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
12 /*
13 * This file contains implementations of the divisions
14 * WebRtcSpl_DivU32U16()
15 * WebRtcSpl_DivW32W16()
16 * WebRtcSpl_DivW32W16ResW16()
17 * WebRtcSpl_DivResultInQ31()
18 * WebRtcSpl_DivW32HiLow()
19 *
20 * The description header can be found in signal_processing_library.h
21 *
22 */
23
24 #include "webrtc/common_audio/signal_processing/include/signal_processing_library.h"
25
WebRtcSpl_DivU32U16(uint32_t num,uint16_t den)26 uint32_t WebRtcSpl_DivU32U16(uint32_t num, uint16_t den)
27 {
28 // Guard against division with 0
29 if (den != 0)
30 {
31 return (uint32_t)(num / den);
32 } else
33 {
34 return (uint32_t)0xFFFFFFFF;
35 }
36 }
37
WebRtcSpl_DivW32W16(int32_t num,int16_t den)38 int32_t WebRtcSpl_DivW32W16(int32_t num, int16_t den)
39 {
40 // Guard against division with 0
41 if (den != 0)
42 {
43 return (int32_t)(num / den);
44 } else
45 {
46 return (int32_t)0x7FFFFFFF;
47 }
48 }
49
WebRtcSpl_DivW32W16ResW16(int32_t num,int16_t den)50 int16_t WebRtcSpl_DivW32W16ResW16(int32_t num, int16_t den)
51 {
52 // Guard against division with 0
53 if (den != 0)
54 {
55 return (int16_t)(num / den);
56 } else
57 {
58 return (int16_t)0x7FFF;
59 }
60 }
61
WebRtcSpl_DivResultInQ31(int32_t num,int32_t den)62 int32_t WebRtcSpl_DivResultInQ31(int32_t num, int32_t den)
63 {
64 int32_t L_num = num;
65 int32_t L_den = den;
66 int32_t div = 0;
67 int k = 31;
68 int change_sign = 0;
69
70 if (num == 0)
71 return 0;
72
73 if (num < 0)
74 {
75 change_sign++;
76 L_num = -num;
77 }
78 if (den < 0)
79 {
80 change_sign++;
81 L_den = -den;
82 }
83 while (k--)
84 {
85 div <<= 1;
86 L_num <<= 1;
87 if (L_num >= L_den)
88 {
89 L_num -= L_den;
90 div++;
91 }
92 }
93 if (change_sign == 1)
94 {
95 div = -div;
96 }
97 return div;
98 }
99
WebRtcSpl_DivW32HiLow(int32_t num,int16_t den_hi,int16_t den_low)100 int32_t WebRtcSpl_DivW32HiLow(int32_t num, int16_t den_hi, int16_t den_low)
101 {
102 int16_t approx, tmp_hi, tmp_low, num_hi, num_low;
103 int32_t tmpW32;
104
105 approx = (int16_t)WebRtcSpl_DivW32W16((int32_t)0x1FFFFFFF, den_hi);
106 // result in Q14 (Note: 3FFFFFFF = 0.5 in Q30)
107
108 // tmpW32 = 1/den = approx * (2.0 - den * approx) (in Q30)
109 tmpW32 = (den_hi * approx << 1) + ((den_low * approx >> 15) << 1);
110 // tmpW32 = den * approx
111
112 tmpW32 = (int32_t)0x7fffffffL - tmpW32; // result in Q30 (tmpW32 = 2.0-(den*approx))
113
114 // Store tmpW32 in hi and low format
115 tmp_hi = (int16_t)(tmpW32 >> 16);
116 tmp_low = (int16_t)((tmpW32 - ((int32_t)tmp_hi << 16)) >> 1);
117
118 // tmpW32 = 1/den in Q29
119 tmpW32 = (tmp_hi * approx + (tmp_low * approx >> 15)) << 1;
120
121 // 1/den in hi and low format
122 tmp_hi = (int16_t)(tmpW32 >> 16);
123 tmp_low = (int16_t)((tmpW32 - ((int32_t)tmp_hi << 16)) >> 1);
124
125 // Store num in hi and low format
126 num_hi = (int16_t)(num >> 16);
127 num_low = (int16_t)((num - ((int32_t)num_hi << 16)) >> 1);
128
129 // num * (1/den) by 32 bit multiplication (result in Q28)
130
131 tmpW32 = num_hi * tmp_hi + (num_hi * tmp_low >> 15) +
132 (num_low * tmp_hi >> 15);
133
134 // Put result in Q31 (convert from Q28)
135 tmpW32 = WEBRTC_SPL_LSHIFT_W32(tmpW32, 3);
136
137 return tmpW32;
138 }
139