diff options
Diffstat (limited to 'libquadmath/math/scalbnq.c')
| -rw-r--r-- | libquadmath/math/scalbnq.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/libquadmath/math/scalbnq.c b/libquadmath/math/scalbnq.c index b7049a70e45..f0852ee038d 100644 --- a/libquadmath/math/scalbnq.c +++ b/libquadmath/math/scalbnq.c @@ -13,6 +13,14 @@ * ==================================================== */ + +/* + * scalbnq (__float128 x, int n) + * scalbnq(x,n) returns x* 2**n computed by exponent + * manipulation rather than by actually performing an + * exponentiation or a multiplication. + */ + #include "quadmath-imp.h" static const __float128 @@ -34,10 +42,12 @@ scalbnq (__float128 x, int n) k = ((hx>>48)&0x7fff) - 114; } if (k==0x7fff) return x+x; /* NaN or Inf */ - k = k+n; - if (n> 50000 || k > 0x7ffe) - return huge*copysignq(huge,x); /* overflow */ if (n< -50000) return tiny*copysignq(tiny,x); /*underflow*/ + if (n> 50000 || k+n > 0x7ffe) + return huge*copysignq(huge,x); /* overflow */ + /* Now k and n are bounded we know that k = k+n does not + overflow. */ + k = k+n; if (k > 0) /* normal result */ {SET_FLT128_MSW64(x,(hx&0x8000ffffffffffffULL)|(k<<48)); return x;} if (k <= -114) |