diff options
Diffstat (limited to 'compiler-rt/lib/builtins/clzsi2.c')
-rw-r--r-- | compiler-rt/lib/builtins/clzsi2.c | 62 |
1 files changed, 30 insertions, 32 deletions
diff --git a/compiler-rt/lib/builtins/clzsi2.c b/compiler-rt/lib/builtins/clzsi2.c index fe06f065b00..90dc82d08ef 100644 --- a/compiler-rt/lib/builtins/clzsi2.c +++ b/compiler-rt/lib/builtins/clzsi2.c @@ -17,36 +17,34 @@ /* Precondition: a != 0 */ -COMPILER_RT_ABI si_int -__clzsi2(si_int a) -{ - su_int x = (su_int)a; - si_int t = ((x & 0xFFFF0000) == 0) << 4; /* if (x is small) t = 16 else 0 */ - x >>= 16 - t; /* x = [0 - 0xFFFF] */ - su_int r = t; /* r = [0, 16] */ - /* return r + clz(x) */ - t = ((x & 0xFF00) == 0) << 3; - x >>= 8 - t; /* x = [0 - 0xFF] */ - r += t; /* r = [0, 8, 16, 24] */ - /* return r + clz(x) */ - t = ((x & 0xF0) == 0) << 2; - x >>= 4 - t; /* x = [0 - 0xF] */ - r += t; /* r = [0, 4, 8, 12, 16, 20, 24, 28] */ - /* return r + clz(x) */ - t = ((x & 0xC) == 0) << 1; - x >>= 2 - t; /* x = [0 - 3] */ - r += t; /* r = [0 - 30] and is even */ - /* return r + clz(x) */ -/* switch (x) - * { - * case 0: - * return r + 2; - * case 1: - * return r + 1; - * case 2: - * case 3: - * return r; - * } - */ - return r + ((2 - x) & -((x & 2) == 0)); +COMPILER_RT_ABI si_int __clzsi2(si_int a) { + su_int x = (su_int)a; + si_int t = ((x & 0xFFFF0000) == 0) << 4; /* if (x is small) t = 16 else 0 */ + x >>= 16 - t; /* x = [0 - 0xFFFF] */ + su_int r = t; /* r = [0, 16] */ + /* return r + clz(x) */ + t = ((x & 0xFF00) == 0) << 3; + x >>= 8 - t; /* x = [0 - 0xFF] */ + r += t; /* r = [0, 8, 16, 24] */ + /* return r + clz(x) */ + t = ((x & 0xF0) == 0) << 2; + x >>= 4 - t; /* x = [0 - 0xF] */ + r += t; /* r = [0, 4, 8, 12, 16, 20, 24, 28] */ + /* return r + clz(x) */ + t = ((x & 0xC) == 0) << 1; + x >>= 2 - t; /* x = [0 - 3] */ + r += t; /* r = [0 - 30] and is even */ + /* return r + clz(x) */ + /* switch (x) + * { + * case 0: + * return r + 2; + * case 1: + * return r + 1; + * case 2: + * case 3: + * return r; + * } + */ + return r + ((2 - x) & -((x & 2) == 0)); } |