int: Backport C23's bit utilities

1 files changed, 57 insertions, 0 deletions

diff --git a/tests/int.c b/tests/int.c
index 0039862..e59efde 100644
--- a/tests/int.c
+++ b/tests/int.c
@@ -60,5 +60,62 @@ int main(void) {
 	assert(bswap((uint32_t)0x12345678) == 0x78563412);
 	assert(bswap((uint64_t)0x1234567812345678) == 0x7856341278563412);
 
+	assert(count_ones(0x0) == 0);
+	assert(count_ones(0x1) == 1);
+	assert(count_ones(0x2) == 1);
+	assert(count_ones(0x3) == 2);
+	assert(count_ones(0x137F) == 10);
+
+	assert(count_zeros(0) == INT_WIDTH);
+	assert(count_zeros(0L) == LONG_WIDTH);
+	assert(count_zeros(0LL) == LLONG_WIDTH);
+	assert(count_zeros((uint8_t)0) == 8);
+	assert(count_zeros((uint16_t)0) == 16);
+	assert(count_zeros((uint32_t)0) == 32);
+	assert(count_zeros((uint64_t)0) == 64);
+
+	assert(rotate_left((uint8_t)0xA1, 4) == 0x1A);
+	assert(rotate_left((uint16_t)0x1234, 12) == 0x4123);
+	assert(rotate_left((uint32_t)0x12345678, 20) == 0x67812345);
+	assert(rotate_left((uint32_t)0x12345678, 0) == 0x12345678);
+
+	assert(rotate_right((uint8_t)0xA1, 4) == 0x1A);
+	assert(rotate_right((uint16_t)0x1234, 12) == 0x2341);
+	assert(rotate_right((uint32_t)0x12345678, 20) == 0x45678123);
+	assert(rotate_right((uint32_t)0x12345678, 0) == 0x12345678);
+
+	for (int i = 0; i < 16; ++i) {
+		uint16_t n = (uint16_t)1 << i;
+		for (int j = i; j < 16; ++j) {
+			uint16_t m = (uint16_t)1 << j;
+			uint16_t nm = n | m;
+			assert(count_ones(nm) == 1 + (n != m));
+			assert(count_zeros(nm) == 15 - (n != m));
+			assert(leading_zeros(nm) == 15 - j);
+			assert(trailing_zeros(nm) == i);
+			assert(first_leading_one(nm) == j + 1);
+			assert(first_trailing_one(nm) == i + 1);
+			assert(bit_width(nm) == j + 1);
+			assert(bit_floor(nm) == m);
+			if (n == m) {
+				assert(bit_ceil(nm) == m);
+				assert(has_single_bit(nm));
+			} else {
+				if (j < 15) {
+					assert(bit_ceil(nm) == (m << 1));
+				}
+				assert(!has_single_bit(nm));
+			}
+		}
+	}
+
+	assert(leading_zeros((uint16_t)0) == 16);
+	assert(trailing_zeros((uint16_t)0) == 16);
+	assert(first_leading_one(0) == 0);
+	assert(first_trailing_one(0) == 0);
+	assert(bit_width(0) == 0);
+	assert(bit_floor(0) == 0);
+	assert(bit_ceil(0) == 1);
+
 	return EXIT_SUCCESS;
 }