mirror of
https://github.com/mollyim/webrtc.git
synced 2025-05-13 22:00:47 +01:00
06c2aa9f7b
WebRTC internal code should always use include paths that start from the root of the project and that clearly identify the header file. This allows 'gn check' to actually keep dependencies under control because 'gn check' cannot enforce anything if the include path is not fully qualified (starting from the root of the project). Bug: webrtc:8815 Change-Id: I36f01784fa5f5b77eefc02db479b1f7f6ee1a8c3 Reviewed-on: https://webrtc-review.googlesource.com/46263 Reviewed-by: Karl Wiberg <kwiberg@webrtc.org> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org> Cr-Commit-Position: refs/heads/master@{#21871}
74 lines
2.4 KiB
C
74 lines
2.4 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.
|
|
*/
|
|
|
|
/******************************************************************
|
|
|
|
iLBC Speech Coder ANSI-C Source Code
|
|
|
|
WebRtcIlbcfix_Chebyshev.c
|
|
|
|
******************************************************************/
|
|
|
|
#include "modules/audio_coding/codecs/ilbc/defines.h"
|
|
#include "modules/audio_coding/codecs/ilbc/constants.h"
|
|
|
|
/*------------------------------------------------------------------*
|
|
* Calculate the Chevyshev polynomial series
|
|
* F(w) = 2*exp(-j5w)*C(x)
|
|
* C(x) = (T_0(x) + f(1)T_1(x) + ... + f(4)T_1(x) + f(5)/2)
|
|
* T_i(x) is the i:th order Chebyshev polynomial
|
|
*------------------------------------------------------------------*/
|
|
|
|
int16_t WebRtcIlbcfix_Chebyshev(
|
|
/* (o) Result of C(x) */
|
|
int16_t x, /* (i) Value to the Chevyshev polynomial */
|
|
int16_t *f /* (i) The coefficients in the polynomial */
|
|
) {
|
|
int16_t b1_high, b1_low; /* Use the high, low format to increase the accuracy */
|
|
int32_t b2;
|
|
int32_t tmp1W32;
|
|
int32_t tmp2W32;
|
|
int i;
|
|
|
|
b2 = (int32_t)0x1000000; /* b2 = 1.0 (Q23) */
|
|
/* Calculate b1 = 2*x + f[1] */
|
|
tmp1W32 = (x << 10) + (f[1] << 14);
|
|
|
|
for (i = 2; i < 5; i++) {
|
|
tmp2W32 = tmp1W32;
|
|
|
|
/* Split b1 (in tmp1W32) into a high and low part */
|
|
b1_high = (int16_t)(tmp1W32 >> 16);
|
|
b1_low = (int16_t)((tmp1W32 - ((int32_t)b1_high << 16)) >> 1);
|
|
|
|
/* Calculate 2*x*b1-b2+f[i] */
|
|
tmp1W32 = ((b1_high * x + ((b1_low * x) >> 15)) << 2) - b2 + (f[i] << 14);
|
|
|
|
/* Update b2 for next round */
|
|
b2 = tmp2W32;
|
|
}
|
|
|
|
/* Split b1 (in tmp1W32) into a high and low part */
|
|
b1_high = (int16_t)(tmp1W32 >> 16);
|
|
b1_low = (int16_t)((tmp1W32 - ((int32_t)b1_high << 16)) >> 1);
|
|
|
|
/* tmp1W32 = x*b1 - b2 + f[i]/2 */
|
|
tmp1W32 = ((b1_high * x) << 1) + (((b1_low * x) >> 15) << 1) -
|
|
b2 + (f[i] << 13);
|
|
|
|
/* Handle overflows and set to maximum or minimum int16_t instead */
|
|
if (tmp1W32>((int32_t)33553408)) {
|
|
return(WEBRTC_SPL_WORD16_MAX);
|
|
} else if (tmp1W32<((int32_t)-33554432)) {
|
|
return(WEBRTC_SPL_WORD16_MIN);
|
|
} else {
|
|
return (int16_t)(tmp1W32 >> 10);
|
|
}
|
|
}
|