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  * $DragonFly: src/lib/libm/arch/i386/e_expf.S,v 1.1 2005/07/26 21:15:19 joerg Exp $
   7  */
   8
   9 #include <machine/asm.h>
  10
  11 #include "abi.h"
  12
  13 /* e^x = 2^(x * log2(e)) */
  14 ENTRY(expf)
  15         XMM_ONE_ARG_FLOAT_PROLOGUE
  16         flds    ARG_FLOAT_ONE
  17         fldl2e
  18         fmulp                           /* x * log2(e) */
  19         fld     %st(0)
  20         frndint                         /* int(x * log2(e)) */
  21         fsubr   %st(0),%st(1)           /* fract(x * log2(e)) */
  22         fxch
  23         f2xm1                           /* 2^(fract(x * log2(e))) - 1 */
  24         fld1
  25         faddp                           /* 2^(fract(x * log2(e))) */
  26         fscale                          /* e^x */
  27         fstp    %st(1)
  28         XMM_FLOAT_EPILOGUE
  29         ret