[src/trunk]: src/sys/arch/m68k/fpe exp(>11356) is +inf even if extended preci...

[isaki <isaki%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/49cda9fbe95b
branches:  trunk
changeset: 820794:49cda9fbe95b
user:      isaki <isaki%NetBSD.org@localhost>
date:      Sun Jan 15 11:56:11 2017 +0000

description:
exp(>11356) is +inf even if extended precision.
exp(<-11401) is 0 even if extended precision.

diffstat:

 sys/arch/m68k/fpe/fpu_exp.c |  32 ++++++++++++++++++--------------
 1 files changed, 18 insertions(+), 14 deletions(-)

diffs (67 lines):

diff -r f5467b163dca -r 49cda9fbe95b sys/arch/m68k/fpe/fpu_exp.c
--- a/sys/arch/m68k/fpe/fpu_exp.c       Sun Jan 15 11:46:21 2017 +0000
+++ b/sys/arch/m68k/fpe/fpu_exp.c       Sun Jan 15 11:56:11 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: fpu_exp.c,v 1.10 2016/12/07 11:27:18 isaki Exp $       */
+/*     $NetBSD: fpu_exp.c,v 1.11 2017/01/15 11:56:11 isaki Exp $       */
 
 /*
  * Copyright (c) 1995  Ken Nakata
@@ -32,7 +32,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: fpu_exp.c,v 1.10 2016/12/07 11:27:18 isaki Exp $");
+__KERNEL_RCSID(0, "$NetBSD: fpu_exp.c,v 1.11 2017/01/15 11:56:11 isaki Exp $");
 
 #include <machine/ieee.h>
 
@@ -109,7 +109,7 @@
 fpu_etox(struct fpemu *fe)
 {
        struct fpn x, *fp;
-       int j, k;
+       int k;
 
        if (ISNAN(&fe->fe_f2))
                return &fe->fe_f2;
@@ -119,6 +119,20 @@
                return &fe->fe_f2;
        }
 
+       /*
+        * return inf if x >=  2^14
+        * return +0  if x <= -2^14
+        */
+       if (fe->fe_f2.fp_exp >= 14) {
+               if (fe->fe_f2.fp_sign) {
+                       fe->fe_f2.fp_class = FPC_ZERO;
+                       fe->fe_f2.fp_sign = 0;
+               } else {
+                       fe->fe_f2.fp_class = FPC_INF;
+               }
+               return &fe->fe_f2;
+       }
+
        CPYFPN(&x, &fe->fe_f2);
 
        /* k = round(x / ln2) */
@@ -134,17 +148,7 @@
                return fp;
        }
        /* extract k as integer format from fpn format */
-       j = FP_LG - fp->fp_exp;
-       if (j < 0) {
-               if (fp->fp_sign) {
-                       fp->fp_class = FPC_ZERO;                /* k < -2^18 */
-                       fp->fp_sign = 0;
-               } else {
-                       fp->fp_class = FPC_INF;                 /* k >  2^18 */
-               }
-               return fp;
-       }
-       k = fp->fp_mant[0] >> j;
+       k = fp->fp_mant[0] >> (FP_LG - fp->fp_exp);
        if (fp->fp_sign)
                k *= -1;