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bb547203bf
In order to eliminate the WebRTC Subtree mirror in Chromium, WebRTC is moving the content of the src/webrtc directory up to the src/ directory. NOPRESUBMIT=true NOTREECHECKS=true NOTRY=true TBR=tommi@webrtc.org Bug: chromium:611808 Change-Id: Iac59c5b51b950f174119565bac87955a7994bc38 Reviewed-on: https://webrtc-review.googlesource.com/1560 Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org> Reviewed-by: Henrik Kjellander <kjellander@webrtc.org> Cr-Commit-Position: refs/heads/master@{#19845}
82 lines
2 KiB
C
82 lines
2 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_GetLspPoly.c
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******************************************************************/
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#include "defines.h"
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/*----------------------------------------------------------------*
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* Construct the polynomials F1(z) and F2(z) from the LSP
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* (Computations are done in Q24)
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*
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* The expansion is performed using the following recursion:
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*
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* f[0] = 1;
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* tmp = -2.0 * lsp[0];
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* f[1] = tmp;
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* for (i=2; i<=5; i++) {
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* b = -2.0 * lsp[2*i-2];
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* f[i] = tmp*f[i-1] + 2.0*f[i-2];
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* for (j=i; j>=2; j--) {
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* f[j] = f[j] + tmp*f[j-1] + f[j-2];
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* }
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* f[i] = f[i] + tmp;
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* }
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*---------------------------------------------------------------*/
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void WebRtcIlbcfix_GetLspPoly(
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int16_t *lsp, /* (i) LSP in Q15 */
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int32_t *f) /* (o) polonymial in Q24 */
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{
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int32_t tmpW32;
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int i, j;
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int16_t high, low;
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int16_t *lspPtr;
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int32_t *fPtr;
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lspPtr = lsp;
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fPtr = f;
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/* f[0] = 1.0 (Q24) */
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(*fPtr) = (int32_t)16777216;
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fPtr++;
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(*fPtr) = WEBRTC_SPL_MUL((*lspPtr), -1024);
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fPtr++;
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lspPtr+=2;
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for(i=2; i<=5; i++)
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{
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(*fPtr) = fPtr[-2];
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for(j=i; j>1; j--)
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{
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/* Compute f[j] = f[j] + tmp*f[j-1] + f[j-2]; */
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high = (int16_t)(fPtr[-1] >> 16);
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low = (int16_t)((fPtr[-1] & 0xffff) >> 1);
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tmpW32 = 4 * high * *lspPtr + 4 * ((low * *lspPtr) >> 15);
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(*fPtr) += fPtr[-2];
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(*fPtr) -= tmpW32;
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fPtr--;
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}
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*fPtr -= *lspPtr * (1 << 10);
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fPtr+=i;
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lspPtr+=2;
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}
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return;
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}
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