Function npyv__bitscan_revnz_u32

numpy/core/src/common/simd/intdiv.h:84–105

    #include <intrin.h> // _BitScanReverse
#endif
NPY_FINLINE unsigned npyv__bitscan_revnz_u32(npy_uint32 a)
{
    assert(a > 0); // due to use __builtin_clz
    unsigned r;
#if defined(NPY_HAVE_SSE2) && defined(_MSC_VER)
    unsigned long rl;
    (void)_BitScanReverse(&rl, (unsigned long)a);
    r = (unsigned)rl;

#elif defined(NPY_HAVE_SSE2) && (defined(__GNUC__) || defined(__clang__) || defined(__INTEL_COMPILER)) \
    &&  (defined(NPY_CPU_X86) || defined(NPY_CPU_AMD64))
    __asm__("bsr %1, %0" : "=r" (r) : "r"(a));
#elif defined(__GNUC__) || defined(__clang__)
    r = 31 - __builtin_clz(a); // performs on arm -> clz, ppc -> cntlzw
#else
    r = 0;
    while (a >>= 1) {
        r++;
    }
#endif
    return r;
}
NPY_FINLINE unsigned npyv__bitscan_revnz_u64(npy_uint64 a)
{
    assert(a > 0); // due to use __builtin_clzll