-
Notifications
You must be signed in to change notification settings - Fork 20
Expand file tree
/
Copy pathdspfunc.c
More file actions
181 lines (148 loc) · 7.9 KB
/
Copy pathdspfunc.c
File metadata and controls
181 lines (148 loc) · 7.9 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
/*
ITU-T G.729A Speech Coder ANSI-C Source Code
Version 1.1 Last modified: September 1996
Copyright (c) 1996,
AT&T, France Telecom, NTT, Universite de Sherbrooke, Lucent Technologies
All rights reserved.
*/
#include "typedef.h"
#include "basic_op.h"
#include "ld8a.h"
#include "tab_ld8a.h"
/*___________________________________________________________________________
| |
| Function Name : Pow2() |
| |
| L_x = pow(2.0, exponent.fraction) |
|---------------------------------------------------------------------------|
| Algorithm: |
| |
| The function Pow2(L_x) is approximated by a table and linear |
| interpolation. |
| |
| 1- i = bit10-b15 of fraction, 0 <= i <= 31 |
| 2- a = bit0-b9 of fraction |
| 3- L_x = tabpow[i]<<16 - (tabpow[i] - tabpow[i+1]) * a * 2 |
| 4- L_x = L_x >> (30-exponent) (with rounding) |
|___________________________________________________________________________|
*/
Word32 Pow2( /* (o) Q0 : result (range: 0<=val<=0x7fffffff) */
Word16 exponent, /* (i) Q0 : Integer part. (range: 0<=val<=30) */
Word16 fraction /* (i) Q15 : Fractional part. (range: 0.0<=val<1.0) */
)
{
Word16 exp, i, a, tmp;
Word32 L_x;
L_x = L_mult(fraction, 32); /* L_x = fraction<<6 */
i = extract_h(L_x); /* Extract b10-b15 of fraction */
L_x = L_shr(L_x, 1);
a = extract_l(L_x); /* Extract b0-b9 of fraction */
a = a & (Word16)0x7fff;
L_x = L_deposit_h(tabpow[i]); /* tabpow[i] << 16 */
tmp = sub(tabpow[i], tabpow[i+1]); /* tabpow[i] - tabpow[i+1] */
L_x = L_msu(L_x, tmp, a); /* L_x -= tmp*a*2 */
exp = sub(30, exponent);
L_x = L_shr_r(L_x, exp);
return(L_x);
}
/*___________________________________________________________________________
| |
| Function Name : Log2() |
| |
| Compute log2(L_x). |
| L_x is positive. |
| |
| if L_x is negative or zero, result is 0. |
|---------------------------------------------------------------------------|
| Algorithm: |
| |
| The function Log2(L_x) is approximated by a table and linear |
| interpolation. |
| |
| 1- Normalization of L_x. |
| 2- exponent = 30-exponent |
| 3- i = bit25-b31 of L_x, 32 <= i <= 63 ->because of normalization. |
| 4- a = bit10-b24 |
| 5- i -=32 |
| 6- fraction = tablog[i]<<16 - (tablog[i] - tablog[i+1]) * a * 2 |
|___________________________________________________________________________|
*/
void Log2(
Word32 L_x, /* (i) Q0 : input value */
Word16 *exponent, /* (o) Q0 : Integer part of Log2. (range: 0<=val<=30) */
Word16 *fraction /* (o) Q15: Fractional part of Log2. (range: 0<=val<1) */
)
{
Word16 exp, i, a, tmp;
Word32 L_y;
if( L_x <= (Word32)0 )
{
*exponent = 0;
*fraction = 0;
return;
}
exp = norm_l(L_x);
L_x = L_shl(L_x, exp ); /* L_x is normalized */
*exponent = sub(30, exp);
L_x = L_shr(L_x, 9);
i = extract_h(L_x); /* Extract b25-b31 */
L_x = L_shr(L_x, 1);
a = extract_l(L_x); /* Extract b10-b24 of fraction */
a = a & (Word16)0x7fff;
i = sub(i, 32);
L_y = L_deposit_h(tablog[i]); /* tablog[i] << 16 */
tmp = sub(tablog[i], tablog[i+1]); /* tablog[i] - tablog[i+1] */
L_y = L_msu(L_y, tmp, a); /* L_y -= tmp*a*2 */
*fraction = extract_h( L_y);
return;
}
/*___________________________________________________________________________
| |
| Function Name : Inv_sqrt |
| |
| Compute 1/sqrt(L_x). |
| L_x is positive. |
| |
| if L_x is negative or zero, result is 1 (3fff ffff). |
|---------------------------------------------------------------------------|
| Algorithm: |
| |
| The function 1/sqrt(L_x) is approximated by a table and linear |
| interpolation. |
| |
| 1- Normalization of L_x. |
| 2- If (30-exponent) is even then shift right once. |
| 3- exponent = (30-exponent)/2 +1 |
| 4- i = bit25-b31 of L_x, 16 <= i <= 63 ->because of normalization. |
| 5- a = bit10-b24 |
| 6- i -=16 |
| 7- L_y = tabsqr[i]<<16 - (tabsqr[i] - tabsqr[i+1]) * a * 2 |
| 8- L_y >>= exponent |
|___________________________________________________________________________|
*/
Word32 Inv_sqrt( /* (o) Q30 : output value (range: 0<=val<1) */
Word32 L_x /* (i) Q0 : input value (range: 0<=val<=7fffffff) */
)
{
Word16 exp, i, a, tmp;
Word32 L_y;
if( L_x <= (Word32)0) return ( (Word32)0x3fffffffL);
exp = norm_l(L_x);
L_x = L_shl(L_x, exp ); /* L_x is normalize */
exp = sub(30, exp);
if( (exp & 1) == 0 ) /* If exponent even -> shift right */
L_x = L_shr(L_x, 1);
exp = shr(exp, 1);
exp = add(exp, 1);
L_x = L_shr(L_x, 9);
i = extract_h(L_x); /* Extract b25-b31 */
L_x = L_shr(L_x, 1);
a = extract_l(L_x); /* Extract b10-b24 */
a = a & (Word16)0x7fff;
i = sub(i, 16);
L_y = L_deposit_h(tabsqr[i]); /* tabsqr[i] << 16 */
tmp = sub(tabsqr[i], tabsqr[i+1]); /* tabsqr[i] - tabsqr[i+1]) */
L_y = L_msu(L_y, tmp, a); /* L_y -= tmp*a*2 */
L_y = L_shr(L_y, exp); /* denormalization */
return(L_y);
}