lib and libpayload: Add popcnt functions
Add 32-bit `popcnt` and 64-bit `popcnt64` helpers.
Change-Id: I2e6a1007e475b662a85c067d96f81326e7f02905
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/46421
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
diff --git a/src/include/lib.h b/src/include/lib.h
index a0003d3..5c6eef2 100644
--- a/src/include/lib.h
+++ b/src/include/lib.h
@@ -46,6 +46,8 @@
*/
size_t hexstrtobin(const char *str, uint8_t *buf, size_t len);
+/* Population Count: number of bits that are one */
+static inline int popcnt(u32 x) { return __builtin_popcount(x); }
/* Count Leading Zeroes: clz(0) == 32, clz(0xf) == 28, clz(1 << 31) == 0 */
static inline int clz(u32 x) { return x ? __builtin_clz(x) : sizeof(x) * 8; }
/* Integer binary logarithm (rounding down): log2(0) == -1, log2(5) == 2 */
@@ -56,6 +58,7 @@
/* Integer binary logarithm (rounding up): log2_ceil(0) == -1, log2(5) == 3 */
static inline int log2_ceil(u32 x) { return (x == 0) ? -1 : log2(x * 2 - 1); }
+static inline int popcnt64(u64 x) { return __builtin_popcountll(x); }
static inline int clz64(u64 x) { return x ? __builtin_clzll(x) : sizeof(x) * 8; }
static inline int log2_64(u64 x) { return sizeof(x) * 8 - clz64(x) - 1; }
static inline int __ffs64(u64 x) { return log2_64(x & (u64)(-(s64)x)); }