lib/libm/arch/i386/e_expf.S

   1 /*
   2  * Written by J.T. Conklin <jtc@NetBSD.org>.
   3  * Public domain.
   4  *
   5  * $NetBSD: e_expf.S,v 1.5 2003/07/26 19:24:58 salo Exp $
   6  */
   7
   8 #include <machine/asm.h>
   9
  10 #include "abi.h"
  11
  12 /* e^x = 2^(x * log2(e)) */
  13 ENTRY(expf)
  14         XMM_ONE_ARG_FLOAT_PROLOGUE
  15         flds    ARG_FLOAT_ONE
  16         fldl2e
  17         fmulp                           /* x * log2(e) */
  18         fld     %st(0)
  19         frndint                         /* int(x * log2(e)) */
  20         fsubr   %st(0),%st(1)           /* fract(x * log2(e)) */
  21         fxch
  22         f2xm1                           /* 2^(fract(x * log2(e))) - 1 */
  23         fld1
  24         faddp                           /* 2^(fract(x * log2(e))) */
  25         fscale                          /* e^x */
  26         fstp    %st(1)
  27         XMM_FLOAT_EPILOGUE
  28         ret
  29 END(expf)