third_party/jpeg-xl/lib/jpegli/source_manager.cc

   1 // Copyright (c) the JPEG XL Project Authors. All rights reserved.
   2 //
   3 // Use of this source code is governed by a BSD-style
   4 // license that can be found in the LICENSE file.
   5
   6 #include "lib/jpegli/decode.h"
   7 #include "lib/jpegli/error.h"
   8 #include "lib/jpegli/memory_manager.h"
   9
  10 namespace jpegli {
  11
  12 void init_mem_source(j_decompress_ptr cinfo) {}
  13 void init_stdio_source(j_decompress_ptr cinfo) {}
  14
  15 void skip_input_data(j_decompress_ptr cinfo, long num_bytes) {
  16   if (num_bytes <= 0) return;
  17   while (num_bytes > static_cast<long>(cinfo->src->bytes_in_buffer)) {
  18     num_bytes -= cinfo->src->bytes_in_buffer;
  19     (*cinfo->src->fill_input_buffer)(cinfo);
  20   }
  21   cinfo->src->next_input_byte += num_bytes;
  22   cinfo->src->bytes_in_buffer -= num_bytes;
  23 }
  24
  25 void term_source(j_decompress_ptr cinfo) {}
  26
  27 boolean EmitFakeEoiMarker(j_decompress_ptr cinfo) {
  28   static constexpr uint8_t kFakeEoiMarker[2] = {0xff, 0xd9};
  29   cinfo->src->next_input_byte = kFakeEoiMarker;
  30   cinfo->src->bytes_in_buffer = 2;
  31   return TRUE;
  32 }
  33
  34 constexpr size_t kStdioBufferSize = 64 << 10;
  35
  36 struct StdioSourceManager {
  37   jpeg_source_mgr pub;
  38   FILE* f;
  39   uint8_t* buffer;
  40
  41   static boolean fill_input_buffer(j_decompress_ptr cinfo) {
  42     auto src = reinterpret_cast<StdioSourceManager*>(cinfo->src);
  43     size_t num_bytes_read = fread(src->buffer, 1, kStdioBufferSize, src->f);
  44     if (num_bytes_read == 0) {
  45       return EmitFakeEoiMarker(cinfo);
  46     }
  47     src->pub.next_input_byte = src->buffer;
  48     src->pub.bytes_in_buffer = num_bytes_read;
  49     return TRUE;
  50   }
  51 };
  52
  53 }  // namespace jpegli
  54
  55 void jpegli_mem_src(j_decompress_ptr cinfo, const unsigned char* inbuffer,
  56                     unsigned long insize) {
  57   if (cinfo->src && cinfo->src->init_source != jpegli::init_mem_source) {
  58     JPEGLI_ERROR("jpegli_mem_src: a different source manager was already set");
  59   }
  60   if (!cinfo->src) {
  61     cinfo->src = jpegli::Allocate<jpeg_source_mgr>(cinfo, 1);
  62   }
  63   cinfo->src->next_input_byte = inbuffer;
  64   cinfo->src->bytes_in_buffer = insize;
  65   cinfo->src->init_source = jpegli::init_mem_source;
  66   cinfo->src->fill_input_buffer = jpegli::EmitFakeEoiMarker;
  67   cinfo->src->skip_input_data = jpegli::skip_input_data;
  68   cinfo->src->resync_to_restart = jpegli_resync_to_restart;
  69   cinfo->src->term_source = jpegli::term_source;
  70 }
  71
  72 void jpegli_stdio_src(j_decompress_ptr cinfo, FILE* infile) {
  73   if (cinfo->src && cinfo->src->init_source != jpegli::init_stdio_source) {
  74     JPEGLI_ERROR("jpeg_stdio_src: a different source manager was already set");
  75   }
  76   if (!cinfo->src) {
  77     cinfo->src = reinterpret_cast<jpeg_source_mgr*>(
  78         jpegli::Allocate<jpegli::StdioSourceManager>(cinfo, 1));
  79   }
  80   auto src = reinterpret_cast<jpegli::StdioSourceManager*>(cinfo->src);
  81   src->f = infile;
  82   src->buffer = jpegli::Allocate<uint8_t>(cinfo, jpegli::kStdioBufferSize);
  83   src->pub.next_input_byte = src->buffer;
  84   src->pub.bytes_in_buffer = 0;
  85   src->pub.init_source = jpegli::init_stdio_source;
  86   src->pub.fill_input_buffer = jpegli::StdioSourceManager::fill_input_buffer;
  87   src->pub.skip_input_data = jpegli::skip_input_data;
  88   src->pub.resync_to_restart = jpegli_resync_to_restart;
  89   src->pub.term_source = jpegli::term_source;
  90 }