Harald Welte | 468b643 | 2014-09-11 13:05:51 +0800 | [diff] [blame] | 1 | /* |
| 2 | * (C) 2011 by Harald Welte <laforge@gnumonks.org> |
| 3 | * (C) 2011 by Sylvain Munaut <tnt@246tNt.com> |
| 4 | * |
| 5 | * All Rights Reserved |
| 6 | * |
| 7 | * This program is free software; you can redistribute it and/or modify |
| 8 | * it under the terms of the GNU General Public License as published by |
| 9 | * the Free Software Foundation; either version 2 of the License, or |
| 10 | * (at your option) any later version. |
| 11 | * |
| 12 | * This program is distributed in the hope that it will be useful, |
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | * GNU General Public License for more details. |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License along |
| 18 | * with this program; if not, write to the Free Software Foundation, Inc., |
| 19 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | * |
| 21 | */ |
Harald Welte | 2230c13 | 2011-01-19 10:10:16 +0100 | [diff] [blame] | 22 | |
| 23 | #include <stdint.h> |
| 24 | |
Pablo Neira Ayuso | 8341934 | 2011-03-22 16:36:13 +0100 | [diff] [blame] | 25 | #include <osmocom/core/bits.h> |
Harald Welte | 2230c13 | 2011-01-19 10:10:16 +0100 | [diff] [blame] | 26 | |
Harald Welte | ba6988b | 2011-08-17 12:46:48 +0200 | [diff] [blame] | 27 | /*! \addtogroup bits |
| 28 | * @{ |
| 29 | */ |
| 30 | |
| 31 | /*! \file bits.c |
| 32 | * \brief Osmocom bit level support code |
| 33 | */ |
| 34 | |
| 35 | |
| 36 | /*! \brief convert unpacked bits to packed bits, return length in bytes |
| 37 | * \param[out] out output buffer of packed bits |
| 38 | * \param[in] in input buffer of unpacked bits |
| 39 | * \param[in] num_bits number of bits |
| 40 | */ |
Harald Welte | 2230c13 | 2011-01-19 10:10:16 +0100 | [diff] [blame] | 41 | int osmo_ubit2pbit(pbit_t *out, const ubit_t *in, unsigned int num_bits) |
| 42 | { |
| 43 | unsigned int i; |
| 44 | uint8_t curbyte = 0; |
| 45 | pbit_t *outptr = out; |
| 46 | |
| 47 | for (i = 0; i < num_bits; i++) { |
| 48 | uint8_t bitnum = 7 - (i % 8); |
| 49 | |
| 50 | curbyte |= (in[i] << bitnum); |
| 51 | |
Christian Vogel | c7f84e9 | 2011-01-22 22:48:37 +0100 | [diff] [blame] | 52 | if(i % 8 == 7){ |
Harald Welte | 2230c13 | 2011-01-19 10:10:16 +0100 | [diff] [blame] | 53 | *outptr++ = curbyte; |
| 54 | curbyte = 0; |
| 55 | } |
| 56 | } |
| 57 | /* we have a non-modulo-8 bitcount */ |
| 58 | if (i % 8) |
| 59 | *outptr++ = curbyte; |
| 60 | |
| 61 | return outptr - out; |
| 62 | } |
| 63 | |
Max | d8fb142 | 2016-04-06 16:13:00 +0200 | [diff] [blame] | 64 | /*! \brief convert unpacked bits to soft bits |
| 65 | * \param[out] out output buffer of soft bits |
| 66 | * \param[in] in input buffer of unpacked bits |
| 67 | * \param[in] num_bits number of bits |
| 68 | */ |
