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Commit 95551b41 authored by Raymond Toy's avatar Raymond Toy
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Rename scalbn to fdlibm_scalbn, and use a union.

parent e82e6d3b
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...@@ -31,33 +31,37 @@ huge = 1.0e+300, ...@@ -31,33 +31,37 @@ huge = 1.0e+300,
tiny = 1.0e-300; tiny = 1.0e-300;
#ifdef __STDC__ #ifdef __STDC__
double scalbn (double x, int n) double fdlibm_scalbn (double x, int n)
#else #else
double scalbn (x,n) double fdlibm_scalbn (x,n)
double x; int n; double x; int n;
#endif #endif
{ {
int k,hx,lx; int k,hx,lx;
hx = __HI(x); union { int i[2]; double d; } ux;
lx = __LO(x);
ux.d = x;
hx = ux.i[HIWORD];
lx = ux.i[LOWORD];
k = (hx&0x7ff00000)>>20; /* extract exponent */ k = (hx&0x7ff00000)>>20; /* extract exponent */
if (k==0) { /* 0 or subnormal x */ if (k==0) { /* 0 or subnormal x */
if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */ if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */
x *= two54; x *= two54;
hx = __HI(x); ux.d = x;
hx = ux.i[HIWORD];
k = ((hx&0x7ff00000)>>20) - 54; k = ((hx&0x7ff00000)>>20) - 54;
if (n< -50000) return tiny*x; /*underflow*/ if (n< -50000) return fdlibm_setexception(x, FDLIBM_UNDERFLOW);; /*underflow*/
} }
if (k==0x7ff) return x+x; /* NaN or Inf */ if (k==0x7ff) return x+x; /* NaN or Inf */
k = k+n; k = k+n;
if (k > 0x7fe) return huge*copysign(huge,x); /* overflow */ if (k > 0x7fe) return fdlibm_setexception(x, FDLIBM_OVERFLOW); /* overflow */
if (k > 0) /* normal result */ if (k > 0) /* normal result */
{__HI(x) = (hx&0x800fffff)|(k<<20); return x;} {ux.i[HIWORD] = (hx&0x800fffff)|(k<<20); return x;}
if (k <= -54) if (k <= -54)
if (n > 50000) /* in case integer overflow in n+k */ if (n > 50000) /* in case integer overflow in n+k */
return huge*copysign(huge,x); /*overflow*/ return fdlibm_setexception(x, FDLIBM_OVERFLOW); /*overflow*/
else return tiny*copysign(tiny,x); /*underflow*/ else return fdlibm_setexception(x, FDLIBM_UNDERFLOW); /*underflow*/
k += 54; /* subnormal result */ k += 54; /* subnormal result */
__HI(x) = (hx&0x800fffff)|(k<<20); ux.i[HIWORD] = (hx&0x800fffff)|(k<<20);
return x*twom54; return x*twom54;
} }
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