mirror of https://gerrit.osmocom.org/libosmocore
308 lines
8.5 KiB
C
308 lines
8.5 KiB
C
/*
|
|
* (C) 2011 by Harald Welte <laforge@gnumonks.org>
|
|
* (C) 2011 by Sylvain Munaut <tnt@246tNt.com>
|
|
*
|
|
* All Rights Reserved
|
|
*
|
|
* 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
|
|
* @{
|
|
*/
|
|
|
|
/*! \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 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;
|
|
}
|
|
|
|
/*! \brief 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;
|
|
}
|
|
|
|
/*! \brief 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;
|
|
}
|
|
|
|
/*! \brief 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;
|
|
}
|
|
|
|
/*! \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
|
|
* \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;
|
|
}
|
|
|
|
/*! \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[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--;
|
|
}
|
|
}
|
|
|
|
/*! @} */
|