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AVX optimizations for the convertBuffer function #241

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AVX optimizations for the convertBuffer function #241

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73ee776
AVX optimizations for the convertBuffer function
eloi-loomai Apr 10, 2020
013c1ea
minor fix
eloi-loomai Apr 10, 2020
fd7ad3f
compilation fix
eloi-loomai Apr 11, 2020
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24 changes: 24 additions & 0 deletions CMakeLists.txt
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Expand Up @@ -64,6 +64,30 @@ if (CMAKE_COMPILER_IS_GNUCXX)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall")
endif (CMAKE_COMPILER_IS_GNUCXX)

#default SIMD configuration uses AVX2 build flags
if(NOT DEFAULT_SIMD_FLAGS)
set(DEFAULT_SIMD_FLAGS "AVX2")
endif()

SET(ENABLE_SIMD_FLAGS "${DEFAULT_SIMD_FLAGS}" CACHE STRING "Set compiler SIMD flags")
SET_PROPERTY(CACHE ENABLE_SIMD_FLAGS PROPERTY STRINGS none AVX2)

#set up according to your own system environment
#Windows
if(CMAKE_CXX_COMPILER_ID MATCHES "MSVC"
OR (CMAKE_CXX_COMPILER_ID MATCHES "Clang" AND CMAKE_CXX_SIMULATE_ID MATCHES "MSVC"))
if(${ENABLE_SIMD_FLAGS} MATCHES "AVX2")
add_definitions(/arch:AVX2 /D__AVX__)
message(STATUS "Enabling AVX2 instructions")
endif()
#Linux
else()
if(${ENABLE_SIMD_FLAGS} MATCHES "AVX")
add_definitions(-mmmx -msse -msse2 -msse3 -mssse3 -msse4.1 -msse4.2 -mpopcnt -mavx -mavx2 -mfma)
message(STATUS "Enabling AVX2 instructions")
endif()
endif()

# Add debug flags
if (CMAKE_BUILD_TYPE STREQUAL "Debug")
add_definitions(-D__RTAUDIO_DEBUG__)
Expand Down
111 changes: 95 additions & 16 deletions RtAudio.cpp
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Expand Up @@ -49,6 +49,13 @@
#include <cmath>
#include <algorithm>

#if __SSE2__
#include <emmintrin.h>
#endif
#if __AVX__
#include <immintrin.h>
#endif

// Static variable definitions.
const unsigned int RtApi::MAX_SAMPLE_RATES = 14;
const unsigned int RtApi::SAMPLE_RATES[] = {
Expand Down Expand Up @@ -537,7 +544,7 @@ struct CoreHandle {
bool internalDrain; // Indicates if stop is initiated from callback or not.

CoreHandle()
:deviceBuffer(0), drainCounter(0), internalDrain(false) { nStreams[0] = 1; nStreams[1] = 1; id[0] = 0; id[1] = 0; xrun[0] = false; xrun[1] = false; }
:deviceBuffer(0), drainCounter(0), internalDrain(false) { iStream[0] = 0; iStream[1] = 0; nStreams[0] = 1; nStreams[1] = 1; id[0] = 0; id[1] = 0; xrun[0] = false; xrun[1] = false; }
};

RtApiCore:: RtApiCore()
Expand Down Expand Up @@ -10386,6 +10393,12 @@ void RtApi :: setConvertInfo( StreamMode mode, unsigned int firstChannel )

void RtApi :: convertBuffer( char *outBuffer, char *inBuffer, ConvertInfo &info )
{
#ifdef __AVX__
static const float kBias[8] = {0.5f, 0.5f, 0.5f, 0.5f, 0.5f, 0.5f, 0.5f, 0.5f};
static const float kScale[8] = {32767.5f, 32767.5f, 32767.5f, 32767.5f, 32767.5f, 32767.5f, 32767.5f, 32767.5f};
static const float kScaleI[8] = {1.0f / 32767.5f, 1.0f / 32767.5f, 1.0f / 32767.5f, 1.0f / 32767.5f, 1.0f / 32767.5f, 1.0f / 32767.5f, 1.0f / 32767.5f, 1.0f / 32767.5f};
#endif

