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Diffstat (limited to 'src/math/scalbnf.c')
| -rw-r--r-- | src/math/scalbnf.c | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/src/math/scalbnf.c b/src/math/scalbnf.c new file mode 100644 index 00000000..0a6168b0 --- /dev/null +++ b/src/math/scalbnf.c @@ -0,0 +1,54 @@ +/* origin: FreeBSD /usr/src/lib/msun/src/s_scalbnf.c */ +/* + * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. + */ +/* + * ==================================================== + * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. + * + * Developed at SunPro, a Sun Microsystems, Inc. business. + * Permission to use, copy, modify, and distribute this + * software is freely granted, provided that this notice + * is preserved. + * ==================================================== + */ + +#include "libm.h" + +static const float +two25 = 3.355443200e+07, /* 0x4c000000 */ +twom25 = 2.9802322388e-08, /* 0x33000000 */ +huge = 1.0e+30, +tiny = 1.0e-30; + +float scalbnf(float x, int n) +{ + int32_t k, ix; + GET_FLOAT_WORD(ix, x); + k = (ix&0x7f800000)>>23; /* extract exponent */ + if (k == 0) { /* 0 or subnormal x */ + if ((ix&0x7fffffff) == 0) /* +-0 */ + return x; + x *= two25; + GET_FLOAT_WORD(ix, x); + k = ((ix&0x7f800000)>>23) - 25; + if (n < -50000) + return tiny*x; /*underflow*/ + } + if (k == 0xff) /* NaN or Inf */ + return x + x; + k = k + n; + if (k > 0xfe) + return huge*copysignf(huge, x); /* overflow */ + if (k > 0) { /* normal result */ + SET_FLOAT_WORD(x, (ix&0x807fffff)|(k<<23)); + return x; + } + if (k <= -25) + if (n > 50000) /* in case integer overflow in n+k */ + return huge*copysignf(huge,x); /*overflow*/ + return tiny*copysignf(tiny, x); /*underflow*/ + k += 25; /* subnormal result */ + SET_FLOAT_WORD(x, (ix&0x807fffff)|(k<<23)); + return x*twom25; +} |