diff options
Diffstat (limited to 'src/math/scalbnf.c')
| -rw-r--r-- | src/math/scalbnf.c | 70 |
1 files changed, 22 insertions, 48 deletions
diff --git a/src/math/scalbnf.c b/src/math/scalbnf.c index 0a6168b0..243dafdf 100644 --- a/src/math/scalbnf.c +++ b/src/math/scalbnf.c @@ -1,54 +1,28 @@ -/* 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; + float scale; + + if (n > 127) { + x *= 0x1p127f; + n -= 127; + if (n > 127) { + x *= 0x1p127f; + n -= 127; + if (n > 127) + return x * 0x1p127f; + } + } else if (n < -126) { + x *= 0x1p-126f; + n += 126; + if (n < -126) { + x *= 0x1p-126f; + n += 126; + if (n < -126) + return x * 0x1p-126f; + } } - 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; + SET_FLOAT_WORD(scale, (uint32_t)(0x7f+n)<<23); + return x * scale; } |