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38 lines
860 B
ArmAsm
38 lines
860 B
ArmAsm
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/*
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* Written by J.T. Conklin <jtc@netbsd.org>.
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* Adapted for exp2 by Ulrich Drepper <drepper@cygnus.com>.
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* Public domain.
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*/
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#include <machine/asm.h>
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ENTRY(__ieee754_exp2f)
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flds 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
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END (__ieee754_exp2f)
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