| 1 | /* s_ilogbf.c -- float version of s_ilogb.c. |
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| 2 | */ |
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| 3 | |
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| 4 | /* |
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| 5 | * ==================================================== |
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| 6 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
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| 7 | * |
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| 8 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
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| 9 | * Permission to use, copy, modify, and distribute this |
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| 10 | * software is freely granted, provided that this notice |
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| 11 | * is preserved. |
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| 12 | * ==================================================== |
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| 13 | */ |
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| 14 | |
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| 15 | #if defined(LIBM_SCCS) && !defined(lint) |
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| 16 | static char rcsid[] = "$NetBSD: s_ilogbf.c,v 1.4 1995/05/10 20:47:31 jtc Exp $" ; |
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| 17 | #endif |
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| 18 | |
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| 19 | #include <limits.h> |
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| 20 | #include <math.h> |
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| 21 | #include <math_private.h> |
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| 22 | |
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| 23 | int __ieee754_ilogbf(float x) |
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| 24 | { |
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| 25 | int32_t hx,ix; |
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| 26 | |
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| 27 | GET_FLOAT_WORD(hx,x); |
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| 28 | hx &= 0x7fffffff; |
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| 29 | if(hx<0x00800000) { |
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| 30 | if(hx==0) |
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| 31 | return FP_ILOGB0; /* ilogb(0) = FP_ILOGB0 */ |
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| 32 | else /* subnormal x */ |
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| 33 | for (ix = -126,hx<<=8; hx>0; hx<<=1) ix -=1; |
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| 34 | return ix; |
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| 35 | } |
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| 36 | else if (hx<0x7f800000) return (hx>>23)-127; |
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| 37 | else if (FP_ILOGBNAN != INT_MAX) { |
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| 38 | /* ISO C99 requires ilogbf(+-Inf) == INT_MAX. */ |
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| 39 | if (hx==0x7f800000) |
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| 40 | return INT_MAX; |
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| 41 | } |
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| 42 | return FP_ILOGBNAN; |
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| 43 | } |
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| 44 | |
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