diff options
Diffstat (limited to 'third_party/webrtc/src/webrtc/common_audio/signal_processing/resample_by_2.c')
| -rw-r--r-- | third_party/webrtc/src/webrtc/common_audio/signal_processing/resample_by_2.c | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/third_party/webrtc/src/webrtc/common_audio/signal_processing/resample_by_2.c b/third_party/webrtc/src/webrtc/common_audio/signal_processing/resample_by_2.c new file mode 100644 index 00000000..dcba82e3 --- /dev/null +++ b/third_party/webrtc/src/webrtc/common_audio/signal_processing/resample_by_2.c @@ -0,0 +1,183 @@ +/* + * Copyright (c) 2011 The WebRTC project authors. All Rights Reserved. + * + * Use of this source code is governed by a BSD-style license + * that can be found in the LICENSE file in the root of the source + * tree. An additional intellectual property rights grant can be found + * in the file PATENTS. All contributing project authors may + * be found in the AUTHORS file in the root of the source tree. + */ + + +/* + * This file contains the resampling by two functions. + * The description header can be found in signal_processing_library.h + * + */ + +#include "webrtc/common_audio/signal_processing/include/signal_processing_library.h" + +#ifdef WEBRTC_ARCH_ARM_V7 + +// allpass filter coefficients. +static const uint32_t kResampleAllpass1[3] = {3284, 24441, 49528 << 15}; +static const uint32_t kResampleAllpass2[3] = + {12199, 37471 << 15, 60255 << 15}; + +// Multiply two 32-bit values and accumulate to another input value. +// Return: state + ((diff * tbl_value) >> 16) + +static __inline int32_t MUL_ACCUM_1(int32_t tbl_value, + int32_t diff, + int32_t state) { + int32_t result; + __asm __volatile ("smlawb %0, %1, %2, %3": "=r"(result): "r"(diff), + "r"(tbl_value), "r"(state)); + return result; +} + +// Multiply two 32-bit values and accumulate to another input value. +// Return: Return: state + (((diff << 1) * tbl_value) >> 32) +// +// The reason to introduce this function is that, in case we can't use smlawb +// instruction (in MUL_ACCUM_1) due to input value range, we can still use +// smmla to save some cycles. + +static __inline int32_t MUL_ACCUM_2(int32_t tbl_value, + int32_t diff, + int32_t state) { + int32_t result; + __asm __volatile ("smmla %0, %1, %2, %3": "=r"(result): "r"(diff << 1), + "r"(tbl_value), "r"(state)); + return result; +} + +#else + +// allpass filter coefficients. +static const uint16_t kResampleAllpass1[3] = {3284, 24441, 49528}; +static const uint16_t kResampleAllpass2[3] = {12199, 37471, 60255}; + +// Multiply a 32-bit value with a 16-bit value and accumulate to another input: +#define MUL_ACCUM_1(a, b, c) WEBRTC_SPL_SCALEDIFF32(a, b, c) +#define MUL_ACCUM_2(a, b, c) WEBRTC_SPL_SCALEDIFF32(a, b, c) + +#endif // WEBRTC_ARCH_ARM_V7 + + +// decimator +#if !defined(MIPS32_LE) +void WebRtcSpl_DownsampleBy2(const int16_t* in, size_t len, + int16_t* out, int32_t* filtState) { + int32_t tmp1, tmp2, diff, in32, out32; + size_t i; + + register int32_t state0 = filtState[0]; + register int32_t state1 = filtState[1]; + register int32_t state2 = filtState[2]; + register int32_t state3 = filtState[3]; + register int32_t state4 = filtState[4]; + register int32_t state5 = filtState[5]; + register int32_t state6 = filtState[6]; + register int32_t state7 = filtState[7]; + + for (i = (len >> 1); i > 0; i--) { + // lower allpass filter + in32 = (int32_t)(*in++) << 10; + diff = in32 - state1; + tmp1 = MUL_ACCUM_1(kResampleAllpass2[0], diff, state0); + state0 = in32; + diff = tmp1 - state2; + tmp2 = MUL_ACCUM_2(kResampleAllpass2[1], diff, state1); + state1 = tmp1; + diff = tmp2 - state3; + state3 = MUL_ACCUM_2(kResampleAllpass2[2], diff, state2); + state2 = tmp2; + + // upper allpass filter + in32 = (int32_t)(*in++) << 10; + diff = in32 - state5; + tmp1 = MUL_ACCUM_1(kResampleAllpass1[0], diff, state4); + state4 = in32; + diff = tmp1 - state6; + tmp2 = MUL_ACCUM_1(kResampleAllpass1[1], diff, state5); + state5 = tmp1; + diff = tmp2 - state7; + state7 = MUL_ACCUM_2(kResampleAllpass1[2], diff, state6); + state6 = tmp2; + + // add two allpass outputs, divide by two and round + out32 = (state3 + state7 + 1024) >> 11; + + // limit amplitude to prevent wrap-around, and write to output array + *out++ = WebRtcSpl_SatW32ToW16(out32); + } + + filtState[0] = state0; + filtState[1] = state1; + filtState[2] = state2; + filtState[3] = state3; + filtState[4] = state4; + filtState[5] = state5; + filtState[6] = state6; + filtState[7] = state7; +} +#endif // #if defined(MIPS32_LE) + + +void WebRtcSpl_UpsampleBy2(const int16_t* in, size_t len, + int16_t* out, int32_t* filtState) { + int32_t tmp1, tmp2, diff, in32, out32; + size_t i; + + register int32_t state0 = filtState[0]; + register int32_t state1 = filtState[1]; + register int32_t state2 = filtState[2]; + register int32_t state3 = filtState[3]; + register int32_t state4 = filtState[4]; + register int32_t state5 = filtState[5]; + register int32_t state6 = filtState[6]; + register int32_t state7 = filtState[7]; + + for (i = len; i > 0; i--) { + // lower allpass filter + in32 = (int32_t)(*in++) << 10; + diff = in32 - state1; + tmp1 = MUL_ACCUM_1(kResampleAllpass1[0], diff, state0); + state0 = in32; + diff = tmp1 - state2; + tmp2 = MUL_ACCUM_1(kResampleAllpass1[1], diff, state1); + state1 = tmp1; + diff = tmp2 - state3; + state3 = MUL_ACCUM_2(kResampleAllpass1[2], diff, state2); + state2 = tmp2; + + // round; limit amplitude to prevent wrap-around; write to output array + out32 = (state3 + 512) >> 10; + *out++ = WebRtcSpl_SatW32ToW16(out32); + + // upper allpass filter + diff = in32 - state5; + tmp1 = MUL_ACCUM_1(kResampleAllpass2[0], diff, state4); + state4 = in32; + diff = tmp1 - state6; + tmp2 = MUL_ACCUM_2(kResampleAllpass2[1], diff, state5); + state5 = tmp1; + diff = tmp2 - state7; + state7 = MUL_ACCUM_2(kResampleAllpass2[2], diff, state6); + state6 = tmp2; + + // round; limit amplitude to prevent wrap-around; write to output array + out32 = (state7 + 512) >> 10; + *out++ = WebRtcSpl_SatW32ToW16(out32); + } + + filtState[0] = state0; + filtState[1] = state1; + filtState[2] = state2; + filtState[3] = state3; + filtState[4] = state4; + filtState[5] = state5; + filtState[6] = state6; + filtState[7] = state7; +} |