f71785cd3b
Replaced trivial shift macro with >>. The actual implementation of the macro is simply >>. Affected codecs: * ilbc * isac/fix BUG=3348,3353 TESTED=locally on linux and trybots R=henrik.lundin@webrtc.org, kwiberg@webrtc.org Review URL: https://webrtc-codereview.appspot.com/23889004 git-svn-id: http://webrtc.googlecode.com/svn/trunk@7396 4adac7df-926f-26a2-2b94-8c16560cd09d
62 lines
1.8 KiB
C
62 lines
1.8 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_Lsf2Lsp.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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* conversion from lsf to lsp coefficients
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*---------------------------------------------------------------*/
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void WebRtcIlbcfix_Lsf2Lsp(
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int16_t *lsf, /* (i) lsf in Q13 values between 0 and pi */
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int16_t *lsp, /* (o) lsp in Q15 values between -1 and 1 */
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int16_t m /* (i) number of coefficients */
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) {
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int16_t i, k;
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int16_t diff; /* difference, which is used for the
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linear approximation (Q8) */
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int16_t freq; /* normalized frequency in Q15 (0..1) */
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int32_t tmpW32;
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for(i=0; i<m; i++)
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{
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freq = (int16_t)WEBRTC_SPL_MUL_16_16_RSFT(lsf[i], 20861, 15);
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/* 20861: 1.0/(2.0*PI) in Q17 */
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/*
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Upper 8 bits give the index k and
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Lower 8 bits give the difference, which needs
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to be approximated linearly
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*/
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k = freq >> 8;
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diff = (freq&0x00ff);
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/* Guard against getting outside table */
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if (k>63) {
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k = 63;
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}
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/* Calculate linear approximation */
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tmpW32 = WEBRTC_SPL_MUL_16_16(WebRtcIlbcfix_kCosDerivative[k], diff);
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lsp[i] = WebRtcIlbcfix_kCos[k]+(int16_t)(WEBRTC_SPL_RSHIFT_W32(tmpW32, 12));
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}
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return;
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}
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