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decoder/dsf: simplify dsf_to_pcm_order()

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Don't pass the buffer size to the function, as it's known at compile
time.  Use "restrict" on the pointer arguments, and merge the two
loops, which allows the compiler to optimize this loop with a few SSE2
instructions.
This commit is contained in:
Max Kellermann
2014-08-22 06:58:08 +02:00
parent dedc2986c6
commit d8782ce5fd
1 changed files with 5 additions and 10 deletions
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15
src/decoder/plugins/DsfDecoderPlugin.cxx
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@@ -195,16 +195,11 @@ bit_reverse_buffer(uint8_t *p, uint8_t *end)
* order.
*/
static void
dsf_to_pcm_order(uint8_t *dest, const uint8_t *src, size_t nrbytes)
dsf_to_pcm_order(uint8_t *gcc_restrict dest, const uint8_t *gcc_restrict src)
{
for (size_t i = 0, j = 0; i < nrbytes; i += 2) {
dest[i] = src[j];
j++;
}
for (size_t i = 1, j = 0; i < nrbytes; i += 2) {
dest[i] = src[DSF_BLOCK_SIZE + j];
j++;
for (size_t i = 0; i < DSF_BLOCK_SIZE; ++i) {
dest[2 * i] = src[i];
dest[2 * i + 1] = src[DSF_BLOCK_SIZE + i];
}
}
@@ -236,7 +231,7 @@ dsf_decode_chunk(Decoder &decoder, InputStream &is,
bit_reverse_buffer(buffer, buffer + block_size);
uint8_t interleaved_buffer[DSF_BLOCK_SIZE * 2];
dsf_to_pcm_order(interleaved_buffer, buffer, block_size);
dsf_to_pcm_order(interleaved_buffer, buffer);
const auto cmd = decoder_data(decoder, is,
interleaved_buffer, block_size,