diff options
| -rw-r--r-- | include/osmocom/core/bits.h | 22 | ||||
| -rw-r--r-- | src/bits.c | 5 |
2 files changed, 17 insertions, 10 deletions
diff --git a/include/osmocom/core/bits.h b/include/osmocom/core/bits.h index c6a142f8..b1b80406 100644 --- a/include/osmocom/core/bits.h +++ b/include/osmocom/core/bits.h @@ -1,9 +1,6 @@ /*! \file bits.h * Osmocom bit level support code. * - * NOTE on the endianess of pbit_t: - * Bits in a pbit_t are ordered MSB first, i.e. 0x80 is the first bit. - * Bit i in a pbit_t array is array[i/8] & (1<<(7-i%8)) */ #pragma once @@ -19,9 +16,18 @@ * @{ * \file bits.h */ -typedef int8_t sbit_t; /*!< soft bit (-127...127) */ -typedef uint8_t ubit_t; /*!< unpacked bit (0 or 1) */ -typedef uint8_t pbit_t; /*!< packed bis (8 bits in a byte) */ +/*! soft bit with value (-127...127), as commonly used in + * communications receivers such as [viterbi] decoders */ +typedef int8_t sbit_t; + +/*! unpacked bit (0 or 1): 1 bit per byte */ +typedef uint8_t ubit_t; + +/*! packed bits (8 bits in a byte). + * NOTE on the endian-ness of \ref pbit_t: + * - Bits in a \ref pbit_t are ordered MSB first, i.e. 0x80 is the first bit. + * - Bit i in a \ref pbit_t array is array[i/8] & (1<<(7-i%8)) */ +typedef uint8_t pbit_t; /*! determine how many bytes we would need for \a num_bits packed bits * \param[in] num_bits Number of packed bits @@ -95,16 +101,12 @@ enum osmo_br_mode { OSMO_BR_WORD_SWAP = 16, }; -/*! generic bit reversal function */ uint32_t osmo_bit_reversal(uint32_t x, enum osmo_br_mode k); -/* reverse the bits within each byte of a 32bit word */ uint32_t osmo_revbytebits_32(uint32_t x); -/* reverse the bits within a byte */ uint32_t osmo_revbytebits_8(uint8_t x); -/* reverse the bits of each byte in a given buffer */ void osmo_revbytebits_buf(uint8_t *buf, int len); /*! left circular shift @@ -28,6 +28,11 @@ * @{ * 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 |