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
182
183
184
185
186
187
188
189
190
191
192
193
|
/*
* Viterbi decoder
*
* Copyright (C) 2013, 2014 Thomas Tsou <tom@tsou.cc>
*
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <stdint.h>
#include <string.h>
/* Add-Compare-Select (ACS-Butterfly)
* Compute 4 accumulated path metrics and 4 path selections. Note that path
* selections are store as -1 and 0 rather than 0 and 1. This is to match
* the output format of the SSE packed compare instruction 'pmaxuw'.
*/
static void acs_butterfly(int state, int num_states,
int16_t metric, int16_t *sum,
int16_t *new_sum, int16_t *path)
{
int state0, state1;
int sum0, sum1, sum2, sum3;
state0 = *(sum + (2 * state + 0));
state1 = *(sum + (2 * state + 1));
sum0 = state0 + metric;
sum1 = state1 - metric;
sum2 = state0 - metric;
sum3 = state1 + metric;
if (sum0 >= sum1) {
*new_sum = sum0;
*path = -1;
} else {
*new_sum = sum1;
*path = 0;
}
if (sum2 >= sum3) {
*(new_sum + num_states / 2) = sum2;
*(path + num_states / 2) = -1;
} else {
*(new_sum + num_states / 2) = sum3;
*(path + num_states / 2) = 0;
}
}
/* Branch metrics unit N=2 */
static void gen_branch_metrics_n2(int num_states, const int8_t *seq,
const int16_t *out, int16_t *metrics)
{
int i;
for (i = 0; i < num_states / 2; i++) {
metrics[i] = seq[0] * out[2 * i + 0] +
seq[1] * out[2 * i + 1];
}
}
/* Branch metrics unit N=3 */
static void gen_branch_metrics_n3(int num_states, const int8_t *seq,
const int16_t *out, int16_t *metrics)
{
int i;
for (i = 0; i < num_states / 2; i++) {
metrics[i] = seq[0] * out[4 * i + 0] +
seq[1] * out[4 * i + 1] +
seq[2] * out[4 * i + 2];
}
}
/* Branch metrics unit N=4 */
static void gen_branch_metrics_n4(int num_states, const int8_t *seq,
const int16_t *out, int16_t *metrics)
{
int i;
for (i = 0; i < num_states / 2; i++) {
metrics[i] = seq[0] * out[4 * i + 0] +
seq[1] * out[4 * i + 1] +
seq[2] * out[4 * i + 2] +
seq[3] * out[4 * i + 3];
}
}
/* Path metric unit */
static void gen_path_metrics(int num_states, int16_t *sums,
int16_t *metrics, int16_t *paths, int norm)
{
int i;
int16_t min;
int16_t new_sums[num_states];
for (i = 0; i < num_states / 2; i++)
acs_butterfly(i, num_states, metrics[i],
sums, &new_sums[i], &paths[i]);
if (norm) {
min = new_sums[0];
for (i = 1; i < num_states; i++)
if (new_sums[i] < min)
min = new_sums[i];
for (i = 0; i < num_states; i++)
new_sums[i] -= min;
}
memcpy(sums, new_sums, num_states * sizeof(int16_t));
}
/* 16-state branch-path metrics units (K=5) */
__attribute__ ((visibility("hidden")))
void osmo_conv_gen_metrics_k5_n2(const int8_t *seq, const int16_t *out,
int16_t *sums, int16_t *paths, int norm)
{
int16_t metrics[8];
gen_branch_metrics_n2(16, seq, out, metrics);
gen_path_metrics(16, sums, metrics, paths, norm);
}
__attribute__ ((visibility("hidden")))
void osmo_conv_gen_metrics_k5_n3(const int8_t *seq, const int16_t *out,
int16_t *sums, int16_t *paths, int norm)
{
int16_t metrics[8];
gen_branch_metrics_n3(16, seq, out, metrics);
gen_path_metrics(16, sums, metrics, paths, norm);
}
__attribute__ ((visibility("hidden")))
void osmo_conv_gen_metrics_k5_n4(const int8_t *seq, const int16_t *out,
int16_t *sums, int16_t *paths, int norm)
{
int16_t metrics[8];
gen_branch_metrics_n4(16, seq, out, metrics);
gen_path_metrics(16, sums, metrics, paths, norm);
}
/* 64-state branch-path metrics units (K=7) */
__attribute__ ((visibility("hidden")))
void osmo_conv_gen_metrics_k7_n2(const int8_t *seq, const int16_t *out,
int16_t *sums, int16_t *paths, int norm)
{
int16_t metrics[32];
gen_branch_metrics_n2(64, seq, out, metrics);
gen_path_metrics(64, sums, metrics, paths, norm);
}
__attribute__ ((visibility("hidden")))
void osmo_conv_gen_metrics_k7_n3(const int8_t *seq, const int16_t *out,
int16_t *sums, int16_t *paths, int norm)
{
int16_t metrics[32];
gen_branch_metrics_n3(64, seq, out, metrics);
gen_path_metrics(64, sums, metrics, paths, norm);
}
__attribute__ ((visibility("hidden")))
void osmo_conv_gen_metrics_k7_n4(const int8_t *seq, const int16_t *out,
int16_t *sums, int16_t *paths, int norm)
{
int16_t metrics[32];
gen_branch_metrics_n4(64, seq, out, metrics);
gen_path_metrics(64, sums, metrics, paths, norm);
}
|
