1 /*
2 * Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10
11 #include <assert.h>
12
13 #include "webrtc/modules/audio_coding/codecs/isac/fix/source/codec.h"
14
15 // Autocorrelation function in fixed point.
16 // NOTE! Different from SPLIB-version in how it scales the signal.
WebRtcIsacfix_AutocorrC(int32_t * __restrict r,const int16_t * __restrict x,int16_t N,int16_t order,int16_t * __restrict scale)17 int WebRtcIsacfix_AutocorrC(int32_t* __restrict r,
18 const int16_t* __restrict x,
19 int16_t N,
20 int16_t order,
21 int16_t* __restrict scale) {
22 int i = 0;
23 int j = 0;
24 int16_t scaling = 0;
25 int32_t sum = 0;
26 uint32_t temp = 0;
27 int64_t prod = 0;
28
29 // The ARM assembly code assumptoins.
30 assert(N % 4 == 0);
31 assert(N >= 8);
32
33 // Calculate r[0].
34 for (i = 0; i < N; i++) {
35 prod += x[i] * x[i];
36 }
37
38 // Calculate scaling (the value of shifting).
39 temp = (uint32_t)(prod >> 31);
40 if(temp == 0) {
41 scaling = 0;
42 } else {
43 scaling = 32 - WebRtcSpl_NormU32(temp);
44 }
45 r[0] = (int32_t)(prod >> scaling);
46
47 // Perform the actual correlation calculation.
48 for (i = 1; i < order + 1; i++) {
49 prod = 0;
50 for (j = 0; j < N - i; j++) {
51 prod += x[j] * x[i + j];
52 }
53 sum = (int32_t)(prod >> scaling);
54 r[i] = sum;
55 }
56
57 *scale = scaling;
58
59 return(order + 1);
60 }
61
62 static const int32_t kApUpperQ15[ALLPASSSECTIONS] = { 1137, 12537 };
63 static const int32_t kApLowerQ15[ALLPASSSECTIONS] = { 5059, 24379 };
64
65
AllpassFilterForDec32(int16_t * InOut16,const int32_t * APSectionFactors,int16_t lengthInOut,int32_t * FilterState)66 static void AllpassFilterForDec32(int16_t *InOut16, //Q0
67 const int32_t *APSectionFactors, //Q15
68 int16_t lengthInOut,
69 int32_t *FilterState) //Q16
70 {
71 int n, j;
72 int32_t a, b;
73
74 for (j=0; j<ALLPASSSECTIONS; j++) {
75 for (n=0;n<lengthInOut;n+=2){
76 a = WEBRTC_SPL_MUL_16_32_RSFT16(InOut16[n], APSectionFactors[j]); //Q0*Q31=Q31 shifted 16 gives Q15
77 a <<= 1; // Q15 -> Q16
78 b = WebRtcSpl_AddSatW32(a, FilterState[j]); //Q16+Q16=Q16
79 // |a| in Q15 (Q0*Q31=Q31 shifted 16 gives Q15).
80 a = WEBRTC_SPL_MUL_16_32_RSFT16(b >> 16, -APSectionFactors[j]);
81 // FilterState[j]: Q15<<1 + Q0<<16 = Q16 + Q16 = Q16
82 FilterState[j] = WebRtcSpl_AddSatW32(a << 1, (uint32_t)InOut16[n] << 16);
83 InOut16[n] = (int16_t)(b >> 16); // Save as Q0.
84 }
85 }
86 }
87
88
89
90
WebRtcIsacfix_DecimateAllpass32(const int16_t * in,int32_t * state_in,int16_t N,int16_t * out)91 void WebRtcIsacfix_DecimateAllpass32(const int16_t *in,
92 int32_t *state_in, /* array of size: 2*ALLPASSSECTIONS+1 */
93 int16_t N, /* number of input samples */
94 int16_t *out) /* array of size N/2 */
95 {
96 int n;
97 int16_t data_vec[PITCH_FRAME_LEN];
98
99 /* copy input */
100 memcpy(data_vec + 1, in, sizeof(int16_t) * (N - 1));
101
102 data_vec[0] = (int16_t)(state_in[2 * ALLPASSSECTIONS] >> 16); // z^-1 state.
103 state_in[2 * ALLPASSSECTIONS] = (uint32_t)in[N - 1] << 16;
104
105
106
107 AllpassFilterForDec32(data_vec+1, kApUpperQ15, N, state_in);
108 AllpassFilterForDec32(data_vec, kApLowerQ15, N, state_in+ALLPASSSECTIONS);
109
110 for (n=0;n<N/2;n++) {
111 out[n] = WebRtcSpl_AddSatW16(data_vec[2 * n], data_vec[2 * n + 1]);
112 }
113 }
114