From a859452d1d3d7292a2165c364f7b02a65926a237 Mon Sep 17 00:00:00 2001
From: Dirk Farin <dirk.farin@gmail.com>
Date: Tue, 15 Oct 2024 21:45:26 +0200
Subject: [PATCH] revert to old float-point reader when bit_cast is not
 available

---
 libheif/bitstream.cc                     | 49 ++++++++++++++----------
 libheif/codecs/uncompressed/unc_boxes.cc |  4 +-
 2 files changed, 31 insertions(+), 22 deletions(-)

diff --git a/libheif/bitstream.cc b/libheif/bitstream.cc
index 8da606b611..b6cdfb6db6 100644
--- a/libheif/bitstream.cc
+++ b/libheif/bitstream.cc
@@ -271,16 +271,6 @@ uint32_t BitstreamRange::read32()
                      (buf[3]));
 }
 
-float BitstreamRange::read_float32()
-{
-#if __cpp_lib_bit_cast >= 201806L
-  uint32_t i = read32();
-  return std::bit_cast<float>(i); // this works directly on the value layout, thus we do not have to worry about memory layout
-#else
-  assert(false); // compiler too old to support bit_cast
-#endif
-}
-
 
 uint64_t BitstreamRange::read_uint(int len)
 {
@@ -354,6 +344,35 @@ int64_t BitstreamRange::read64s()
 }
 
 
+float BitstreamRange::read_float32()
+{
+#if __cpp_lib_bit_cast >= 201806L
+  uint32_t i = read32();
+  return std::bit_cast<float>(i); // this works directly on the value layout, thus we do not have to worry about memory layout
+#else
+  // compiler too old to support bit_cast
+
+  int i = read32();
+  float f;
+  memcpy(&f, &i, sizeof(float));
+  return f;
+#endif
+}
+
+
+void StreamWriter::write_float32(float v)
+{
+#if __cpp_lib_bit_cast >= 201806L
+  write32(std::bit_cast<uint32_t>(v)); // this works directly on the value layout, thus we do not have to worry about memory layout
+#else
+  // compiler too old to support bit_cast
+  uint32_t i;
+  memcpy(&i, &v, sizeof(float));
+  write32(i);
+#endif
+}
+
+
 std::string BitstreamRange::read_string()
 {
   std::string str;
@@ -699,16 +718,6 @@ void StreamWriter::write32(uint32_t v)
 }
 
 
-void StreamWriter::write_float32(float v)
-{
-#if __cpp_lib_bit_cast >= 201806L
-  write32(std::bit_cast<uint32_t>(v)); // this works directly on the value layout, thus we do not have to worry about memory layout
-#else
-  assert(false); // compiler too old to support bit_cast
-#endif
-}
-
-
 void StreamWriter::write32s(int32_t v32s)
 {
   uint32_t v;
diff --git a/libheif/codecs/uncompressed/unc_boxes.cc b/libheif/codecs/uncompressed/unc_boxes.cc
index 2eed7c1314..a3f9895f19 100644
--- a/libheif/codecs/uncompressed/unc_boxes.cc
+++ b/libheif/codecs/uncompressed/unc_boxes.cc
@@ -646,7 +646,7 @@ Error Box_cpat::parse(BitstreamRange& range, const heif_security_limits* limits)
     for (uint16_t j = 0; j < m_pattern_width; j++) {
       PatternComponent component{};
       component.component_index = range.read32();
-      component.component_gain = range.readFloat32();
+      component.component_gain = range.read_float32();
       m_components[i] = component;
     }
   }
@@ -686,7 +686,7 @@ Error Box_cpat::write(StreamWriter& writer) const
 
   for (const auto& component : m_components) {
     writer.write32(component.component_index);
-    writer.writeFloat32(component.component_gain);
+    writer.write_float32(component.component_gain);
   }
 
   prepend_header(writer, box_start);