diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/msun/i387/e_exp.S | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/lib/msun/i387/e_exp.S b/lib/msun/i387/e_exp.S index d21958c..9c87407 100644 --- a/lib/msun/i387/e_exp.S +++ b/lib/msun/i387/e_exp.S @@ -51,9 +51,10 @@ ENTRY(exp) fldl 4(%esp) /* - * Ensure that the rounding mode is to nearest (to give the smallest - * possible fraction) and that the precision is as high as possible. - * We may as well mask interrupts if we switch the mode. + * Extended precision is needed to reduce the maximum error from + * hundreds of ulps to less than 1 ulp. Switch to it if necessary. + * We may as well set the rounding mode to to-nearest and mask traps + * if we switch. */ fstcw 4(%esp) movl 4(%esp),%eax @@ -81,8 +82,9 @@ ENTRY(exp) x_Inf_or_NaN: /* - * Return 0 if x is -Inf. Otherwise just return x, although the - * C version would return (x + x) (Real Indefinite) if x is a NaN. + * Return 0 if x is -Inf. Otherwise just return x; when x is Inf + * this gives Inf, and when x is a NaN this gives the same result + * as (x + x) (x quieted). */ cmpl $0xfff00000,8(%esp) jne x_not_minus_Inf |
