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/**
* Not necessarily optimal... but it produces correct results (at least for int)
* If we're lucky, LLVM will recognize the pattern and produce rotate
* instructions:
* http://llvm.1065342.n5.nabble.com/rotate-td47679.html
*
* Eventually, someone should feel free to implement an llvm-specific version
*/
_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;
#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
//XXX: There's a lot of __builtin_astype calls to cast everything to
// unsigned ... This should be improved so that if GENTYPE==UGENTYPE, no
// casts are required.
UGENTYPE x_1 = __builtin_astype(x, UGENTYPE);
//XXX: Is (UGENTYPE >> SGENTYPE) | (UGENTYPE << SGENTYPE) legal?
// If so, then combine the amt and shifts into a single set of statements
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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