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
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
|
#include <stdint.h>
#include <osmocom/core/bits.h>
/*! \addtogroup bits
* @{
*/
/*! \file bits.c
* \brief Osmocom bit level support code
*/
/*! \brief convert unpacked bits to packed bits, return length in bytes
* \param[out] out output buffer of packed bits
* \param[in] in input buffer of unpacked bits
* \param[in] num_bits number of bits
*/
int osmo_ubit2pbit(pbit_t *out, const ubit_t *in, unsigned int num_bits)
{
unsigned int i;
uint8_t curbyte = 0;
pbit_t *outptr = out;
for (i = 0; i < num_bits; i++) {
uint8_t bitnum = 7 - (i % 8);
curbyte |= (in[i] << bitnum);
if(i % 8 == 7){
*outptr++ = curbyte;
curbyte = 0;
}
}
/* we have a non-modulo-8 bitcount */
if (i % 8)
*outptr++ = curbyte;
return outptr - out;
}
/*! \brief convert packed bits to unpacked bits, return length in bytes
* \param[out] out output buffer of unpacked bits
* \param[in] in input buffer of packed bits
* \param[in] num_bits number of bits
*/
int osmo_pbit2ubit(ubit_t *out, const pbit_t *in, unsigned int num_bits)
{
unsigned int i;
ubit_t *cur = out;
ubit_t *limit = out + num_bits;
for (i = 0; i < (num_bits/8)+1; i++) {
pbit_t byte = in[i];
*cur++ = (byte >> 7) & 1;
if (cur >= limit)
break;
*cur++ = (byte >> 6) & 1;
if (cur >= limit)
break;
*cur++ = (byte >> 5) & 1;
if (cur >= limit)
break;
*cur++ = (byte >> 4) & 1;
if (cur >= limit)
break;
*cur++ = (byte >> 3) & 1;
if (cur >= limit)
break;
*cur++ = (byte >> 2) & 1;
if (cur >= limit)
break;
*cur++ = (byte >> 1) & 1;
if (cur >= limit)
break;
*cur++ = (byte >> 0) & 1;
if (cur >= limit)
break;
}
return cur - out;
}
/*! \brief convert unpacked bits to packed bits (extended options)
* \param[out] out output buffer of packed bits
* \param[in] out_ofs offset into output buffer
* \param[in] in input buffer of unpacked bits
* \param[in] in_ofs offset into input buffer
* \param[in] num_bits number of bits
* \param[in] lsb_mode Encode bits in LSB orde instead of MSB
* \returns length in bytes (max written offset of output buffer + 1)
*/
int osmo_ubit2pbit_ext(pbit_t *out, unsigned int out_ofs,
const ubit_t *in, unsigned int in_ofs,
unsigned int num_bits, int lsb_mode)
{
int i, op, bn;
for (i=0; i<num_bits; i++) {
op = out_ofs + i;
bn = lsb_mode ? (op&7) : (7-(op&7));
if (in[in_ofs+i])
out[op>>3] |= 1 << bn;
else
out[op>>3] &= ~(1 << bn);
}
return ((out_ofs + num_bits - 1) >> 3) + 1;
}
/*! \brief convert packed bits to unpacked bits (extended options)
* \param[out] out output buffer of unpacked bits
* \param[in] out_ofs offset into output buffer
* \param[in] in input buffer of packed bits
* \param[in] in_ofs offset into input buffer
* \param[in] num_bits number of bits
* \param[in] lsb_mode Encode bits in LSB orde instead of MSB
* \returns length in bytes (max written offset of output buffer + 1)
*/
int osmo_pbit2ubit_ext(ubit_t *out, unsigned int out_ofs,
const pbit_t *in, unsigned int in_ofs,
unsigned int num_bits, int lsb_mode)
{
int i, ip, bn;
for (i=0; i<num_bits; i++) {
ip = in_ofs + i;
bn = lsb_mode ? (ip&7) : (7-(ip&7));
out[out_ofs+i] = !!(in[ip>>3] & (1<<bn));
}
return out_ofs + num_bits;
}
/*! \brief generalized bit reversal function
* \param[in] x the 32bit value to be reversed
* \param[in] k the type of reversal requested
* \returns the reversed 32bit dword
*
* This function reverses the bit order within a 32bit word. Depending
* on "k", it either reverses all bits in a 32bit dword, or the bytes in
* the dword, or the bits in each byte of a dword, or simply swaps the
* two 16bit words in a dword. See Chapter 7 "Hackers Delight"
*/
uint32_t osmo_bit_reversal(uint32_t x, enum osmo_br_mode k)
{
if (k & 1) x = (x & 0x55555555) << 1 | (x & 0xAAAAAAAA) >> 1;
if (k & 2) x = (x & 0x33333333) << 2 | (x & 0xCCCCCCCC) >> 2;
if (k & 4) x = (x & 0x0F0F0F0F) << 4 | (x & 0xF0F0F0F0) >> 4;
if (k & 8) x = (x & 0x00FF00FF) << 8 | (x & 0xFF00FF00) >> 8;
if (k & 16) x = (x & 0x0000FFFF) << 16 | (x & 0xFFFF0000) >> 16;
return x;
}
/*! \brief reverse the bit-order in each byte of a dword
* \param[in] x 32bit input value
* \returns 32bit value where bits of each byte have been reversed
*
* See Chapter 7 "Hackers Delight"
*/
uint32_t osmo_revbytebits_32(uint32_t x)
{
x = (x & 0x55555555) << 1 | (x & 0xAAAAAAAA) >> 1;
x = (x & 0x33333333) << 2 | (x & 0xCCCCCCCC) >> 2;
x = (x & 0x0F0F0F0F) << 4 | (x & 0xF0F0F0F0) >> 4;
return x;
}
/*! \brief reverse the bit order in a byte
* \param[in] x 8bit input value
* \returns 8bit value where bits order has been reversed
*
* See Chapter 7 "Hackers Delight"
*/
uint32_t osmo_revbytebits_8(uint8_t x)
{
x = (x & 0x55) << 1 | (x & 0xAA) >> 1;
x = (x & 0x33) << 2 | (x & 0xCC) >> 2;
x = (x & 0x0F) << 4 | (x & 0xF0) >> 4;
return x;
}
/*! \brief reverse bit-order of each byte in a buffer
* \param buf buffer containing bytes to be bit-reversed
* \param[in] length of buffer in bytes
*
* This function reverses the bits in each byte of the buffer
*/
void osmo_revbytebits_buf(uint8_t *buf, int len)
{
unsigned int i;
unsigned int unaligned_cnt;
int len_remain = len;
unaligned_cnt = ((unsigned long)buf & 3);
for (i = 0; i < unaligned_cnt; i++) {
buf[i] = osmo_revbytebits_8(buf[i]);
len_remain--;
if (len_remain <= 0)
return;
}
for (i = unaligned_cnt; i + 3 < len; i += 4) {
uint32_t *cur = (uint32_t *) (buf + i);
*cur = osmo_revbytebits_32(*cur);
len_remain -= 4;
}
for (i = len - len_remain; i < len; i++) {
buf[i] = osmo_revbytebits_8(buf[i]);
len_remain--;
}
}
/*! @} */
|
