Function partition_mismatch2

Source/astcenc_find_best_partitioning.cpp:253–263

* @brief Compute bit-mismatch for partitioning in 2-partition mode. * * @param a The texel assignment bitvector for the block. * @param b The texel assignment bitvector for the partition table. * * @return The number of bit mismatches. */

 * @return    The number of bit mismatches.
 */
static inline uint8_t partition_mismatch2(
	const uint64_t a[2],
	const uint64_t b[2]
) {
	int v1 = popcount(a[0] ^ b[0]) + popcount(a[1] ^ b[1]);
	int v2 = popcount(a[0] ^ b[1]) + popcount(a[1] ^ b[0]);

	// Divide by 2 because XOR always counts errors twice, once when missing
	// in the expected position, and again when present in the wrong partition
	return static_cast<uint8_t>(astc::min(v1, v2) / 2);
}

/**
 * @brief Compute bit-mismatch for partitioning in 3-partition mode.