Other-Bit Manipulation-XMM#

_mm_tzcnt_32#

int _mm_tzcnt_32(unsigned int a);

Intel Description

Count the number of trailing zero bits in unsigned 32-bit integer “a”, and return that count in “dst”.

Intel Implementation Psudeo-Code

tmp := 0
dst := 0
DO WHILE ((tmp < 32) AND a[tmp] == 0)
        tmp := tmp + 1
        dst := dst + 1
OD

__int64 _mm_tzcnt_64(unsigned __int64 a);

Intel Description

Count the number of trailing zero bits in unsigned 64-bit integer “a”, and return that count in “dst”.

Intel Implementation Psudeo-Code

tmp := 0
dst := 0
DO WHILE ((tmp < 64) AND a[tmp] == 0)
        tmp := tmp + 1
        dst := dst + 1
OD

int _mm_popcnt_u32(unsigned int a);

Intel Description

Count the number of bits set to 1 in unsigned 32-bit integer “a”, and return that count in “dst”.

Intel Implementation Psudeo-Code

dst := 0
FOR i := 0 to 31
        IF a[i]
                dst := dst + 1
        FI
ENDFOR

__int64 _mm_popcnt_u64(unsigned __int64 a);

Intel Description

Count the number of bits set to 1 in unsigned 64-bit integer “a”, and return that count in “dst”.

Intel Implementation Psudeo-Code

dst := 0
FOR i := 0 to 63
        IF a[i]
                dst := dst + 1
        FI
ENDFOR