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lib and libpayload: Add popcnt functions

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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>
This commit is contained in:
Angel Pons
2020-10-14 17:48:05 +02:00
parent e1db55b43e
commit e0ce60c744
2 changed files with 6 additions and 0 deletions
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3
payloads/libpayload/include/libpayload.h
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@ -445,6 +445,8 @@ u8 hex2bin(u8 h);
void hexdump(const void *memory, size_t length);
void fatal(const char *msg) __attribute__((noreturn));
/* 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)
{
@ -455,6 +457,7 @@ static inline int log2(u32 x) { return (int)sizeof(x) * 8 - clz(x) - 1; }
/* Find First Set: __ffs(0xf) == 0, __ffs(0) == -1, __ffs(1 << 31) == 31 */
static inline int __ffs(u32 x) { return log2(x & (u32)(-(s32)x)); }
static inline int popcnt64(u64 x) { return __builtin_popcountll(x); }
static inline int clz64(u64 x)
{
return x ? __builtin_clzll(x) : sizeof(x) * 8;