->completed_passes = master->pass_number;
 589     cinfo->progress->total_passes = master->pass_number +
 590                                     (master->pub.is_dummy_pass ? 2 : 1);
 591     /* In buffered-image mode, we assume one more output pass if EOI not
 592      * yet reached, but no more passes if EOI has been reached.
 593      */
 594     if (cinfo->buffered_image && ! cinfo->inputctl->eoi_reached) {
 595       cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1);
 596     }
 597   }
 598 }
 599
 600
 601 /*
 602  * Finish up at end of an output pass.
 603  */
 604
 605 METHODDEF(void)
 606 finish_output_pass (j_decompress_ptr cinfo)
 607 {
 608   my_master_ptr master = (my_master_ptr) cinfo->master;
 609
 610   if (cinfo->quantize_colors)
 611     (*cinfo->cquantize->finish_pass) (cinfo);
 612   master->pass_number++;
 613 }
 614
 615
 616 #ifdef D_MULTISCAN_FILES_SUPPORTED
 617
 618 /*
 619  * Switch to a new external colormap between output passes.
 620  */
 621
 622 GLOBAL(void)
 623 jpeg_new_colormap (j_decompress_ptr cinfo)
 624 {
 625   my_master_ptr master = (my_master_ptr) cinfo->master;
 626
 627   /* Prevent application from calling me at wrong times */
 628   if (cinfo->global_state != DSTATE_BUFIMAGE)
 629     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
 630
 631   if (cinfo->quantize_colors && cinfo->enable_external_quant &&
 632       cinfo->colormap != NULL) {
 633     /* Select 2-pass quantizer for external colormap use */
 634     cinfo->cquantize = master->quantizer_2pass;
 635     /* Notify quantizer of colormap change */
 636     (*cinfo->cquantize->new_color_map) (cinfo);
 637     master->pub.is_dummy_pass = FALSE; /* just in case */
 638   } else
 639     ERREXIT(cinfo, JERR_MODE_CHANGE);
 640 }
 641
 642 #endif /* D_MULTISCAN_FILES_SUPPORTED */
 643
 644
 645 /*
 646  * Initialize master decompression control and select active modules.
 647  * This is performed at the start of jpeg_start_decompress.
 648  */
 649
 650 GLOBAL(void)
 651 jinit_master_decompress (j_decompress_ptr cinfo)
 652 {
 653   my_master_ptr master;
 654
 655   master = (my_master_ptr)
 656       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
 657                                   SIZEOF(my_decomp_master));
 658   cinfo->master = (struct jpeg_decomp_master *) master;
 659   master->pub.prepare_for_output_pass = prepare_for_output_pass;
 660   master->pub.finish_output_pass = finish_output_pass;
 661
 662   master->pub.is_dummy_pass = FALSE;
 663
 664   master_selection(cinfo);
 665 }