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 "rtc_base/checks.h"
12 #include "modules/audio_coding/codecs/isac/fix/source/codec.h"
13
14 // Autocorrelation function in fixed point.
15 // 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)16 int WebRtcIsacfix_AutocorrC(int32_t* __restrict r,
17 const int16_t* __restrict x,
18 int16_t N,
19 int16_t order,
20 int16_t* __restrict scale) {
21 int i = 0;
22 int j = 0;
23 int16_t scaling = 0;
24 int32_t sum = 0;
25 uint32_t temp = 0;
26 int64_t prod = 0;
27
28 // The ARM assembly code assumptoins.
29 RTC_DCHECK_EQ(0, N % 4);
30 RTC_DCHECK_GE(N, 8);
31
32 // Calculate r[0].
33 for (i = 0; i < N; i++) {
34 prod += x[i] * x[i];
35 }
36
37 // Calculate scaling (the value of shifting).
38 temp = (uint32_t)(prod >> 31);
39 if(temp == 0) {
40 scaling = 0;
41 } else {
42 scaling = 32 - WebRtcSpl_NormU32(temp);
43 }
44 r[0] = (int32_t)(prod >> scaling);
45
46 // Perform the actual correlation calculation.
47 for (i = 1; i < order + 1; i++) {
48 prod = 0;
49 for (j = 0; j < N - i; j++) {
50 prod += x[j] * x[i + j];
51 }
52 sum = (int32_t)(prod >> scaling);
53 r[i] = sum;
54 }
55
56 *scale = scaling;
57
58 return(order + 1);
59 }
60
61 static const int32_t kApUpperQ15[ALLPASSSECTIONS] = { 1137, 12537 };
62 static const int32_t kApLowerQ15[ALLPASSSECTIONS] = { 5059, 24379 };
63
64
AllpassFilterForDec32(int16_t * InOut16,const int32_t * APSectionFactors,int16_t lengthInOut,int32_t * FilterState)65 static void AllpassFilterForDec32(int16_t *InOut16, //Q0
66 const int32_t *APSectionFactors, //Q15
67 int16_t lengthInOut,
68 int32_t *FilterState) //Q16
69 {
70 int n, j;
71 int32_t a, b;
72
73 for (j=0; j<ALLPASSSECTIONS; j++) {
74 for (n=0;n<lengthInOut;n+=2){
75 a = WEBRTC_SPL_MUL_16_32_RSFT16(InOut16[n], APSectionFactors[j]); //Q0*Q31=Q31 shifted 16 gives Q15
76 a <<= 1; // Q15 -> Q16
77 b = WebRtcSpl_AddSatW32(a, FilterState[j]); //Q16+Q16=Q16
78 // |a| in Q15 (Q0*Q31=Q31 shifted 16 gives Q15).
79 a = WEBRTC_SPL_MUL_16_32_RSFT16(b >> 16, -APSectionFactors[j]);
80 // FilterState[j]: Q15<<1 + Q0<<16 = Q16 + Q16 = Q16
81 FilterState[j] = WebRtcSpl_AddSatW32(a << 1, (uint32_t)InOut16[n] << 16);
82 InOut16[n] = (int16_t)(b >> 16); // Save as Q0.
83 }
84 }
85 }
86
87
88
89
WebRtcIsacfix_DecimateAllpass32(const int16_t * in,int32_t * state_in,int16_t N,int16_t * out)90 void WebRtcIsacfix_DecimateAllpass32(const int16_t *in,
91 int32_t *state_in, /* array of size: 2*ALLPASSSECTIONS+1 */
92 int16_t N, /* number of input samples */
93 int16_t *out) /* array of size N/2 */
94 {
95 int n;
96 int16_t data_vec[PITCH_FRAME_LEN];
97
98 /* copy input */
99 memcpy(data_vec + 1, in, sizeof(int16_t) * (N - 1));
100
101 data_vec[0] = (int16_t)(state_in[2 * ALLPASSSECTIONS] >> 16); // z^-1 state.
102 state_in[2 * ALLPASSSECTIONS] = (uint32_t)in[N - 1] << 16;
103
104
105
106 AllpassFilterForDec32(data_vec+1, kApUpperQ15, N, state_in);
107 AllpassFilterForDec32(data_vec, kApLowerQ15, N, state_in+ALLPASSSECTIONS);
108
109 for (n=0;n<N/2;n++) {
110 out[n] = WebRtcSpl_AddSatW16(data_vec[2 * n], data_vec[2 * n + 1]);
111 }
112 }
113