2011-01-19 09:10:16 +00:00
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#include <stdint.h>
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2011-03-22 15:36:13 +00:00
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#include <osmocom/core/bits.h>
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2011-01-19 09:10:16 +00:00
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2011-08-17 10:46:48 +00:00
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/*! \addtogroup bits
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* @{
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*/
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/*! \file bits.c
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* \brief Osmocom bit level support code
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*/
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/*! \brief convert unpacked bits to packed bits, return length in bytes
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* \param[out] out output buffer of packed bits
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* \param[in] in input buffer of unpacked bits
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* \param[in] num_bits number of bits
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*/
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2011-01-19 09:10:16 +00:00
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int osmo_ubit2pbit(pbit_t *out, const ubit_t *in, unsigned int num_bits)
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{
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unsigned int i;
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uint8_t curbyte = 0;
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pbit_t *outptr = out;
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for (i = 0; i < num_bits; i++) {
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uint8_t bitnum = 7 - (i % 8);
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curbyte |= (in[i] << bitnum);
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2011-01-22 21:48:37 +00:00
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if(i % 8 == 7){
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2011-01-19 09:10:16 +00:00
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*outptr++ = curbyte;
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curbyte = 0;
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}
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}
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/* we have a non-modulo-8 bitcount */
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if (i % 8)
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*outptr++ = curbyte;
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return outptr - out;
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}
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2011-08-17 10:46:48 +00:00
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/*! \brief convert packed bits to unpacked bits, return length in bytes
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* \param[out] out output buffer of unpacked bits
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* \param[in] in input buffer of packed bits
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* \param[in] num_bits number of bits
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*/
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2011-01-19 09:10:16 +00:00
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int osmo_pbit2ubit(ubit_t *out, const pbit_t *in, unsigned int num_bits)
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{
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unsigned int i;
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ubit_t *cur = out;
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ubit_t *limit = out + num_bits;
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for (i = 0; i < (num_bits/8)+1; i++) {
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pbit_t byte = in[i];
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*cur++ = (byte >> 7) & 1;
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if (cur >= limit)
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break;
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*cur++ = (byte >> 6) & 1;
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if (cur >= limit)
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break;
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*cur++ = (byte >> 5) & 1;
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if (cur >= limit)
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break;
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*cur++ = (byte >> 4) & 1;
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if (cur >= limit)
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break;
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*cur++ = (byte >> 3) & 1;
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if (cur >= limit)
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break;
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*cur++ = (byte >> 2) & 1;
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if (cur >= limit)
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break;
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*cur++ = (byte >> 1) & 1;
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if (cur >= limit)
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break;
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*cur++ = (byte >> 0) & 1;
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if (cur >= limit)
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break;
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}
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return cur - out;
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}
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2011-01-21 11:22:30 +00:00
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2011-08-17 10:46:48 +00:00
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/*! \brief convert unpacked bits to packed bits (extended options)
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* \param[out] out output buffer of packed bits
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* \param[in] out_ofs offset into output buffer
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* \param[in] in input buffer of unpacked bits
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* \param[in] in_ofs offset into input buffer
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* \param[in] num_bits number of bits
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* \param[in] lsb_mode Encode bits in LSB orde instead of MSB
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* \returns length in bytes (max written offset of output buffer + 1)
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*/
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2011-01-21 11:22:30 +00:00
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int osmo_ubit2pbit_ext(pbit_t *out, unsigned int out_ofs,
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const ubit_t *in, unsigned int in_ofs,
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unsigned int num_bits, int lsb_mode)
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{
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int i, op, bn;
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for (i=0; i<num_bits; i++) {
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op = out_ofs + i;
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bn = lsb_mode ? (op&7) : (7-(op&7));
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if (in[in_ofs+i])
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out[op>>3] |= 1 << bn;
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else
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out[op>>3] &= ~(1 << bn);
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}
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return ((out_ofs + num_bits - 1) >> 3) + 1;
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}
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2011-08-17 10:46:48 +00:00
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/*! \brief convert packed bits to unpacked bits (extended options)
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* \param[out] out output buffer of unpacked bits
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* \param[in] out_ofs offset into output buffer
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* \param[in] in input buffer of packed bits
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* \param[in] in_ofs offset into input buffer
