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 | |
Harald Welte | ba6988b | 2011-08-17 12:46:48 +0200 | [diff] [blame] | 64 | /*! \brief convert packed bits to unpacked bits, return length in bytes |
| 65 | * \param[out] out output buffer of unpacked bits |
| 66 | * \param[in] in input buffer of packed bits |
| 67 | * \param[in] num_bits number of bits |
| 68 | */ |
Harald Welte | 2230c13 | 2011-01-19 10:10:16 +0100 | [diff] [blame] | 69 | int osmo_pbit2ubit(ubit_t *out, const pbit_t *in, unsigned int num_bits) |
| 70 | { |
| 71 | unsigned int i; |
| 72 | ubit_t *cur = out; |
| 73 | ubit_t *limit = out + num_bits; |
| 74 | |
| 75 | for (i = 0; i < (num_bits/8)+1; i++) { |
| 76 | pbit_t byte = in[i]; |
| 77 | *cur++ = (byte >> 7) & 1; |
| 78 | if (cur >= limit) |
| 79 | break; |
| 80 | *cur++ = (byte >> 6) & 1; |
| 81 | if (cur >= limit) |
| 82 | break; |
| 83 | *cur++ = (byte >> 5) & 1; |
| 84 | if (cur >= limit) |
| 85 | break; |
| 86 | *cur++ = (byte >> 4) & 1; |
| 87 | if (cur >= limit) |
| 88 | break; |
| 89 | *cur++ = (byte >> 3) & 1; |
| 90 | if (cur >= limit) |
| 91 | break; |
| 92 | *cur++ = (byte >> 2) & 1; |
| 93 | if (cur >= limit) |
| 94 | break; |
| 95 | *cur++ = (byte >> 1) & 1; |
| 96 | if (cur >= limit) |
| 97 | break; |
| 98 | *cur++ = (byte >> 0) & 1; |
| 99 | if (cur >= limit) |
| 100 | break; |
| 101 | } |
| 102 | return cur - out; |
| 103 | } |
Sylvain Munaut | aeb1077 | 2011-01-21 12:22:30 +0100 | [diff] [blame] | 104 | |
Harald Welte | ba6988b | 2011-08-17 12:46:48 +0200 | [diff] [blame] | 105 | /*! \brief convert unpacked bits to packed bits (extended options) |
| 106 | * \param[out] out output buffer of packed bits |
| 107 | * \param[in] out_ofs offset into output buffer |
| 108 | * \param[in] in input buffer of unpacked bits |
| 109 | * \param[in] in_ofs offset into input buffer |
| 110 | * \param[in] num_bits number of bits |
| 111 | * \param[in] lsb_mode Encode bits in LSB orde instead of MSB |
| 112 | * \returns length in bytes (max written offset of output buffer + 1) |
| 113 | */ |
Sylvain Munaut | aeb1077 | 2011-01-21 12:22:30 +0100 | [diff] [blame] | 114 | int osmo_ubit2pbit_ext(pbit_t *out, unsigned int out_ofs, |
| 115 | const ubit_t *in, unsigned int in_ofs, |
| 116 | unsigned int num_bits, int lsb_mode) |
| 117 | { |
| 118 | int i, op, bn; |
| 119 | for (i=0; i<num_bits; i++) { |
| 120 | op = out_ofs + i; |
| 121 | bn = lsb_mode ? (op&7) : (7-(op&7)); |
| 122 | if (in[in_ofs+i]) |
| 123 | out[op>>3] |= 1 << bn; |
| 124 | else |
| 125 | out[op>>3] &= ~(1 << bn); |
| 126 | } |
| 127 | return ((out_ofs + num_bits - 1) >> 3) + 1; |
| 128 | } |
| 129 | |
Harald Welte | ba6988b | 2011-08-17 12:46:48 +0200 | [diff] [blame] | 130 | /*! \brief convert packed bits to unpacked bits (extended options) |
| 131 | * \param[out] out output buffer of unpacked bits |
| 132 | * \param[in] out_ofs offset into output buffer |
| 133 | * \param[in] in input buffer of packed bits |
| 134 | * \param[in] in_ofs offset into input buffer |
| 135 | * \param[in] num_bits number of bits |
| 136 | * \param[in] lsb_mode Encode bits in LSB orde instead of MSB |
| 137 | * \returns length in bytes (max written offset of output buffer + 1) |
| 138 | */ |
Sylvain Munaut | aeb1077 | 2011-01-21 12:22:30 +0100 | [diff] [blame] | 139 | int osmo_pbit2ubit_ext(ubit_t *out, unsigned int out_ofs, |
| 140 | const pbit_t *in, unsigned int in_ofs, |
| 141 | unsigned int num_bits, int lsb_mode) |
| 142 | { |
| 143 | int i, ip, bn; |
| 144 | for (i=0; i<num_bits; i++) { |
| 145 | ip = in_ofs + i; |
| 146 | bn = lsb_mode ? (ip&7) : (7-(ip&7)); |
| 147 | out[out_ofs+i] = !!(in[ip>>3] & (1<<bn)); |
| 148 | } |
| 149 | return out_ofs + num_bits; |
| 150 | } |
Harald Welte | ba6988b | 2011-08-17 12:46:48 +0200 | [diff] [blame] | 151 | |
Harald Welte | de6e498 | 2012-12-06 21:25:27 +0100 | [diff] [blame] | 152 | /*! \brief generalized bit reversal function |
