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#include <bitfield/bitfield.h>
#include <limits.h>
#include <string.h>
#include <stddef.h>
#include <sys/param.h>
uint64_t bitmask(const unsigned int bit_count) {
return (((uint64_t)0x1) << bit_count) - 1;
}
unsigned int get_nibble(const uint8_t source[], const unsigned int source_length,
const unsigned int nibble_index) {
unsigned int byte_index = nibble_index / 2;
unsigned int result = get_byte(source, source_length, byte_index);
if(nibble_index % 2 == 0) {
result >>= NIBBLE_SIZE;
}
result &= bitmask(NIBBLE_SIZE);
return result;
}
unsigned int get_byte(const uint8_t source[], const unsigned int source_length,
const unsigned int byte_index) {
if(byte_index < source_length) {
return source[byte_index];
}
return 0;
}
uint64_t get_bitfield(const uint8_t source[], const unsigned int source_length,
const unsigned int offset, const unsigned int 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 unsigned int nibble_index, const unsigned int value,
uint8_t* destination, const unsigned int 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 unsigned int offset,
const unsigned int bit_count, uint8_t destination[],
unsigned int 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);
}
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