diff options
Diffstat (limited to 'generic/lib/integer/rotate.inc')
-rw-r--r-- | generic/lib/integer/rotate.inc | 42 |
1 files changed, 21 insertions, 21 deletions
diff --git a/generic/lib/integer/rotate.inc b/generic/lib/integer/rotate.inc index e83dd51..7792a97 100644 --- a/generic/lib/integer/rotate.inc +++ b/generic/lib/integer/rotate.inc @@ -11,25 +11,25 @@ _CLC_OVERLOAD _CLC_DEF GENTYPE rotate(GENTYPE x, GENTYPE n){ //Try to avoid extra work if someone's spinning the value through multiple //full rotations n = n % (GENTYPE)GENSIZE; - - //Determine if we're doing a right or left shift on each component - //The actual shift algorithm is based on a rotate right - //e.g. a rotate of int by 5 bits becomes rotate right by 26 bits - // and a rotate of int by -4 bits becomes rotate right by 4 - GENTYPE amt = (n > (GENTYPE)0 ? (GENTYPE)GENSIZE - n : (GENTYPE)0 - n ); - - //Calculate the bits that will wrap - GENTYPE mask = ( (GENTYPE)1 << amt ) - (GENTYPE)1; - GENTYPE wrapped_bits = x & mask; - - //Shift the input value right and then AND a mask that eliminates - //sign-extension interference - //if the rotate amount is 0, just use ~0 for a mask - GENTYPE se_mask = !amt ? ~((GENTYPE)0) : - ( ( (GENTYPE)1 << ((GENTYPE)GENSIZE - amt) ) - (GENTYPE)1 ); - GENTYPE unwrapped_bits = x >> amt; - unwrapped_bits &= se_mask; - - //Finally shift the input right after moving the wrapped bits into position - return unwrapped_bits | (wrapped_bits << ( (GENTYPE)GENSIZE - amt ) ); + +#ifdef SCALAR + if (n > 0){ + return (x << n) | (((UGENTYPE)x) >> (GENSIZE - n)); + } else if (n == 0){ + return x; + } else { + return ( (((UGENTYPE)x) >> -n) | (x << (GENSIZE + n)) ); + } +#else + UGENTYPE x_1 = __builtin_astype(x, UGENTYPE); + + UGENTYPE amt; + amt = (n < (GENTYPE)0 ? __builtin_astype((GENTYPE)0-n, UGENTYPE) : (UGENTYPE)0); + x_1 = (x_1 >> amt) | (x_1 << ((UGENTYPE)GENSIZE - amt)); + + amt = (n < (GENTYPE)0 ? (UGENTYPE)0 : __builtin_astype(n, UGENTYPE)); + x_1 = (x_1 << amt) | (x_1 >> ((UGENTYPE)GENSIZE - amt)); + + return __builtin_astype(x_1, GENTYPE); +#endif }
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