39 lines
753 B
ArmAsm
39 lines
753 B
ArmAsm
/*
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* Written by J.T. Conklin <jtc@netbsd.org>.
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* Public domain.
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*/
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#include <machine/asm.h>
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RCSID("$NetBSD: e_exp.S,v 1.7 1996/07/03 17:31:28 jtc Exp $")
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/* e^x = 2^(x * log2(e)) */
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ENTRY(__ieee754_exp)
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pushl %ebp
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movl %esp,%ebp
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subl $8,%esp
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fstcw -12(%ebp) /* store fpu control word */
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movw -12(%ebp),%dx
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orw $0x0180,%dx
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movw %dx,-16(%ebp)
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fldcw -16(%ebp) /* load modfied control word */
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fldl 8(%ebp)
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fldl2e
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fmulp /* x * log2(e) */
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fstl %st(1)
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frndint /* int(x * log2(e)) */
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fxch %st(1)
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fsub %st(1),%st /* fract(x * log2(e)) */
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f2xm1 /* 2^(fract(x * log2(e))) - 1 */
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fld1
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faddp /* 2^(fract(x * log2(e))) */
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fscale /* e^x */
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fstpl %st(1)
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fldcw -12(%ebp) /* restore original control word */
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leave
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ret
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