| 1 | /* s_logbf.c -- float version of s_logb.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 | #include <math.h> |
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| 16 | #include <math_private.h> |
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| 17 | #include <libm-alias-float.h> |
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| 18 | #include <fix-int-fp-convert-zero.h> |
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| 19 | #include <math-use-builtins.h> |
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| 20 | |
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| 21 | float |
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| 22 | __logbf (float x) |
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| 23 | { |
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| 24 | #if USE_LOGBF_BUILTIN |
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| 25 | return __builtin_logbf (x); |
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| 26 | #else |
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| 27 | int32_t ix, rix; |
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| 28 | |
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| 29 | GET_FLOAT_WORD (ix, x); |
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| 30 | ix &= 0x7fffffff; /* high |x| */ |
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| 31 | if (ix == 0) |
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| 32 | return (float) -1.0 / fabsf (x: x); |
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| 33 | if (ix >= 0x7f800000) |
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| 34 | return x * x; |
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| 35 | if (__glibc_unlikely ((rix = ix >> 23) == 0)) |
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| 36 | { |
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| 37 | /* POSIX specifies that denormal number is treated as |
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| 38 | though it were normalized. */ |
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| 39 | rix -= __builtin_clz (ix) - 9; |
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| 40 | } |
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| 41 | if (FIX_INT_FP_CONVERT_ZERO && rix == 127) |
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| 42 | return 0.0f; |
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| 43 | return (float) (rix - 127); |
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| 44 | #endif /* ! USE_LOGBF_BUILTIN */ |
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| 45 | } |
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| 46 | libm_alias_float (__logb, logb) |
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| 47 | |
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