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* \param[in] num_bits number of bits
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* \param[in] lsb_mode Encode bits in LSB orde instead of MSB
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* \returns length in bytes (max written offset of output buffer + 1)
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*/
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2011-01-21 11:22:30 +00:00
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int osmo_pbit2ubit_ext(ubit_t *out, unsigned int out_ofs,
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const pbit_t *in, unsigned int in_ofs,
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unsigned int num_bits, int lsb_mode)
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{
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int i, ip, bn;
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for (i=0; i<num_bits; i++) {
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ip = in_ofs + i;
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bn = lsb_mode ? (ip&7) : (7-(ip&7));
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out[out_ofs+i] = !!(in[ip>>3] & (1<<bn));
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}
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return out_ofs + num_bits;
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}
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2011-08-17 10:46:48 +00:00
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2012-12-06 20:25:27 +00:00
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/*! \brief generalized bit reversal function
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* \param[in] x the 32bit value to be reversed
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* \param[in] k the type of reversal requested
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* \returns the reversed 32bit dword
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*
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* This function reverses the bit order within a 32bit word. Depending
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* on "k", it either reverses all bits in a 32bit dword, or the bytes in
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* the dword, or the bits in each byte of a dword, or simply swaps the
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* two 16bit words in a dword. See Chapter 7 "Hackers Delight"
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*/
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2011-09-01 12:47:31 +00:00
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uint32_t osmo_bit_reversal(uint32_t x, enum osmo_br_mode k)
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{
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if (k & 1) x = (x & 0x55555555) << 1 | (x & 0xAAAAAAAA) >> 1;
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if (k & 2) x = (x & 0x33333333) << 2 | (x & 0xCCCCCCCC) >> 2;
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if (k & 4) x = (x & 0x0F0F0F0F) << 4 | (x & 0xF0F0F0F0) >> 4;
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if (k & 8) x = (x & 0x00FF00FF) << 8 | (x & 0xFF00FF00) >> 8;
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if (k & 16) x = (x & 0x0000FFFF) << 16 | (x & 0xFFFF0000) >> 16;
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return x;
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}
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2012-12-06 20:25:27 +00:00
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/*! \brief reverse the bit-order in each byte of a dword
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* \param[in] x 32bit input value
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* \returns 32bit value where bits of each byte have been reversed
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*
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* See Chapter 7 "Hackers Delight"
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*/
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2011-09-01 12:47:31 +00:00
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uint32_t osmo_revbytebits_32(uint32_t x)
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{
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x = (x & 0x55555555) << 1 | (x & 0xAAAAAAAA) >> 1;
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x = (x & 0x33333333) << 2 | (x & 0xCCCCCCCC) >> 2;
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x = (x & 0x0F0F0F0F) << 4 | (x & 0xF0F0F0F0) >> 4;
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return x;
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}
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2012-12-06 20:25:27 +00:00
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/*! \brief reverse the bit order in a byte
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* \param[in] x 8bit input value
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* \returns 8bit value where bits order has been reversed
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*
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* See Chapter 7 "Hackers Delight"
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*/
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2011-09-01 12:47:31 +00:00
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uint32_t osmo_revbytebits_8(uint8_t x)
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{
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x = (x & 0x55) << 1 | (x & 0xAA) >> 1;
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x = (x & 0x33) << 2 | (x & 0xCC) >> 2;
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x = (x & 0x0F) << 4 | (x & 0xF0) >> 4;
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return x;
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}
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2012-12-06 20:25:27 +00:00
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/*! \brief reverse bit-order of each byte in a buffer
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2013-02-15 12:27:59 +00:00
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* \param[in] buf buffer containing bytes to be bit-reversed
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* \param[in] len length of buffer in bytes
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2012-12-06 20:25:27 +00:00
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*
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* This function reverses the bits in each byte of the buffer
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*/
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2011-09-01 12:47:31 +00:00
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void osmo_revbytebits_buf(uint8_t *buf, int len)
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{
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unsigned int i;
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unsigned int unaligned_cnt;
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int len_remain = len;
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unaligned_cnt = ((unsigned long)buf & 3);
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for (i = 0; i < unaligned_cnt; i++) {
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buf[i] = osmo_revbytebits_8(buf[i]);
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len_remain--;
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if (len_remain <= 0)
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return;
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}
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2013-01-03 08:36:16 +00:00
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for (i = unaligned_cnt; i + 3 < len; i += 4) {
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2011-09-01 12:47:31 +00:00
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uint32_t *cur = (uint32_t *) (buf + i);
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*cur = osmo_revbytebits_32(*cur);
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len_remain -= 4;
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}
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for (i = len - len_remain; i < len; i++) {
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buf[i] = osmo_revbytebits_8(buf[i]);
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len_remain--;
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}
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}
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2012-04-18 19:53:23 +00:00
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/*! @} */
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