libosmocore  0.9.0
Osmocom core library
soft, unpacked and packed bits

Files

file  bits.h
 Osmocom bit level support code.
 
file  bits.c
 Osmocom bit level support code.
 

Typedefs

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)
 

Enumerations

enum  osmo_br_mode { OSMO_BR_BITS_IN_DWORD = 31, OSMO_BR_BYTES_IN_DWORD = 24, OSMO_BR_BITS_IN_BYTE = 7, OSMO_BR_WORD_SWAP = 16 }
 bit-reversal mode for osmo_bit_reversal() More...
 

Functions

static unsigned int osmo_pbit_bytesize (unsigned int num_bits)
 determine how many bytes we would need for num_bits packed bits More...
 
int osmo_ubit2pbit (pbit_t *out, const ubit_t *in, unsigned int num_bits)
 convert unpacked bits to packed bits, return length in bytes More...
 
int osmo_pbit2ubit (ubit_t *out, const pbit_t *in, unsigned int num_bits)
 convert packed bits to unpacked bits, return length in bytes More...
 
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)
 convert unpacked bits to packed bits (extended options) More...
 
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)
 convert packed bits to unpacked bits (extended options) More...
 
uint32_t osmo_bit_reversal (uint32_t x, enum osmo_br_mode k)
 generic bit reversal function More...
 
uint32_t osmo_revbytebits_32 (uint32_t x)
 reverse the bit-order in each byte of a dword More...
 
uint32_t osmo_revbytebits_8 (uint8_t x)
 reverse the bit order in a byte More...
 
void osmo_revbytebits_buf (uint8_t *buf, int len)
 reverse bit-order of each byte in a buffer More...
 
static uint16_t osmo_rol16 (uint16_t in, unsigned shift)
 left circular shift More...
 

Detailed Description

Enumeration Type Documentation

bit-reversal mode for osmo_bit_reversal()

Enumerator
OSMO_BR_BITS_IN_DWORD 

reverse all bits in a 32bit dword

OSMO_BR_BYTES_IN_DWORD 

reverse byte order in a 32bit dword

OSMO_BR_BITS_IN_BYTE 

reverse bits of each byte in a 32bit dword

OSMO_BR_WORD_SWAP 

swap the two 16bit words in a 32bit dword

Function Documentation

uint32_t osmo_bit_reversal ( uint32_t  x,
enum osmo_br_mode  k 
)

generic bit reversal function

generalized bit reversal function

Parameters
[in]xthe 32bit value to be reversed
[in]kthe 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"

int osmo_pbit2ubit ( ubit_t out,
const pbit_t in,
unsigned int  num_bits 
)

convert packed bits to unpacked bits, return length in bytes

Parameters
[out]outoutput buffer of unpacked bits
[in]ininput buffer of packed bits
[in]num_bitsnumber of bits

Referenced by osmo_pbit_bytesize().

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 
)

convert packed bits to unpacked bits (extended options)

Parameters
[out]outoutput buffer of unpacked bits
[in]out_ofsoffset into output buffer
[in]ininput buffer of packed bits
[in]in_ofsoffset into input buffer
[in]num_bitsnumber of bits
[in]lsb_modeEncode bits in LSB orde instead of MSB
Returns
length in bytes (max written offset of output buffer + 1)

Referenced by osmo_pbit_bytesize().

static unsigned int osmo_pbit_bytesize ( unsigned int  num_bits)
inlinestatic

determine how many bytes we would need for num_bits packed bits

Parameters
[in]num_bitsNumber of packed bits

References osmo_pbit2ubit(), osmo_pbit2ubit_ext(), osmo_ubit2pbit(), and osmo_ubit2pbit_ext().

uint32_t osmo_revbytebits_32 ( uint32_t  x)

reverse the bit-order in each byte of a dword

Parameters
[in]x32bit input value
Returns
32bit value where bits of each byte have been reversed

See Chapter 7 "Hackers Delight"

Referenced by osmo_revbytebits_buf().

uint32_t osmo_revbytebits_8 ( uint8_t  x)

reverse the bit order in a byte

Parameters
[in]x8bit input value
Returns
8bit value where bits order has been reversed

See Chapter 7 "Hackers Delight"

Referenced by osmo_revbytebits_buf().

void osmo_revbytebits_buf ( uint8_t *  buf,
int  len 
)

reverse bit-order of each byte in a buffer

Parameters
[in]bufbuffer containing bytes to be bit-reversed
[in]lenlength of buffer in bytes

This function reverses the bits in each byte of the buffer

References osmo_revbytebits_32(), and osmo_revbytebits_8().

static uint16_t osmo_rol16 ( uint16_t  in,
unsigned  shift 
)
inlinestatic

left circular shift

Parameters
[in]inThe 16 bit unsigned integer to be rotated
[in]shiftNumber of bits to shift in to, [0;16] bits
Returns
shifted value
int osmo_ubit2pbit ( pbit_t out,
const ubit_t in,
unsigned int  num_bits 
)

convert unpacked bits to packed bits, return length in bytes

Parameters
[out]outoutput buffer of packed bits
[in]ininput buffer of unpacked bits
[in]num_bitsnumber of bits

Referenced by osmo_pbit_bytesize().

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 
)

convert unpacked bits to packed bits (extended options)

Parameters
[out]outoutput buffer of packed bits
[in]out_ofsoffset into output buffer
[in]ininput buffer of unpacked bits
[in]in_ofsoffset into input buffer
[in]num_bitsnumber of bits
[in]lsb_modeEncode bits in LSB orde instead of MSB
Returns
length in bytes (max written offset of output buffer + 1)

Referenced by osmo_pbit_bytesize().