1/* 2 * Written by J.T. Conklin <jtc@netbsd.org>. 3 * Adapted for exp2 by Ulrich Drepper <drepper@cygnus.com>. 4 * Public domain. 5 */ 6 7#include <machine/asm.h> 8 9ENTRY(__ieee754_exp2f) 10 flds 4(%esp) 11/* I added the following ugly construct because exp(+-Inf) resulted 12 in NaN. The ugliness results from the bright minds at Intel. 13 For the i686 the code can be written better. 14 -- drepper@cygnus.com. */ 15 fxam /* Is NaN or +-Inf? */ 16 fstsw %ax 17 movb $0x45, %dh 18 andb %ah, %dh 19 cmpb $0x05, %dh 20 je 1f /* Is +-Inf, jump. */ 21 fld %st 22 frndint /* int(x) */ 23 fsubr %st,%st(1) /* fract(x) */ 24 fxch 25 f2xm1 /* 2^(fract(x)) - 1 */ 26 fld1 27 faddp /* 2^(fract(x)) */ 28 fscale /* e^x */ 29 fstp %st(1) 30 ret 31 321: testl $0x200, %eax /* Test sign. */ 33 jz 2f /* If positive, jump. */ 34 fstp %st 35 fldz /* Set result to 0. */ 362: ret 37END (__ieee754_exp2f) 38