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e_exp.S revision 1.6 
      1  1.1  jtc /*
      2  1.3  jtc  * Written by J.T. Conklin <jtc (at) netbsd.org>.
      3  1.3  jtc  * Public domain.
      4  1.1  jtc  */
      5  1.1  jtc 
      6  1.1  jtc #include <machine/asm.h>
      7  1.1  jtc 
      8  1.6  jtc RCSID("$NetBSD: e_exp.S,v 1.6 1996/07/03 17:27:34 jtc Exp $")
      9  1.2  jtc 
     10  1.1  jtc /* e^x = 2^(x * log2(e)) */
     11  1.1  jtc ENTRY(__ieee754_exp)
     12  1.6  jtc 	pushl	%ebp
     13  1.6  jtc 	movl	%esp,%ebp
     14  1.6  jtc 	subl	$8,%esp
     15  1.6  jtc 
     16  1.6  jtc 	fstcw	-12(%ebp)		/* store fpu control word */
     17  1.6  jtc 	movw	-12(%ebp),%dx
     18  1.6  jtc 	orw	$0x0180,%dx
     19  1.6  jtc 	movw	%dx,-16(%ebp)
     20  1.6  jtc 	fldcw	-16(%ebp)		/* load modfied control word */
     21  1.6  jtc 
     22  1.6  jtc 	fldl	8(%ebp)
     23  1.1  jtc 	fldl2e
     24  1.1  jtc 	fmulp				/* x * log2(e) */
     25  1.1  jtc 	fstl	%st(1)
     26  1.1  jtc 	frndint				/* int(x * log2(e)) */
     27  1.1  jtc 	fstl	%st(2)
     28  1.1  jtc 	fsubrp				/* fract(x * log2(e)) */
     29  1.1  jtc 	f2xm1				/* 2^(fract(x * log2(e))) - 1 */
     30  1.1  jtc 	fld1
     31  1.1  jtc 	faddp				/* 2^(fract(x * log2(e))) */
     32  1.1  jtc 	fscale				/* e^x */
     33  1.5  jtc 	fstpl	%st(1)
     34  1.6  jtc 
     35  1.6  jtc 	fldcw	-12(%ebp)		/* restore original control word */
     36  1.6  jtc 
     37  1.6  jtc 	leave
     38  1.1  jtc 	ret
     39