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serge |
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/* |
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* Written by J.T. Conklin . |
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* Adapted for exp2 by Ulrich Drepper . |
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* Public domain. |
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*/ |
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.file "exp2.S" |
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.text |
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.align 4 |
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.globl _exp2 |
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.def _exp2; .scl 2; .type 32; .endef |
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_exp2: |
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fldl 4(%esp) |
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/* I added the following ugly construct because exp(+-Inf) resulted |
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in NaN. The ugliness results from the bright minds at Intel. |
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For the i686 the code can be written better. |
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-- drepper@cygnus.com. */ |
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fxam /* Is NaN or +-Inf? */ |
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fstsw %ax |
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movb $0x45, %dh |
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andb %ah, %dh |
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cmpb $0x05, %dh |
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je 1f /* Is +-Inf, jump. */ |
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fld %st |
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frndint /* int(x) */ |
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fsubr %st,%st(1) /* fract(x) */ |
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fxch |
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f2xm1 /* 2^(fract(x)) - 1 */ |
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fld1 |
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faddp /* 2^(fract(x)) */ |
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fscale /* e^x */ |
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fstp %st(1) |
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ret |
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1: testl $0x200, %eax /* Test sign. */ |
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jz 2f /* If positive, jump. */ |
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fstp %st |
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fldz /* Set result to 0. */ |
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2: ret |