Merge pull request #1353 from strukturag/fix-unci-endianness-issue

unci: endianness correction
strukturag · Oct 29, 2024 · 3f7cf77 · 3f7cf77
2 parents 0e9743e + dc49f57
commit 3f7cf77
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Showing 5 changed files with 366 additions and 657 deletions.
diff --git a/libheif/codecs/uncompressed/decoder_abstract.cc b/libheif/codecs/uncompressed/decoder_abstract.cc
@@ -56,12 +56,32 @@ void AbstractDecoder::buildChannelList(std::shared_ptr<HeifPixelImage>& img)
   }
 }
 
+void AbstractDecoder::memcpy_to_native_endian(uint8_t* dst, uint32_t value, uint32_t bytes_per_sample)
+{
+  // TODO: this assumes that the file endianness is always big-endian. The endianness flags in the uncC header are not taken into account yet.
+
+  if (bytes_per_sample==1) {
+    *dst = static_cast<uint8_t>(value);
+    return;
+  }
+  else if (std::endian::native == std::endian::big) {
+    for (uint32_t i = 0; i < bytes_per_sample; i++) {
+      dst[bytes_per_sample - 1 - i] = static_cast<uint8_t>((value >> (i * 8)) & 0xFF);
+    }
+  }
+  else {
+    for (uint32_t i = 0; i < bytes_per_sample; i++) {
+      dst[i] = static_cast<uint8_t>((value >> (i * 8)) & 0xFF);
+    }
+  }
+}
+
 void AbstractDecoder::processComponentSample(UncompressedBitReader& srcBits, const ChannelListEntry& entry, uint64_t dst_row_offset, uint32_t tile_column, uint32_t tile_x)
 {
   uint64_t dst_col_number = static_cast<uint64_t>(tile_column) * entry.tile_width + tile_x;
   uint64_t dst_column_offset = dst_col_number * entry.bytes_per_component_sample;
-  int val = srcBits.get_bits(entry.bits_per_component_sample);
-  memcpy(entry.dst_plane + dst_row_offset + dst_column_offset, &val, entry.bytes_per_component_sample);
+  int val = srcBits.get_bits(entry.bits_per_component_sample); // get_bits() reads input in big-endian order
+  memcpy_to_native_endian(entry.dst_plane + dst_row_offset + dst_column_offset, val, entry.bytes_per_component_sample);
 }
 
 // Handles the case where a row consists of a single component type
@@ -85,7 +105,7 @@ void AbstractDecoder::processComponentTileSample(UncompressedBitReader& srcBits,
 {
   uint64_t dst_sample_offset = uint64_t{tile_x} * entry.bytes_per_component_sample;
   int val = srcBits.get_bits(entry.bits_per_component_sample);
-  memcpy(entry.dst_plane + dst_offset + dst_sample_offset, &val, entry.bytes_per_component_sample);
+  memcpy_to_native_endian(entry.dst_plane + dst_offset + dst_sample_offset, val, entry.bytes_per_component_sample);
 }
 
 // Handles the case where a row consists of a single component type

diff --git a/libheif/codecs/uncompressed/decoder_abstract.h b/libheif/codecs/uncompressed/decoder_abstract.h
@@ -201,6 +201,9 @@ class AbstractDecoder
                                  std::vector<uint8_t> compressed_data,
                                  std::vector<uint8_t>* data) const;
 
+protected:
+  void memcpy_to_native_endian(uint8_t* dst, uint32_t value, uint32_t bytes_per_sample);
+
 private:
   ChannelListEntry buildChannelListEntry(Box_uncC::Component component, std::shared_ptr<HeifPixelImage>& img);
 };

diff --git a/libheif/codecs/uncompressed/decoder_mixed_interleave.cc b/libheif/codecs/uncompressed/decoder_mixed_interleave.cc
@@ -106,9 +106,9 @@ void MixedInterleaveDecoder::processTile(UncompressedBitReader& srcBits, uint32_
               uint64_t dst_column_number = out_x0 + tile_x;
               uint64_t dst_column_offset = dst_column_number * entry.bytes_per_component_sample;
               int val = srcBits.get_bits(entry.bytes_per_component_sample * 8);
-              memcpy(entry.dst_plane + dst_row_offset + dst_column_offset, &val, entry.bytes_per_component_sample);
+              memcpy_to_native_endian(entry.dst_plane + dst_row_offset + dst_column_offset, val, entry.bytes_per_component_sample);
               val = srcBits.get_bits(entry.bytes_per_component_sample * 8);
-              memcpy(entry.other_chroma_dst_plane + dst_row_offset + dst_column_offset, &val, entry.bytes_per_component_sample);
+              memcpy_to_native_endian(entry.other_chroma_dst_plane + dst_row_offset + dst_column_offset, val, entry.bytes_per_component_sample);
             }
             haveProcessedChromaForThisTile = true;
           }