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* Tried to do something with cucul_powf. It currently sucks.

tags/v0.99.beta14
Sam Hocevar sam 18 年之前
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382e1148ff
共有 1 個文件被更改,包括 23 次插入13 次删除
  1. +23
    -13
      cucul/math.c

+ 23
- 13
cucul/math.c 查看文件

@@ -70,26 +70,36 @@ unsigned int cucul_sqrt(unsigned int a)
return 2 * cucul_sqrt(a / 4);
}


/**
* \brief powf substitute (x^y)
* \param x The value to be raised
* \param y The power to raise x of.
* \param y The power to raise x to (only works with integers)
* \return \p x raised to the power of \p y
*/

float cucul_powf(float x, float y)
{
int i=((int)y);
float r=x;
#ifdef __i386__
/* FIXME: this can be optimised by directly calling fyl2x for x and y */
register double logx;
register long double v, e;

if(((int)y)==1 || ((int)x)==1)
return x;
asm volatile("fldln2; fxch; fyl2x"
: "=t" (logx) : "0" (x) : "st(1)");

i--;
while(i--)
{
r*=x;
}
return r;
asm volatile("fldl2e\n\t"
"fmul %%st(1)\n\t"
"fst %%st(1)\n\t"
"frndint\n\t"
"fxch\n\t"
"fsub %%st(1)\n\t"
"f2xm1\n\t"
: "=t" (v), "=u" (e) : "0" (y * logx));
v += 1.0;
asm volatile("fscale"
: "=t" (v) : "0" (v), "u" (e));

return v;
#else
return x; /* HAHAHA VIEUX PORC */
#endif
}

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