| 153 | * \param[in] x the 32bit value to be reversed |
| 154 | * \param[in] k the type of reversal requested |
| 155 | * \returns the reversed 32bit dword |
| 156 | * |
| 157 | * This function reverses the bit order within a 32bit word. Depending |
| 158 | * on "k", it either reverses all bits in a 32bit dword, or the bytes in |
| 159 | * the dword, or the bits in each byte of a dword, or simply swaps the |
| 160 | * two 16bit words in a dword. See Chapter 7 "Hackers Delight" |
| 161 | */ |
Harald Welte | 712691d | 2011-09-01 14:47:31 +0200 | [diff] [blame] | 162 | uint32_t osmo_bit_reversal(uint32_t x, enum osmo_br_mode k) |
| 163 | { |
| 164 | if (k & 1) x = (x & 0x55555555) << 1 | (x & 0xAAAAAAAA) >> 1; |
| 165 | if (k & 2) x = (x & 0x33333333) << 2 | (x & 0xCCCCCCCC) >> 2; |
| 166 | if (k & 4) x = (x & 0x0F0F0F0F) << 4 | (x & 0xF0F0F0F0) >> 4; |
| 167 | if (k & 8) x = (x & 0x00FF00FF) << 8 | (x & 0xFF00FF00) >> 8; |
| 168 | if (k & 16) x = (x & 0x0000FFFF) << 16 | (x & 0xFFFF0000) >> 16; |
| 169 | |
| 170 | return x; |
| 171 | } |
| 172 | |
Harald Welte | de6e498 | 2012-12-06 21:25:27 +0100 | [diff] [blame] | 173 | /*! \brief reverse the bit-order in each byte of a dword |
| 174 | * \param[in] x 32bit input value |
| 175 | * \returns 32bit value where bits of each byte have been reversed |
| 176 | * |
| 177 | * See Chapter 7 "Hackers Delight" |
| 178 | */ |
Harald Welte | 712691d | 2011-09-01 14:47:31 +0200 | [diff] [blame] | 179 | uint32_t osmo_revbytebits_32(uint32_t x) |
| 180 | { |
| 181 | x = (x & 0x55555555) << 1 | (x & 0xAAAAAAAA) >> 1; |
| 182 | x = (x & 0x33333333) << 2 | (x & 0xCCCCCCCC) >> 2; |
| 183 | x = (x & 0x0F0F0F0F) << 4 | (x & 0xF0F0F0F0) >> 4; |
| 184 | |
| 185 | return x; |
| 186 | } |
| 187 | |
Harald Welte | de6e498 | 2012-12-06 21:25:27 +0100 | [diff] [blame] | 188 | /*! \brief reverse the bit order in a byte |
| 189 | * \param[in] x 8bit input value |
| 190 | * \returns 8bit value where bits order has been reversed |
| 191 | * |
| 192 | * See Chapter 7 "Hackers Delight" |
| 193 | */ |
Harald Welte | 712691d | 2011-09-01 14:47:31 +0200 | [diff] [blame] | 194 | uint32_t osmo_revbytebits_8(uint8_t x) |
| 195 | { |
| 196 | x = (x & 0x55) << 1 | (x & 0xAA) >> 1; |
| 197 | x = (x & 0x33) << 2 | (x & 0xCC) >> 2; |
| 198 | x = (x & 0x0F) << 4 | (x & 0xF0) >> 4; |
| 199 | |
| 200 | return x; |
| 201 | } |
| 202 | |
Harald Welte | de6e498 | 2012-12-06 21:25:27 +0100 | [diff] [blame] | 203 | /*! \brief reverse bit-order of each byte in a buffer |
Katerina Barone-Adesi | c28c6a0 | 2013-02-15 13:27:59 +0100 | [diff] [blame] | 204 | * \param[in] buf buffer containing bytes to be bit-reversed |
| 205 | * \param[in] len length of buffer in bytes |
Harald Welte | de6e498 | 2012-12-06 21:25:27 +0100 | [diff] [blame] | 206 | * |
| 207 | * This function reverses the bits in each byte of the buffer |
| 208 | */ |
Harald Welte | 712691d | 2011-09-01 14:47:31 +0200 | [diff] [blame] | 209 | void osmo_revbytebits_buf(uint8_t *buf, int len) |
| 210 | { |
| 211 | unsigned int i; |
| 212 | unsigned int unaligned_cnt; |
| 213 | int len_remain = len; |
| 214 | |
| 215 | unaligned_cnt = ((unsigned long)buf & 3); |
| 216 | for (i = 0; i < unaligned_cnt; i++) { |
| 217 | buf[i] = osmo_revbytebits_8(buf[i]); |
| 218 | len_remain--; |
| 219 | if (len_remain <= 0) |
| 220 | return; |
| 221 | } |
| 222 | |
Sylvain Munaut | 01e0604 | 2013-01-03 09:36:16 +0100 | [diff] [blame] | 223 | for (i = unaligned_cnt; i + 3 < len; i += 4) { |
Harald Welte | 712691d | 2011-09-01 14:47:31 +0200 | [diff] [blame] | 224 | uint32_t *cur = (uint32_t *) (buf + i); |
| 225 | *cur = osmo_revbytebits_32(*cur); |
| 226 | len_remain -= 4; |
| 227 | } |
| 228 | |
| 229 | for (i = len - len_remain; i < len; i++) { |
| 230 | buf[i] = osmo_revbytebits_8(buf[i]); |
| 231 | len_remain--; |
| 232 | } |
| 233 | } |
| 234 | |
Sylvain Munaut | dca7d2c | 2012-04-18 21:53:23 +0200 | [diff] [blame] | 235 | /*! @} */ |