diff options
Diffstat (limited to 'third_party/libwebrtc/common_audio/signal_processing/downsample_fast.c')
-rw-r--r-- | third_party/libwebrtc/common_audio/signal_processing/downsample_fast.c | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/third_party/libwebrtc/common_audio/signal_processing/downsample_fast.c b/third_party/libwebrtc/common_audio/signal_processing/downsample_fast.c new file mode 100644 index 0000000000..80fdc58a49 --- /dev/null +++ b/third_party/libwebrtc/common_audio/signal_processing/downsample_fast.c @@ -0,0 +1,65 @@ +/* + * Copyright (c) 2012 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. + */ + +#include "common_audio/signal_processing/include/signal_processing_library.h" + +#include "rtc_base/checks.h" +#include "rtc_base/sanitizer.h" + +// TODO(Bjornv): Change the function parameter order to WebRTC code style. +// C version of WebRtcSpl_DownsampleFast() for generic platforms. +int WebRtcSpl_DownsampleFastC(const int16_t* data_in, + size_t data_in_length, + int16_t* data_out, + size_t data_out_length, + const int16_t* __restrict coefficients, + size_t coefficients_length, + int factor, + size_t delay) { + int16_t* const original_data_out = data_out; + size_t i = 0; + size_t j = 0; + int32_t out_s32 = 0; + size_t endpos = delay + factor * (data_out_length - 1) + 1; + + // Return error if any of the running conditions doesn't meet. + if (data_out_length == 0 || coefficients_length == 0 + || data_in_length < endpos) { + return -1; + } + + rtc_MsanCheckInitialized(coefficients, sizeof(coefficients[0]), + coefficients_length); + + for (i = delay; i < endpos; i += factor) { + out_s32 = 2048; // Round value, 0.5 in Q12. + + for (j = 0; j < coefficients_length; j++) { + // Negative overflow is permitted here, because this is + // auto-regressive filters, and the state for each batch run is + // stored in the "negative" positions of the output vector. + rtc_MsanCheckInitialized(&data_in[(ptrdiff_t) i - (ptrdiff_t) j], + sizeof(data_in[0]), 1); + // out_s32 is in Q12 domain. + out_s32 += coefficients[j] * data_in[(ptrdiff_t) i - (ptrdiff_t) j]; + } + + out_s32 >>= 12; // Q0. + + // Saturate and store the output. + *data_out++ = WebRtcSpl_SatW32ToW16(out_s32); + } + + RTC_DCHECK_EQ(original_data_out + data_out_length, data_out); + rtc_MsanCheckInitialized(original_data_out, sizeof(original_data_out[0]), + data_out_length); + + return 0; +} |