145 lines
3.9 KiB
C
145 lines
3.9 KiB
C
/*
|
|
* 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 implementations of the divisions
|
|
* WebRtcSpl_DivU32U16()
|
|
* WebRtcSpl_DivW32W16()
|
|
* WebRtcSpl_DivW32W16ResW16()
|
|
* WebRtcSpl_DivResultInQ31()
|
|
* WebRtcSpl_DivW32HiLow()
|
|
*
|
|
* The description header can be found in signal_processing_library.h
|
|
*
|
|
*/
|
|
|
|
#include "signal_processing_library.h"
|
|
|
|
WebRtc_UWord32 WebRtcSpl_DivU32U16(WebRtc_UWord32 num, WebRtc_UWord16 den)
|
|
{
|
|
// Guard against division with 0
|
|
if (den != 0)
|
|
{
|
|
return (WebRtc_UWord32)(num / den);
|
|
} else
|
|
{
|
|
return (WebRtc_UWord32)0xFFFFFFFF;
|
|
}
|
|
}
|
|
|
|
WebRtc_Word32 WebRtcSpl_DivW32W16(WebRtc_Word32 num, WebRtc_Word16 den)
|
|
{
|
|
// Guard against division with 0
|
|
if (den != 0)
|
|
{
|
|
return (WebRtc_Word32)(num / den);
|
|
} else
|
|
{
|
|
return (WebRtc_Word32)0x7FFFFFFF;
|
|
}
|
|
}
|
|
|
|
WebRtc_Word16 WebRtcSpl_DivW32W16ResW16(WebRtc_Word32 num, WebRtc_Word16 den)
|
|
{
|
|
// Guard against division with 0
|
|
if (den != 0)
|
|
{
|
|
return (WebRtc_Word16)(num / den);
|
|
} else
|
|
{
|
|
return (WebRtc_Word16)0x7FFF;
|
|
}
|
|
}
|
|
|
|
WebRtc_Word32 WebRtcSpl_DivResultInQ31(WebRtc_Word32 num, WebRtc_Word32 den)
|
|
{
|
|
WebRtc_Word32 L_num = num;
|
|
WebRtc_Word32 L_den = den;
|
|
WebRtc_Word32 div = 0;
|
|
int k = 31;
|
|
int change_sign = 0;
|
|
|
|
if (num == 0)
|
|
return 0;
|
|
|
|
if (num < 0)
|
|
{
|
|
change_sign++;
|
|
L_num = -num;
|
|
}
|
|
if (den < 0)
|
|
{
|
|
change_sign++;
|
|
L_den = -den;
|
|
}
|
|
while (k--)
|
|
{
|
|
div <<= 1;
|
|
L_num <<= 1;
|
|
if (L_num >= L_den)
|
|
{
|
|
L_num -= L_den;
|
|
div++;
|
|
}
|
|
}
|
|
if (change_sign == 1)
|
|
{
|
|
div = -div;
|
|
}
|
|
return div;
|
|
}
|
|
|
|
WebRtc_Word32 WebRtcSpl_DivW32HiLow(WebRtc_Word32 num, WebRtc_Word16 den_hi,
|
|
WebRtc_Word16 den_low)
|
|
{
|
|
WebRtc_Word16 approx, tmp_hi, tmp_low, num_hi, num_low;
|
|
WebRtc_Word32 tmpW32;
|
|
|
|
approx = (WebRtc_Word16)WebRtcSpl_DivW32W16((WebRtc_Word32)0x1FFFFFFF, den_hi);
|
|
// result in Q14 (Note: 3FFFFFFF = 0.5 in Q30)
|
|
|
|
// tmpW32 = 1/den = approx * (2.0 - den * approx) (in Q30)
|
|
tmpW32 = (WEBRTC_SPL_MUL_16_16(den_hi, approx) << 1)
|
|
+ ((WEBRTC_SPL_MUL_16_16(den_low, approx) >> 15) << 1);
|
|
// tmpW32 = den * approx
|
|
|
|
tmpW32 = (WebRtc_Word32)0x7fffffffL - tmpW32; // result in Q30 (tmpW32 = 2.0-(den*approx))
|
|
|
|
// Store tmpW32 in hi and low format
|
|
tmp_hi = (WebRtc_Word16)WEBRTC_SPL_RSHIFT_W32(tmpW32, 16);
|
|
tmp_low = (WebRtc_Word16)WEBRTC_SPL_RSHIFT_W32((tmpW32
|
|
- WEBRTC_SPL_LSHIFT_W32((WebRtc_Word32)tmp_hi, 16)), 1);
|
|
|
|
// tmpW32 = 1/den in Q29
|
|
tmpW32 = ((WEBRTC_SPL_MUL_16_16(tmp_hi, approx) + (WEBRTC_SPL_MUL_16_16(tmp_low, approx)
|
|
>> 15)) << 1);
|
|
|
|
// 1/den in hi and low format
|
|
tmp_hi = (WebRtc_Word16)WEBRTC_SPL_RSHIFT_W32(tmpW32, 16);
|
|
tmp_low = (WebRtc_Word16)WEBRTC_SPL_RSHIFT_W32((tmpW32
|
|
- WEBRTC_SPL_LSHIFT_W32((WebRtc_Word32)tmp_hi, 16)), 1);
|
|
|
|
// Store num in hi and low format
|
|
num_hi = (WebRtc_Word16)WEBRTC_SPL_RSHIFT_W32(num, 16);
|
|
num_low = (WebRtc_Word16)WEBRTC_SPL_RSHIFT_W32((num
|
|
- WEBRTC_SPL_LSHIFT_W32((WebRtc_Word32)num_hi, 16)), 1);
|
|
|
|
// num * (1/den) by 32 bit multiplication (result in Q28)
|
|
|
|
tmpW32 = (WEBRTC_SPL_MUL_16_16(num_hi, tmp_hi) + (WEBRTC_SPL_MUL_16_16(num_hi, tmp_low)
|
|
>> 15) + (WEBRTC_SPL_MUL_16_16(num_low, tmp_hi) >> 15));
|
|
|
|
// Put result in Q31 (convert from Q28)
|
|
tmpW32 = WEBRTC_SPL_LSHIFT_W32(tmpW32, 3);
|
|
|
|
return tmpW32;
|
|
}
|