Function read_bits

Source/astcenc_symbolic_physical.cpp:54–66

* @brief Read up to 8 bits at an arbitrary bit offset. * * The stored value is at most 8 bits, but can be stored at an offset of between 0 and 7 bits so may * span two separate bytes in memory. * * @param bitcount The number of bits to read. * @param bitoffset The bit offset to read from, between 0 and 7. * @param[in,out] ptr The data pointer to read from. * *

 * @return The read value.
 */
static inline int read_bits(
	int bitcount,
	int bitoffset,
	const uint8_t* ptr
) {
	int mask = (1 << bitcount) - 1;
	ptr += bitoffset >> 3;
	bitoffset &= 7;
	int value = ptr[0] | (ptr[1] << 8);
	value >>= bitoffset;
	value &= mask;
	return value;
}

#if !defined(ASTCENC_DECOMPRESS_ONLY)