#include <bitfield/bitfield.h> #include <limits.h> #include <string.h> #include <stddef.h> #include <sys/param.h> uint64_t bitmask(const uint8_t bit_count) { return (((uint64_t)0x1) << bit_count) - 1; } uint8_t get_nibble(const uint8_t source[], const uint8_t source_length, const uint8_t nibble_index) { uint8_t byte_index = nibble_index / 2; uint8_t result = get_byte(source, source_length, byte_index); if(nibble_index % 2 == 0) { result >>= NIBBLE_SIZE; } result &= bitmask(NIBBLE_SIZE); return result; } uint8_t get_byte(const uint8_t source[], const uint8_t source_length, const uint8_t byte_index) { if(byte_index < source_length) { return source[byte_index]; } return 0; } uint64_t get_bitfield(const uint8_t source[], const uint8_t source_length, const uint16_t offset, const uint16_t bit_count) { if(bit_count > 64 || bit_count < 1) { // TODO error reporting? return 0; } ArrayOrBytes combined; memset(combined.bytes, 0, sizeof(combined.bytes)); if(copy_bits_right_aligned(source, source_length, offset, bit_count, combined.bytes, sizeof(combined.bytes))) { if(BYTE_ORDER == LITTLE_ENDIAN) { combined.whole = __builtin_bswap64(combined.whole); } } else { // debug("couldn't copy enough bits from source") } return combined.whole; } bool set_nibble(const uint16_t nibble_index, const uint8_t value, uint8_t* destination, const uint16_t destination_length) { return copy_bits(&value, CHAR_BIT, NIBBLE_SIZE, NIBBLE_SIZE, destination, destination_length, nibble_index * NIBBLE_SIZE); } bool set_bitfield(const uint64_t value, const uint16_t offset, const uint16_t bit_count, uint8_t destination[], uint16_t destination_length) { if(value > bitmask(bit_count)) { return false; } ArrayOrBytes combined = { whole: value }; if(BYTE_ORDER == LITTLE_ENDIAN) { combined.whole = __builtin_bswap64(combined.whole); } return copy_bits(combined.bytes, sizeof(combined.bytes), sizeof(combined.bytes) * CHAR_BIT - bit_count, bit_count, destination, destination_length, offset); }