36e1ad9b5d
According to project structure discussed with Andrew. We want to flatten out the hierarchy and minimize the number of GYP files. No changes at all are being made in the source files; they are just moved. The only modified files are the GYP file and Android.mk Kevin: I updated relative paths in Android.mk so please verify it is correct, since I don't know how to build that. Review URL: http://webrtc-codereview.appspot.com/256006 git-svn-id: http://webrtc.googlecode.com/svn/trunk@894 4adac7df-926f-26a2-2b94-8c16560cd09d
83 lines
3.0 KiB
C
83 lines
3.0 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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iLBC Speech Coder ANSI-C Source Code
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WebRtcIlbcfix_Chebyshev.c
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******************************************************************/
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#include "defines.h"
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#include "constants.h"
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/*------------------------------------------------------------------*
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* Calculate the Chevyshev polynomial series
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* F(w) = 2*exp(-j5w)*C(x)
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* C(x) = (T_0(x) + f(1)T_1(x) + ... + f(4)T_1(x) + f(5)/2)
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* T_i(x) is the i:th order Chebyshev polynomial
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*------------------------------------------------------------------*/
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WebRtc_Word16 WebRtcIlbcfix_Chebyshev(
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/* (o) Result of C(x) */
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WebRtc_Word16 x, /* (i) Value to the Chevyshev polynomial */
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WebRtc_Word16 *f /* (i) The coefficients in the polynomial */
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) {
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WebRtc_Word16 b1_high, b1_low; /* Use the high, low format to increase the accuracy */
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WebRtc_Word32 b2;
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WebRtc_Word32 tmp1W32;
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WebRtc_Word32 tmp2W32;
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int i;
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b2 = (WebRtc_Word32)0x1000000; /* b2 = 1.0 (Q23) */
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/* Calculate b1 = 2*x + f[1] */
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tmp1W32 = WEBRTC_SPL_LSHIFT_W32((WebRtc_Word32)x, 10);
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tmp1W32 += WEBRTC_SPL_LSHIFT_W32((WebRtc_Word32)f[1], 14);
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for (i = 2; i < 5; i++) {
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tmp2W32 = tmp1W32;
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/* Split b1 (in tmp1W32) into a high and low part */
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b1_high = (WebRtc_Word16)WEBRTC_SPL_RSHIFT_W32(tmp1W32, 16);
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b1_low = (WebRtc_Word16)WEBRTC_SPL_RSHIFT_W32(tmp1W32-WEBRTC_SPL_LSHIFT_W32(((WebRtc_Word32)b1_high),16), 1);
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/* Calculate 2*x*b1-b2+f[i] */
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tmp1W32 = WEBRTC_SPL_LSHIFT_W32( (WEBRTC_SPL_MUL_16_16(b1_high, x) +
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WEBRTC_SPL_MUL_16_16_RSFT(b1_low, x, 15)), 2);
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tmp1W32 -= b2;
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tmp1W32 += WEBRTC_SPL_LSHIFT_W32((WebRtc_Word32)f[i], 14);
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/* Update b2 for next round */
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b2 = tmp2W32;
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}
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/* Split b1 (in tmp1W32) into a high and low part */
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b1_high = (WebRtc_Word16)WEBRTC_SPL_RSHIFT_W32(tmp1W32, 16);
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b1_low = (WebRtc_Word16)WEBRTC_SPL_RSHIFT_W32(tmp1W32-WEBRTC_SPL_LSHIFT_W32(((WebRtc_Word32)b1_high),16), 1);
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/* tmp1W32 = x*b1 - b2 + f[i]/2 */
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tmp1W32 = WEBRTC_SPL_LSHIFT_W32(WEBRTC_SPL_MUL_16_16(b1_high, x), 1) +
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WEBRTC_SPL_LSHIFT_W32(WEBRTC_SPL_MUL_16_16_RSFT(b1_low, x, 15), 1);
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tmp1W32 -= b2;
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tmp1W32 += WEBRTC_SPL_LSHIFT_W32((WebRtc_Word32)f[i], 13);
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/* Handle overflows and set to maximum or minimum WebRtc_Word16 instead */
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if (tmp1W32>((WebRtc_Word32)33553408)) {
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return(WEBRTC_SPL_WORD16_MAX);
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} else if (tmp1W32<((WebRtc_Word32)-33554432)) {
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return(WEBRTC_SPL_WORD16_MIN);
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} else {
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return((WebRtc_Word16)WEBRTC_SPL_RSHIFT_W32(tmp1W32, 10));
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}
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}
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