| 69 | void osmo_ubit2sbit(sbit_t *out, const ubit_t *in, unsigned int num_bits) |
| 70 | { |
| 71 | unsigned int i; |
| 72 | for (i = 0; i < num_bits; i++) |
| 73 | out[i] = in[i] ? -127 : 127; |
| 74 | } |
| 75 | |
| 76 | /*! \brief convert soft bits to unpacked bits |
| 77 | * \param[out] out output buffer of unpacked bits |
| 78 | * \param[in] in input buffer of soft bits |
| 79 | * \param[in] num_bits number of bits |
| 80 | */ |
| 81 | void osmo_sbit2ubit(ubit_t *out, const sbit_t *in, unsigned int num_bits) |
| 82 | { |
| 83 | unsigned int i; |
| 84 | for (i = 0; i < num_bits; i++) |
| 85 | out[i] = in[i] < 0; |
| 86 | } |
| 87 | |
Harald Welte | ba6988b | 2011-08-17 12:46:48 +0200 | [diff] [blame] | 88 | /*! \brief convert packed bits to unpacked bits, return length in bytes |
| 89 | * \param[out] out output buffer of unpacked bits |
| 90 | * \param[in] in input buffer of packed bits |
| 91 | * \param[in] num_bits number of bits |
| 92 | */ |
Harald Welte | 2230c13 | 2011-01-19 10:10:16 +0100 | [diff] [blame] | 93 | int osmo_pbit2ubit(ubit_t *out, const pbit_t *in, unsigned int num_bits) |
| 94 | { |
| 95 | unsigned int i; |
| 96 | ubit_t *cur = out; |
| 97 | ubit_t *limit = out + num_bits; |
| 98 | |
| 99 | for (i = 0; i < (num_bits/8)+1; i++) { |
| 100 | pbit_t byte = in[i]; |
| 101 | *cur++ = (byte >> 7) & 1; |
| 102 | if (cur >= limit) |
| 103 | break; |
| 104 | *cur++ = (byte >> 6) & 1; |
| 105 | if (cur >= limit) |
| 106 | break; |
| 107 | *cur++ = (byte >> 5) & 1; |
| 108 | if (cur >= limit) |
| 109 | break; |
| 110 | *cur++ = (byte >> 4) & 1; |
| 111 | if (cur >= limit) |
| 112 | break; |
| 113 | *cur++ = (byte >> 3) & 1; |
| 114 | if (cur >= limit) |
| 115 | break; |
| 116 | *cur++ = (byte >> 2) & 1; |
| 117 | if (cur >= limit) |
| 118 | break; |
| 119 | *cur++ = (byte >> 1) & 1; |
| 120 | if (cur >= limit) |
| 121 | break; |
| 122 | *cur++ = (byte >> 0) & 1; |
| 123 | if (cur >= limit) |
| 124 | break; |
| 125 | } |
| 126 | return cur - out; |
| 127 | } |
Sylvain Munaut | aeb1077 | 2011-01-21 12:22:30 +0100 | [diff] [blame] | 128 | |
Harald Welte | ba6988b | 2011-08-17 12:46:48 +0200 | [diff] [blame] | 129 | /*! \brief convert unpacked bits to packed bits (extended options) |
| 130 | * \param[out] out output buffer of packed bits |
| 131 | * \param[in] out_ofs offset into output buffer |
| 132 | * \param[in] in input buffer of unpacked bits |
| 133 | * \param[in] in_ofs offset into input buffer |
| 134 | * \param[in] num_bits number of bits |
| 135 | * \param[in] lsb_mode Encode bits in LSB orde instead of MSB |
| 136 | * \returns length in bytes (max written offset of output buffer + 1) |
| 137 | */ |
Sylvain Munaut | aeb1077 | 2011-01-21 12:22:30 +0100 | [diff] [blame] | 138 | int osmo_ubit2pbit_ext(pbit_t *out, unsigned int out_ofs, |
| 139 | const ubit_t *in, unsigned int in_ofs, |
