source_manager.cc (3179B)
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 }