[APU] Resolved crash related to negative amount of bits to copy

This is likely due to hitting somehow valid frame in invalid data

src/xenia/apu/xma_context.cc

@@ -597,9 +597,19 @@ void XmaContext::Decode(XMA_CONTEXT_DATA* data) {
       std::memset(xma_frame_.data(), 0, xma_frame_.size());
 
       {
-        auto offset =
-            stream.Copy(xma_frame_.data() + 1,
-                        std::min(split_frame_len_, split_frame_len_partial_));
+        int32_t bits_to_copy =
+            std::min(split_frame_len_, split_frame_len_partial_);
+
+        if (!stream.IsOffsetValid(bits_to_copy)) {
+          XELOGAPU(
+              "XmaContext {}: Error - Invalid amount of bits to copy! "
+              "split_frame_len: {}, split_partial: {}, offset_bits: {}",
+              id(), split_frame_len_, split_frame_len_partial_,
+              stream.offset_bits());
+          SwapInputBuffer(data);
+          return;
+        }
+        auto offset = stream.Copy(xma_frame_.data() + 1, bits_to_copy);
         assert_true(offset < 8);
         split_frame_padding_start_ = static_cast<uint8_t>(offset);
       }

src/xenia/base/bit_stream.cc

@@ -29,6 +29,16 @@ void BitStream::SetOffset(size_t offset_bits) {
 
 size_t BitStream::BitsRemaining() { return size_bits_ - offset_bits_; }
 
+bool BitStream::IsOffsetValid(size_t num_bits) {
+  size_t offset_bytes = offset_bits_ >> 3;
+  size_t rel_offset_bits = offset_bits_ - (offset_bytes << 3);
+
+  if (rel_offset_bits && int32_t(num_bits - 8 - rel_offset_bits) < 0) {
+    return false;
+  }
+  return true;
+}
+
 uint64_t BitStream::Peek(size_t num_bits) {
   // FYI: The reason we can't copy more than 57 bits is:
   // 57 = 7 * 8 + 1 - that can only span a maximum of 8 bytes.

src/xenia/base/bit_stream.h

@@ -28,6 +28,7 @@ class BitStream {
   void Advance(size_t num_bits);
   void SetOffset(size_t offset_bits);
   size_t BitsRemaining();
+  bool IsOffsetValid(size_t num_bits);
 
   // Note: num_bits MUST be in the range 0-57 (inclusive)
   uint64_t Peek(size_t num_bits);