| 140 | unsigned int num_bits, int lsb_mode) |
| 141 | { |
| 142 | int i, op, bn; |
| 143 | for (i=0; i<num_bits; i++) { |
| 144 | op = out_ofs + i; |
| 145 | bn = lsb_mode ? (op&7) : (7-(op&7)); |
| 146 | if (in[in_ofs+i]) |
| 147 | out[op>>3] |= 1 << bn; |
| 148 | else |
| 149 | out[op>>3] &= ~(1 << bn); |
| 150 | } |
| 151 | return ((out_ofs + num_bits - 1) >> 3) + 1; |
| 152 | } |
| 153 | |
Harald Welte | ba6988b | 2011-08-17 12:46:48 +0200 | [diff] [blame] | 154 | /*! \brief convert packed bits to unpacked bits (extended options) |
| 155 | * \param[out] out output buffer of unpacked bits |
| 156 | * \param[in] out_ofs offset into output buffer |
| 157 | * \param[in] in input buffer of packed bits |
| 158 | * \param[in] in_ofs offset into input buffer |
| 159 | * \param[in] num_bits number of bits |
| 160 | * \param[in] lsb_mode Encode bits in LSB orde instead of MSB |
| 161 | * \returns length in bytes (max written offset of output buffer + 1) |
| 162 | */ |
Sylvain Munaut | aeb1077 | 2011-01-21 12:22:30 +0100 | [diff] [blame] | 163 | int osmo_pbit2ubit_ext(ubit_t *out, unsigned int out_ofs, |
| 164 | const pbit_t *in, unsigned int in_ofs, |
| 165 | unsigned int num_bits, int lsb_mode) |
| 166 | { |
| 167 | int i, ip, bn; |
| 168 | for (i=0; i<num_bits; i++) { |
| 169 | ip = in_ofs + i; |
| 170 | bn = lsb_mode ? (ip&7) : (7-(ip&7)); |
| 171 | out[out_ofs+i] = !!(in[ip>>3] & (1<<bn)); |
| 172 | } |
| 173 | return out_ofs + num_bits; |
| 174 | } |
Harald Welte | ba6988b | 2011-08-17 12:46:48 +0200 | [diff] [blame] | 175 | |
Harald Welte | de6e498 | 2012-12-06 21:25:27 +0100 | [diff] [blame] | 176 | /*! \brief generalized bit reversal function |
| 177 | * \param[in] x the 32bit value to be reversed |
| 178 | * \param[in] k the type of reversal requested |
| 179 | * \returns the reversed 32bit dword |
| 180 | * |
| 181 | * This function reverses the bit order within a 32bit word. Depending |
| 182 | * on "k", it either reverses all bits in a 32bit dword, or the bytes in |
| 183 | * the dword, or the bits in each byte of a dword, or simply swaps the |
| 184 | * two 16bit words in a dword. See Chapter 7 "Hackers Delight" |
| 185 | */ |
Harald Welte | 712691d | 2011-09-01 14:47:31 +0200 | [diff] [blame] | 186 | uint32_t osmo_bit_reversal(uint32_t x, enum osmo_br_mode k) |
| 187 | { |
| 188 | if (k & 1) x = (x & 0x55555555) << 1 | (x & 0xAAAAAAAA) >> 1; |
| 189 | if (k & 2) x = (x & 0x33333333) << 2 | (x & 0xCCCCCCCC) >> 2; |
| 190 | if (k & 4) x = (x & 0x0F0F0F0F) << 4 | (x & 0xF0F0F0F0) >> 4; |
| 191 | if (k & 8) x = (x & 0x00FF00FF) << 8 | (x & 0xFF00FF00) >> 8; |
| 192 | if (k & 16) x = (x & 0x0000FFFF) << 16 | (x & 0xFFFF0000) >> 16; |
| 193 | |
| 194 | return x; |
| 195 | } |
| 196 | |
Harald Welte | de6e498 | 2012-12-06 21:25:27 +0100 | [diff] [blame] | 197 | /*! \brief reverse the bit-order in each byte of a dword |
