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| Rev | Author | Line No. | Line |
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| 3362 | Serge | 1 | /* |
| 2 | * ==================================================== |
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| 3 | * Copyright (C) 1998,2002 by Red Hat Inc. All rights reserved. |
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| 4 | * |
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| 5 | * Permission to use, copy, modify, and distribute this |
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| 6 | * software is freely granted, provided that this notice |
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| 7 | * is preserved. |
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| 8 | * ==================================================== |
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| 9 | */ |
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| 10 | |||
| 11 | #if !defined(_SOFT_FLOAT) |
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| 12 | |||
| 13 | /* |
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| 14 | Fast version of exp using Intel float instructions. |
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| 15 | |||
| 16 | double _f_exp (double x); |
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| 17 | |||
| 18 | Function computes e ** x. The following special cases exist: |
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| 19 | 1. if x is 0.0 ==> return 1.0 |
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| 20 | 2. if x is infinity ==> return infinity |
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| 21 | 3. if x is -infinity ==> return 0.0 |
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| 22 | 4. if x is NaN ==> return x |
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| 23 | There is no error checking or setting of errno. |
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| 24 | */ |
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| 25 | |||
| 26 | |||
| 27 | #include |
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| 28 | #include |
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| 29 | #include "f_math.h" |
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| 30 | |||
| 31 | double _f_exp (double x) |
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| 32 | { |
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| 33 | if (check_finite(x)) |
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| 34 | { |
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| 35 | double result; |
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| 36 | asm ("fldl2e; fmulp; fld %%st; frndint; fsub %%st,%%st(1); fxch;" \ |
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| 37 | "fchs; f2xm1; fld1; faddp; fxch; fld1; fscale; fstp %%st(1); fmulp" : |
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| 38 | "=t"(result) : "0"(x)); |
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| 39 | return result; |
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| 40 | } |
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| 41 | else if (x == -infinity()) |
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| 42 | return 0.0; |
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| 43 | |||
| 44 | return x; |
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| 45 | } |
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| 46 | |||
| 47 | #endif |