[src/trunk]: src/lib/libc/arch/i386/gen add a simpler version

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

details:   https://anonhg.NetBSD.org/src/rev/bba9326cd26c
branches:  trunk
changeset: 769999:bba9326cd26c
user:      christos <christos%NetBSD.org@localhost>
date:      Thu Sep 29 22:46:00 2011 +0000

description:
add a simpler version

diffstat:

 lib/libc/arch/i386/gen/flt_rounds.S |  39 ++++++++++++------------------------
 1 files changed, 13 insertions(+), 26 deletions(-)

diffs (50 lines):

diff -r f4950de8fa4f -r bba9326cd26c lib/libc/arch/i386/gen/flt_rounds.S
--- a/lib/libc/arch/i386/gen/flt_rounds.S       Thu Sep 29 22:45:20 2011 +0000
+++ b/lib/libc/arch/i386/gen/flt_rounds.S       Thu Sep 29 22:46:00 2011 +0000
@@ -1,33 +1,20 @@
-/*     $NetBSD: flt_rounds.S,v 1.6 1999/08/23 08:45:09 kleink Exp $    */
-
-/*
- * Written by J.T. Conklin, Apr 4, 1995
- * Public domain.
- */
+/*     $NetBSD: flt_rounds.S,v 1.7 2011/09/29 22:46:00 christos Exp $  */
 
 #include <machine/asm.h>
 
+/*
+ * 00 0 round to zero 
+ * 01 1 round to nearest
+ * 10 2 round to positive infinity
+ * 11 3 round to negative infinity
+ */
        .text
        _ALIGN_TEXT
-_map:
-       .byte 1         /* round to nearest */
-       .byte 3         /* round to negative infinity */
-       .byte 2         /* round to positive infinity */
-       .byte 0         /* round to zero */
-
 ENTRY(__flt_rounds)
-       subl $4,%esp
-       fnstcw (%esp)
-       movl (%esp),%eax
-       shrl $10,%eax
-       andl $3,%eax
-#ifdef PIC
-       PIC_PROLOGUE
-       leal PIC_GOTOFF(_map),%ecx
-       PIC_EPILOGUE
-       movb (%ecx,%eax,1),%al
-#else
-       movb _map(,%eax,1),%al
-#endif
-       addl $4,%esp
+       fnstcw  -4(%esp)
+       movl    -4(%esp), %ecx
+       shrl    $9, %ecx
+       andl    $6, %ecx
+       xorl    $1, %eax        /* map 0,1,2,3 -> 1,0,3,2 */
+       andl    $3, %eax
        ret