mirror of
https://github.com/oxen-io/session-android.git
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144 lines
3.6 KiB
C
144 lines
3.6 KiB
C
/*
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* Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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/*
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* This file contains implementations of the divisions
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* WebRtcSpl_DivU32U16()
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* WebRtcSpl_DivW32W16()
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* WebRtcSpl_DivW32W16ResW16()
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* WebRtcSpl_DivResultInQ31()
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* WebRtcSpl_DivW32HiLow()
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*
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* The description header can be found in signal_processing_library.h
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*
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*/
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#include "webrtc/common_audio/signal_processing/include/signal_processing_library.h"
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uint32_t WebRtcSpl_DivU32U16(uint32_t num, uint16_t den)
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{
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// Guard against division with 0
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if (den != 0)
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{
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return (uint32_t)(num / den);
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} else
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{
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return (uint32_t)0xFFFFFFFF;
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}
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}
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int32_t WebRtcSpl_DivW32W16(int32_t num, int16_t den)
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{
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// Guard against division with 0
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if (den != 0)
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{
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return (int32_t)(num / den);
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} else
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{
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return (int32_t)0x7FFFFFFF;
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}
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}
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int16_t WebRtcSpl_DivW32W16ResW16(int32_t num, int16_t den)
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{
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// Guard against division with 0
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if (den != 0)
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{
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return (int16_t)(num / den);
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} else
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{
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return (int16_t)0x7FFF;
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}
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}
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int32_t WebRtcSpl_DivResultInQ31(int32_t num, int32_t den)
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{
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int32_t L_num = num;
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int32_t L_den = den;
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int32_t div = 0;
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int k = 31;
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int change_sign = 0;
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if (num == 0)
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return 0;
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if (num < 0)
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{
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change_sign++;
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L_num = -num;
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}
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if (den < 0)
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{
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change_sign++;
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L_den = -den;
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}
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while (k--)
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{
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div <<= 1;
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L_num <<= 1;
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if (L_num >= L_den)
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{
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L_num -= L_den;
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div++;
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}
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}
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if (change_sign == 1)
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{
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div = -div;
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}
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return div;
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}
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int32_t WebRtcSpl_DivW32HiLow(int32_t num, int16_t den_hi, int16_t den_low)
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{
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int16_t approx, tmp_hi, tmp_low, num_hi, num_low;
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int32_t tmpW32;
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approx = (int16_t)WebRtcSpl_DivW32W16((int32_t)0x1FFFFFFF, den_hi);
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// result in Q14 (Note: 3FFFFFFF = 0.5 in Q30)
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// tmpW32 = 1/den = approx * (2.0 - den * approx) (in Q30)
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tmpW32 = (WEBRTC_SPL_MUL_16_16(den_hi, approx) << 1)
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+ ((WEBRTC_SPL_MUL_16_16(den_low, approx) >> 15) << 1);
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// tmpW32 = den * approx
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tmpW32 = (int32_t)0x7fffffffL - tmpW32; // result in Q30 (tmpW32 = 2.0-(den*approx))
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// Store tmpW32 in hi and low format
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tmp_hi = (int16_t)WEBRTC_SPL_RSHIFT_W32(tmpW32, 16);
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tmp_low = (int16_t)WEBRTC_SPL_RSHIFT_W32((tmpW32
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- WEBRTC_SPL_LSHIFT_W32((int32_t)tmp_hi, 16)), 1);
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// tmpW32 = 1/den in Q29
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tmpW32 = ((WEBRTC_SPL_MUL_16_16(tmp_hi, approx) + (WEBRTC_SPL_MUL_16_16(tmp_low, approx)
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>> 15)) << 1);
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// 1/den in hi and low format
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tmp_hi = (int16_t)WEBRTC_SPL_RSHIFT_W32(tmpW32, 16);
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tmp_low = (int16_t)WEBRTC_SPL_RSHIFT_W32((tmpW32
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- WEBRTC_SPL_LSHIFT_W32((int32_t)tmp_hi, 16)), 1);
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// Store num in hi and low format
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num_hi = (int16_t)WEBRTC_SPL_RSHIFT_W32(num, 16);
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num_low = (int16_t)WEBRTC_SPL_RSHIFT_W32((num
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- WEBRTC_SPL_LSHIFT_W32((int32_t)num_hi, 16)), 1);
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// num * (1/den) by 32 bit multiplication (result in Q28)
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tmpW32 = (WEBRTC_SPL_MUL_16_16(num_hi, tmp_hi) + (WEBRTC_SPL_MUL_16_16(num_hi, tmp_low)
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>> 15) + (WEBRTC_SPL_MUL_16_16(num_low, tmp_hi) >> 15));
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// Put result in Q31 (convert from Q28)
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tmpW32 = WEBRTC_SPL_LSHIFT_W32(tmpW32, 3);
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return tmpW32;
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}
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