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improve granularity of custom compat_ctz

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This commit is contained in:
Jamiras 2021-01-21 23:29:58 -07:00
parent 78ab9853a7
commit 98ea2b6a47
1 changed files with 25 additions and 11 deletions
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36
libretro-common/include/compat/intrinsics.h
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@ -66,17 +66,31 @@ static INLINE int compat_ctz(unsigned x)
_BitScanForward((unsigned long*)&r, x);
return (int)r;
#else
/* Only checks at nibble granularity,
* because that's what we need. */
if (x & 0x000f)
return 0;
if (x & 0x00f0)
return 4;
if (x & 0x0f00)
return 8;
if (x & 0xf000)
return 12;
return 16;
int count = 0;
if (!(x & 0xffff))
{
x >>= 16;
count |= 16;
}
if (!(x & 0xff))
{
x >>= 8;
count |= 8;
}
if (!(x & 0xf))
{
x >>= 4;
count |= 4;
}
if (!(x & 0x3))
{
x >>= 2;
count |= 2;
}
if (!(x & 0x1))
count |= 1;
return count;
#endif
}