Annotation of src/lib/libm/src/s_scalbnf.c, Revision 1.1
1.1 ! jtc 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: #ifndef lint
! 17: static char rcsid[] = "$Id: $";
! 18: #endif
! 19:
! 20: #include "math.h"
! 21: #include "math_private.h"
! 22:
! 23: #ifdef __STDC__
! 24: static const float
! 25: #else
! 26: static float
! 27: #endif
! 28: two25 = 3.355443200e+07, /* 0x4c000000 */
! 29: twom25 = 2.9802322388e-08, /* 0x33000000 */
! 30: huge = 1.0e+30,
! 31: tiny = 1.0e-30;
! 32:
! 33: #ifdef __STDC__
! 34: float scalbnf (float x, int n)
! 35: #else
! 36: float scalbn (x,n)
! 37: float x; int n;
! 38: #endif
! 39: {
! 40: int k,ix;
! 41: GET_FLOAT_WORD(ix,x);
! 42: k = (ix&0x7f800000)>>23; /* extract exponent */
! 43: if (k==0) { /* 0 or subnormal x */
! 44: if ((ix&0x7fffffff)==0) return x; /* +-0 */
! 45: x *= two25;
! 46: GET_FLOAT_WORD(ix,x);
! 47: k = ((ix&0x7f800000)>>23) - 25;
! 48: if (n< -50000) return tiny*x; /*underflow*/
! 49: }
! 50: if (k==0xff) return x+x; /* NaN or Inf */
! 51: k = k+n;
! 52: if (k > 0xfe) return huge*copysignf(huge,x); /* overflow */
! 53: if (k > 0) /* normal result */
! 54: {SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23)); return x;}
! 55: if (k <= -25)
! 56: if (n > 50000) /* in case integer overflow in n+k */
! 57: return huge*copysignf(huge,x); /*overflow*/
! 58: else return tiny*copysignf(tiny,x); /*underflow*/
! 59: k += 25; /* subnormal result */
! 60: SET_FLOAT_WORD(x,(ix&0x807fffff)|(k<<23));
! 61: return x*twom25;
! 62: }
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