[src/trunk]: src/lib/libc/arch/powerpc/gen Update FPSCR_FX consistently per t...

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

details:   https://anonhg.NetBSD.org/src/rev/8eaf60c2694b
branches:  trunk
changeset: 565348:8eaf60c2694b
user:      matt <matt%NetBSD.org@localhost>
date:      Sun Apr 04 19:54:05 2004 +0000

description:
Update FPSCR_FX consistently per the Programming Environment Manual.  So
if any sticky bit is set, FPSCR_FX should be set.  If no sticky bits are
set, then FPSCR_FX should be clear.

diffstat:

 lib/libc/arch/powerpc/gen/fpsetsticky.c |  18 +++++++++++++-----
 1 files changed, 13 insertions(+), 5 deletions(-)

diffs (40 lines):

diff -r c8e8a8c3d12b -r 8eaf60c2694b lib/libc/arch/powerpc/gen/fpsetsticky.c
--- a/lib/libc/arch/powerpc/gen/fpsetsticky.c   Sun Apr 04 19:31:19 2004 +0000
+++ b/lib/libc/arch/powerpc/gen/fpsetsticky.c   Sun Apr 04 19:54:05 2004 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: fpsetsticky.c,v 1.5 2004/04/04 19:31:19 matt Exp $     */
+/*     $NetBSD: fpsetsticky.c,v 1.6 2004/04/04 19:54:05 matt Exp $     */
 
 /*
  * Copyright (c) 1999 The NetBSD Foundation, Inc.
@@ -63,18 +63,26 @@
        __asm__ __volatile("mffs %0" : "=f"(fpscr));
        old = ((uint32_t)fpscr & STICKYBITS) >> STICKYSHFT;
        /*
-        * FPSCR_VX (aka FP_X_INV) is not a sticky bit but a summary
-        * of the all the FPSCR_VX* sticky bits.  So FP_X_INV is cleared
+        * FPSCR_VX (aka FP_X_INV) is not a sticky bit but a summary of the
+        * all the FPSCR_VX* sticky bits.  So when FP_X_INV is cleared then
         * clear all of those bits, likewise when it's set, set them all.
         */
        if ((mask & FP_X_INV) == 0)
                fpscr &= ~INVBITS;
        else 
                fpscr |= INVBITS;
-       if (mask == 0)
-               fpscr &= ~FPSCR_FX;
        fpscr &= ~STICKYBITS;
        fpscr |= ((uint32_t)mask << STICKYSHFT) & STICKYBITS;
+       /*
+        * Make FPSCR_FX reflect the presence of a set sticky bit (or not).
+        */
+       if (fpscr & (STICKYBITS|INVBITS))
+               fpscr |= FPSCR_FX;
+       else
+               fpscr &= ~FPSCR_FX;
+       /*
+        * Write back the fpscr.
+        */
        __asm__ __volatile("mtfsf 0xff,%0" :: "f"(fpscr));
        return (old);
 }