| /* |
| * (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. |
| * |
| */ |
| |
| #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 order 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) |
| { |
| unsigned 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 order 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) |
| { |
| unsigned 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; |
| } |
| |
| /* look-up table for bit-reversal within a byte. Generated using: |
| int i,k; |
| for (i = 0 ; i < 256 ; i++) { |
| uint8_t sample = 0 ; |
| for (k = 0; k<8; k++) { |
| if ( i & 1 << k ) sample |= 0x80 >> k; |
| } |
| flip_table[i] = sample; |
| } |
| */ |
| static const uint8_t flip_table[256] = { |
| 0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0, 0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70, 0xf0, |
| 0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8, 0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8, 0x78, 0xf8, |
| 0x04, 0x84, 0x44, 0xc4, 0x24, 0xa4, 0x64, 0xe4, 0x14, 0x94, 0x54, 0xd4, 0x34, 0xb4, 0x74, 0xf4, |
| 0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec, 0x1c, 0x9c, 0x5c, 0xdc, 0x3c, 0xbc, 0x7c, 0xfc, |
| 0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2, 0x12, 0x92, 0x52, 0xd2, 0x32, 0xb2, 0x72, 0xf2, |
| 0x0a, 0x8a, 0x4a, 0xca, 0x2a, 0xaa, 0x6a, 0xea, 0x1a, 0x9a, 0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa, |
| 0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6, 0x16, 0x96, 0x56, 0xd6, 0x36, 0xb6, 0x76, 0xf6, |
| 0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee, 0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe, |
| 0x01, 0x81, 0x41, 0xc1, 0x21, 0xa1, 0x61, 0xe1, 0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1, |
| 0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9, 0x69, 0xe9, 0x19, 0x99, 0x59, 0xd9, 0x39, 0xb9, 0x79, 0xf9, |
| 0x05, 0x85, 0x45, 0xc5, 0x25, 0xa5, 0x65, 0xe5, 0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5, |
| 0x0d, 0x8d, 0x4d, 0xcd, 0x2d, 0xad, 0x6d, 0xed, 0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd, |
| 0x03, 0x83, 0x43, 0xc3, 0x23, 0xa3, 0x63, 0xe3, 0x13, 0x93, 0x53, 0xd3, 0x33, 0xb3, 0x73, 0xf3, |
| 0x0b, 0x8b, 0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb, 0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb, |
| 0x07, 0x87, 0x47, 0xc7, 0x27, 0xa7, 0x67, 0xe7, 0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7, |
| 0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef, 0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f, 0xff, |
| }; |
| |
| /*! 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 |
| */ |
| uint32_t osmo_revbytebits_8(uint8_t x) |
| { |
| return flip_table[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) |
| { |
| int i; |
| |
| for (i = 0; i < len; i++) |
| buf[i] = flip_table[buf[i]]; |
| } |
| |
| /*! @} */ |