forked from OSchip/llvm-project
30 lines
870 B
C++
30 lines
870 B
C++
/*
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* There are multiple formulas for calculating arccosine of x:
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* 1) acos(x) = (1/2*pi) + i * ln(i*x + sqrt(1-x^2)) (notice the 'i'...)
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* 2) acos(x) = pi/2 + asin(-x) (asin isn't implemented yet)
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* 3) acos(x) = pi/2 - asin(x) (ditto)
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* 4) acos(x) = 2*atan2(sqrt(1-x), sqrt(1+x))
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* 5) acos(x) = pi/2 - atan2(x, ( sqrt(1-x^2) ) )
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*
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* Options 1-3 are not currently usable, #5 generates more concise radeonsi
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* bitcode and assembly than #4 (134 vs 132 instructions on radeonsi), but
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* precision of #4 may be better.
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*/
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#if __CLC_FPSIZE == 32
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#define __CLC_CONST(x) x ## f
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#else
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#define __CLC_CONST(x) x
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#endif
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_CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE acos(__CLC_GENTYPE x) {
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return (
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(__CLC_GENTYPE) __CLC_CONST(2.0) * atan2(
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sqrt((__CLC_GENTYPE) __CLC_CONST(1.0) - x),
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sqrt((__CLC_GENTYPE) __CLC_CONST(1.0) + x)
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)
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);
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}
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#undef __CLC_CONST
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