// This function does format conversion, input/output channel compensation, and
// data interleaving/deinterleaving. 24-bit integers are assumed to occupy
// the lower three bytes of a 32-bit integer.
Expand All @@ -10395,6 +10408,12 @@ void RtApi :: convertBuffer( char *outBuffer, char *inBuffer, ConvertInfo &info
( stream_.nDeviceChannels[0] < stream_.nDeviceChannels[1] ) )
memset( outBuffer, 0, stream_.bufferSize * info.outJump * formatBytes( info.outFormat ) );

if (info.outFormat == info.inFormat && info.channels == 1)
{
std::memcpy(outBuffer, inBuffer, stream_.bufferSize * formatBytes(info.outFormat));
return;
}

int j;
if (info.outFormat == RTAUDIO_FLOAT64) {
Float64 scale;
Expand Down Expand Up @@ -10493,15 +10512,44 @@ void RtApi :: convertBuffer( char *outBuffer, char *inBuffer, ConvertInfo &info
}
else if (info.inFormat == RTAUDIO_SINT16) {
Int16 *in = (Int16 *)inBuffer;
scale = (Float32) ( 1.0 / 32767.5 );
for (unsigned int i=0; i<stream_.bufferSize; i++) {
for (j=0; j<info.channels; j++) {
out[info.outOffset[j]] = (Float32) in[info.inOffset[j]];
out[info.outOffset[j]] += 0.5;
out[info.outOffset[j]] *= scale;
}
in += info.inJump;
out += info.outJump;
scale = (Float32) ( 1.0f / 32767.5f );
if (info.channels == 1)
{
#if __AVX__
if (stream_.bufferSize >= 8 && stream_.bufferSize % 8 == 0)
{
__m256 _bias = _mm256_broadcast_ss(kBias);
__m256 _scale = _mm256_broadcast_ss(kScaleI);
for (unsigned int i=0; i<stream_.bufferSize; i+=8) {
__m128i x = _mm_loadu_si128((const __m128i*)(in + i));
__m256i x_unpacked = _mm256_cvtepi16_epi32(x);
__m256 converted = _mm256_cvtepi32_ps(x_unpacked);
converted = _mm256_mul_ps(_mm256_add_ps(converted, _bias), _scale);
_mm256_store_ps(out + i, converted);
}
}
else{
for (unsigned int i=0; i<stream_.bufferSize; ++i) {
out[i] = ((Float32) in[i] + 0.5) * scale;
}
}
#else
for (unsigned int i=0; i<stream_.bufferSize; ++i) {
out[i] = ((Float32) in[i] + 0.5) * scale;
}
#endif
}
else
{
for (unsigned int i=0; i<stream_.bufferSize; i++) {
for (j=0; j<info.channels; j++) {
out[info.outOffset[j]] = (Float32) in[info.inOffset[j]];
out[info.outOffset[j]] += 0.5;
out[info.outOffset[j]] *= scale;
}
in += info.inJump;
out += info.outJump;
}
}
}
else if (info.inFormat == RTAUDIO_SINT24) {
Expand Down Expand Up @@ -10732,12 +10780,43 @@ void RtApi :: convertBuffer( char *outBuffer, char *inBuffer, ConvertInfo &info
}
else if (info.inFormat == RTAUDIO_FLOAT32) {
Float32 *in = (Float32 *)inBuffer;
for (unsigned int i=0; i<stream_.bufferSize; i++) {
for (j=0; j<info.channels; j++) {
out[info.outOffset[j]] = (Int16) (in[info.inOffset[j]] * 32767.5 - 0.5);
}
in += info.inJump;
out += info.outJump;
if (info.channels == 1)
{
#if __AVX__
if (stream_.bufferSize >= 8 && stream_.bufferSize % 8 == 0)
{
__m256 _bias = _mm256_broadcast_ss(kBias);
__m256 _scale = _mm256_broadcast_ss(kScale);
for (unsigned int i=0; i<stream_.bufferSize; i+=8) {
__m256 in_x8 = _mm256_load_ps(in + i);
__m256 scaled_bias = _mm256_fmsub_ps(in_x8, _scale, _bias);
__m256i x = _mm256_cvtps_epi32(scaled_bias);
__m128i xlo = _mm256_extractf128_si256(x, 0);
__m128i xhi = _mm256_extractf128_si256(x, 1);
__m128i converted = _mm_packs_epi32(xlo, xhi);
_mm_store_si128((__m128i *)(out + i), converted);
}
}
else{
for (unsigned int i=0; i<stream_.bufferSize; ++i) {
out[i] = (Int16) (in[i] * 32767.5 - 0.5);
}
}
#else
for (unsigned int i=0; i<stream_.bufferSize; ++i) {
out[i] = (Int16) (in[i] * 32767.5 - 0.5);
}
#endif
}
else
{
for (unsigned int i=0; i<stream_.bufferSize; i++) {
for (j=0; j<info.channels; j++) {
out[info.outOffset[j]] = (Int16) (in[info.inOffset[j]] * 32767.5 - 0.5);
}
in += info.inJump;
out += info.outJump;
}
}
}
else if (info.inFormat == RTAUDIO_FLOAT64) {
Expand Down