| |
| #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 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 |
| */ |
| 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; |
| } |
| |
| /* generalized bit reversal function, 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; |
| } |
| |
| /* generalized bit reversal function, 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; |
| } |
| |
| 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; |
| } |
| |
| 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 < len; i += 4) { |
| uint32_t *cur = (uint32_t *) (buf + i); |
| *cur = osmo_revbytebits_32(*cur); |
| len_remain -= 4; |
| } |
| |
| for (i = len - len_remain; i < len; i++) { |
| buf[i] = osmo_revbytebits_8(buf[i]); |
| len_remain--; |
| } |
| } |
| |
| /*! }@ */ |