Add an optimized FIFO writer for 32-bit words
Also improve the FIFO comments
Test: not yet tested
Change-Id: I29b645c05800491661ec81e816a38544b64fcc90
diff --git a/audio_utils/fifo_writer32.cpp b/audio_utils/fifo_writer32.cpp
new file mode 100644
index 0000000..7551e67
--- /dev/null
+++ b/audio_utils/fifo_writer32.cpp
@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <atomic>
+#include <stdlib.h>
+#include <string.h>
+
+// TODO templatize int32_t
+
+#include <audio_utils/fifo_writer32.h>
+
+static inline void memcpyWords(int32_t *dst, const int32_t *src, uint32_t count)
+{
+ switch (count) {
+ case 0: break;
+// TODO templatize here also, but first confirm no performance regression compared to current
+#define _(n) \
+ case n: { \
+ struct s##n { int32_t a[n]; }; \
+ *(struct s##n *)dst = *(const struct s##n *)src; \
+ break; \
+ }
+ _(1) _(2) _(3) _(4) _(5) _(6) _(7) _(8) _(9) _(10) _(11) _(12) _(13) _(14) _(15) _(16)
+#undef _
+ default:
+ memcpy(dst, src, count * sizeof(int32_t));
+ break;
+ }
+}
+
+audio_utils_fifo_writer32::audio_utils_fifo_writer32(audio_utils_fifo& fifo) :
+ mLocalRear(0), mFrameCountP2(fifo.mFrameCountP2), mBuffer((int32_t *) fifo.mBuffer),
+ mWriterRear(fifo.mWriterRear)
+{
+ if (fifo.mFrameSize != sizeof(int32_t) || fifo.mFudgeFactor != 0 ||
+ ((size_t) mBuffer & ((sizeof(int32_t) - 1))) != 0) {
+ abort();
+ }
+}
+
+audio_utils_fifo_writer32::~audio_utils_fifo_writer32()
+{
+}
+
+void audio_utils_fifo_writer32::write(const int32_t *buffer, uint32_t count)
+ __attribute__((no_sanitize("integer"))) // mLocalRear += can wrap
+{
+ uint32_t availToWrite = mFrameCountP2;
+ if (availToWrite > count) {
+ availToWrite = count;
+ }
+ uint32_t rearOffset = mLocalRear & (mFrameCountP2 - 1);
+ uint32_t part1 = mFrameCountP2 - rearOffset;
+ if (part1 > availToWrite) {
+ part1 = availToWrite;
+ }
+ memcpyWords(&mBuffer[rearOffset], buffer, part1);
+ // TODO apply this simplification to other copies of the code
+ uint32_t part2 = availToWrite - part1;
+ memcpyWords(&mBuffer[0], &buffer[part1], part2);
+ mLocalRear += availToWrite;
+}