| 198 | * \param[in] x 32bit input value |
| 199 | * \returns 32bit value where bits of each byte have been reversed |
| 200 | * |
| 201 | * See Chapter 7 "Hackers Delight" |
| 202 | */ |
Harald Welte | 712691d | 2011-09-01 14:47:31 +0200 | [diff] [blame] | 203 | uint32_t osmo_revbytebits_32(uint32_t x) |
| 204 | { |
| 205 | x = (x & 0x55555555) << 1 | (x & 0xAAAAAAAA) >> 1; |
| 206 | x = (x & 0x33333333) << 2 | (x & 0xCCCCCCCC) >> 2; |
| 207 | x = (x & 0x0F0F0F0F) << 4 | (x & 0xF0F0F0F0) >> 4; |
| 208 | |
| 209 | return x; |
| 210 | } |
| 211 | |
Harald Welte | de6e498 | 2012-12-06 21:25:27 +0100 | [diff] [blame] | 212 | /*! \brief reverse the bit order in a byte |
| 213 | * \param[in] x 8bit input value |
| 214 | * \returns 8bit value where bits order has been reversed |
| 215 | * |
| 216 | * See Chapter 7 "Hackers Delight" |
| 217 | */ |
Harald Welte | 712691d | 2011-09-01 14:47:31 +0200 | [diff] [blame] | 218 | uint32_t osmo_revbytebits_8(uint8_t x) |
| 219 | { |
| 220 | x = (x & 0x55) << 1 | (x & 0xAA) >> 1; |
| 221 | x = (x & 0x33) << 2 | (x & 0xCC) >> 2; |
| 222 | x = (x & 0x0F) << 4 | (x & 0xF0) >> 4; |
| 223 | |
| 224 | return x; |
| 225 | } |
| 226 | |
Harald Welte | de6e498 | 2012-12-06 21:25:27 +0100 | [diff] [blame] | 227 | /*! \brief reverse bit-order of each byte in a buffer |
Katerina Barone-Adesi | c28c6a0 | 2013-02-15 13:27:59 +0100 | [diff] [blame] | 228 | * \param[in] buf buffer containing bytes to be bit-reversed |
| 229 | * \param[in] len length of buffer in bytes |
Harald Welte | de6e498 | 2012-12-06 21:25:27 +0100 | [diff] [blame] | 230 | * |
| 231 | * This function reverses the bits in each byte of the buffer |
| 232 | */ |
Harald Welte | 712691d | 2011-09-01 14:47:31 +0200 | [diff] [blame] | 233 | void osmo_revbytebits_buf(uint8_t *buf, int len) |
| 234 | { |
| 235 | unsigned int i; |
| 236 | unsigned int unaligned_cnt; |
| 237 | int len_remain = len; |
| 238 | |
| 239 | unaligned_cnt = ((unsigned long)buf & 3); |
| 240 | for (i = 0; i < unaligned_cnt; i++) { |
| 241 | buf[i] = osmo_revbytebits_8(buf[i]); |
| 242 | len_remain--; |
| 243 | if (len_remain <= 0) |
| 244 | return; |
| 245 | } |
| 246 | |
Sylvain Munaut | 01e0604 | 2013-01-03 09:36:16 +0100 | [diff] [blame] | 247 | for (i = unaligned_cnt; i + 3 < len; i += 4) { |
Max | 08621a8 | 2016-01-21 17:16:56 +0100 | [diff] [blame] | 248 | osmo_store32be(osmo_revbytebits_32(osmo_load32be(buf + i)), buf + i); |
Harald Welte | 712691d | 2011-09-01 14:47:31 +0200 | [diff] [blame] | 249 | len_remain -= 4; |
| 250 | } |
| 251 | |
| 252 | for (i = len - len_remain; i < len; i++) { |
| 253 | buf[i] = osmo_revbytebits_8(buf[i]); |
| 254 | len_remain--; |
| 255 | } |
| 256 | } |
| 257 | |
Sylvain Munaut | dca7d2c | 2012-04-18 21:53:23 +0200 | [diff] [blame] | 258 | /*! @} */ |