| /* |
| * (C) 2011 by Harald Welte <laforge@gnumonks.org> |
| * (C) 2011 by Sylvain Munaut <tnt@246tNt.com> |
| * |
| * All Rights Reserved |
| * |
| * SPDX-License-Identifier: GPL-2.0+ |
| * |
| * 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 <osmocom/core/bits.h> |
| |
| /*! \addtogroup bits |
| * @{ |
| * Osmocom bit level support code. |
| * |
| * This module implements the notion of different bit-fields, such as |
| * - unpacked bits (\ref ubit_t), i.e. 1 bit per byte |
| * - packed bits (\ref pbit_t), i.e. 8 bits per byte |
| * - soft bits (\ref sbit_t), 1 bit per byte from -127 to 127 |
| * |
| * \file bits.c */ |
| |
| /*! 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; |
| } |
| |
| /*! Shift unaligned input to octet-aligned output |
| * \param[out] out output buffer, unaligned |
| * \param[in] in input buffer, octet-aligned |
| * \param[in] num_nibbles number of nibbles |
| */ |
| void osmo_nibble_shift_right(uint8_t *out, const uint8_t *in, |
| unsigned int num_nibbles) |
| { |
| unsigned int i, num_whole_bytes = num_nibbles / 2; |
| if (!num_whole_bytes) |
| return; |
| |
| /* first byte: upper nibble empty, lower nibble from src */ |
| out[0] = (in[0] >> 4); |
| |
| /* bytes 1.. */ |
| for (i = 1; i < num_whole_bytes; i++) |
| out[i] = ((in[i - 1] & 0xF) << 4) | (in[i] >> 4); |
| |
| /* shift the last nibble, in case there's an odd count */ |
| i = num_whole_bytes; |
| if (num_nibbles & 1) |
| out[i] = ((in[i - 1] & 0xF) << 4) | (in[i] >> 4); |
| else |
| out[i] = (in[i - 1] & 0xF) << 4; |
| } |
| |
| /*! Shift unaligned input to octet-aligned output |
| * \param[out] out output buffer, octet-aligned |
| * \param[in] in input buffer, unaligned |
| * \param[in] num_nibbles number of nibbles |
| */ |
| void osmo_nibble_shift_left_unal(uint8_t *out, const uint8_t *in, |
| unsigned int num_nibbles) |
| { |
| unsigned int i, num_whole_bytes = num_nibbles / 2; |
| if (!num_whole_bytes) |
| return; |
| |
| for (i = 0; i < num_whole_bytes; i++) |
| out[i] = ((in[i] & 0xF) << 4) | (in[i + 1] >> 4); |
| |
| /* shift the last nibble, in case there's an odd count */ |
| i = num_whole_bytes; |
| if (num_nibbles & 1) |
| out[i] = (in[i] & 0xF) << 4; |
| } |
| |
| /*! convert unpacked bits to soft bits |
| * \param[out] out output buffer of soft bits |
| * \param[in] in input buffer of unpacked bits |
| * \param[in] num_bits number of bits |
| */ |
| void osmo_ubit2sbit(sbit_t *out, const ubit_t *in, unsigned int num_bits) |
| { |
| unsigned int i; |
| for (i = 0; i < num_bits; i++) |
| out[i] = in[i] ? -127 : 127; |
| } |
| |
| /*! convert soft bits to unpacked bits |
| * \param[out] out output buffer of unpacked bits |
| * \param[in] in input buffer of soft bits |
| * \param[in] num_bits number of bits |
| */ |
| void osmo_sbit2ubit(ubit_t *out, const sbit_t *in, unsigned int num_bits) |
| { |
| unsigned int i; |
| for (i = 0; i < num_bits; i++) |
| out[i] = in[i] < 0; |
| } |
| |
| /*! 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 |
| * \return number of bytes used in \ref out |
| */ |
| 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; |
| } |
| |
| /*! 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; |
| } |
| |
| /*! 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; |
| } |
| |
| /*! 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; |
| } |
| |
| /*! 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; |
| } |
| |
| /*! 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; |
| } |
| |
| /*! reverse bit-order of each byte in a buffer |
| * \param[in] buf buffer containing bytes to be bit-reversed |
| * \param[in] len 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) { |
| osmo_store32be(osmo_revbytebits_32(osmo_load32be(buf + i)), buf + i); |
| len_remain -= 4; |
| } |
| |
| for (i = len - len_remain; i < len; i++) { |
| buf[i] = osmo_revbytebits_8(buf[i]); |
| len_remain--; |
| } |
| } |
| |
| /*! @} */ |