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Diffstat (limited to 'sysdeps/libm-i387/e_expl.S')
| -rw-r--r-- | sysdeps/libm-i387/e_expl.S | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/sysdeps/libm-i387/e_expl.S b/sysdeps/libm-i387/e_expl.S new file mode 100644 index 0000000..d140898 --- /dev/null +++ b/sysdeps/libm-i387/e_expl.S @@ -0,0 +1,40 @@ +/* + * Written by J.T. Conklin <jtc@netbsd.org>. + * Public domain. + * + * Adapted for `long double' by Ulrich Drepper <drepper@cygnus.com>. + */ + +#include <machine/asm.h> + +RCSID("$NetBSD: $") + +/* e^x = 2^(x * log2l(e)) */ +ENTRY(__ieee754_expl) + fldt 4(%esp) +/* I added the following ugly construct because expl(+-Inf) resulted + in NaN. The ugliness results from the bright minds at Intel. + -- drepper@cygnus.com. */ + fxam /* Is NaN or +-Inf? */ + fstsw %ax + sahf + jnc .LnoInfNaN /* No, jump. */ + jp .LisInf /* Is +-Inf, jump. */ +.LnoInfNaN: + fldl2e + fmulp /* x * log2(e) */ + fstl %st(1) + frndint /* int(x * log2(e)) */ + fstl %st(2) + fsubrp /* fract(x * log2(e)) */ + f2xm1 /* 2^(fract(x * log2(e))) - 1 */ + fld1 + faddp /* 2^(fract(x * log2(e))) */ + fscale /* e^x */ + ret + +.LisInf: + andb $2, %ah /* Test sign. */ + jz .LpInf /* If positive, jump. */ + fldz /* Set result to 0. */ +.LpInf: ret |