1 /* s_scalbnf.c -- float version of s_scalbn.c. 2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 3 */ 4 5 /* 6 * ==================================================== 7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 8 * 9 * Developed at SunPro, a Sun Microsystems, Inc. business. 10 * Permission to use, copy, modify, and distribute this 11 * software is freely granted, provided that this notice 12 * is preserved. 13 * ==================================================== 14 */ 15 16 #include <sys/cdefs.h> 17 #if defined(LIBM_SCCS) && !defined(lint) 18 __RCSID("$NetBSD: s_scalbnf.c,v 1.10 2013/01/28 06:34:09 matt Exp $"); 19 #endif 20 21 #include "namespace.h" 22 #include "math.h" 23 #include "math_private.h" 24 25 #ifndef _LP64 26 __strong_alias(_scalbnf, _scalblnf) 27 #endif 28 __weak_alias(scalbnf, _scalbnf) 29 __weak_alias(scalblnf, _scalblnf) 30 31 static const float 32 two25 = 0x1.0p25, /* 0x4c000000 */ 33 twom25 = 0x1.0p-25, /* 0x33000000 */ 34 huge = 1.0e+30, 35 tiny = 1.0e-30; 36 37 #ifdef _LP64 38 float 39 scalbnf(float x, int n) 40 { 41 return scalblnf(x, n); 42 } 43 #endif 44 45 float 46 scalblnf(float x, long n) 47 { 48 int32_t k,ix; 49 GET_FLOAT_WORD(ix,x); 50 k = (ix&0x7f800000)>>23; /* extract exponent */ 51 if (k==0) { /* 0 or subnormal x */ 52 if ((ix&0x7fffffff)==0) return x; /* +-0 */ 53 x *= two25; 54 GET_FLOAT_WORD(ix,x); 55 k = ((ix&0x7f800000)>>23) - 25; 56 if (n< -50000) return tiny*x; /*underflow*/ 57 } 58 if (k==0xff) return x+x; /* NaN or Inf */ 59 k = k+n; 60 if (k > 0xfe) return huge*copysignf(huge,x); /* overflow */ 61 if (k > 0) /* normal result */ 62 {SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x;} 63 if (k <= -25) { 64 if (n > 50000) /* in case integer overflow in n+k */ 65 return huge*copysignf(huge,x); /*overflow*/ 66 else return tiny*copysignf(tiny,x); /*underflow*/ 67 } 68 k += 25; /* subnormal result */ 69 SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); 70 return x*twom25; 71 } 72