[src/trunk]: src/sys/arch/mac68k/mac68k Tweak previous: use shorter instruct...

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

details:   https://anonhg.NetBSD.org/src/rev/3b8463c52d6b
branches:  trunk
changeset: 473616:3b8463c52d6b
user:      scottr <scottr%NetBSD.org@localhost>
date:      Wed Jun 09 15:34:08 1999 +0000

description:
Tweak previous:  use shorter instructions to accomplish the same
#task (minimizes overhead).

diffstat:

 sys/arch/mac68k/mac68k/locore.s |  27 +++++++++++++++------------
 1 files changed, 15 insertions(+), 12 deletions(-)

diffs (44 lines):

diff -r 4a49f40ad1a1 -r 3b8463c52d6b sys/arch/mac68k/mac68k/locore.s
--- a/sys/arch/mac68k/mac68k/locore.s   Wed Jun 09 12:38:50 1999 +0000
+++ b/sys/arch/mac68k/mac68k/locore.s   Wed Jun 09 15:34:08 1999 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: locore.s,v 1.115 1999/06/09 06:59:53 scottr Exp $      */
+/*     $NetBSD: locore.s,v 1.116 1999/06/09 15:34:08 scottr Exp $      */
 
 /*
  * Copyright (c) 1988 University of Utah.
@@ -1499,20 +1499,23 @@
  * the loops will run from a single cache half-line.
  */
        .align  8                       | align to half-line boundary
+       nop                             | pad to align Ldelay
+       nop
+       nop
 ENTRY(_delay)
-       movl    sp@(4),d0
-       jeq     Ldelayexit
-       movl    d0,d1
-       andl    #0xffff,d0
-       swap    d1
-       subql   #1,d0
-       andl    #0xffff,d1
+       movl    sp@(4),d0               | get iterations
+       jeq     Ldelayexit              | bail out if nothing to do
+       movql   #0,d1                   | put bits 15-0 in d1 for the
+       movw    d0,d1                   |   inner loop, and move bits
+       movw    #0,d0                   |   31-16 to the low-order word
+       subql   #1,d1                   |   of d0 for the outer loop
+       swap    d0
 Ldelay:
-       tstl    _C_LABEL(delay_flag)
+       tstl    _C_LABEL(delay_flag)    | this never changes for delay()!
+       dbeq    d1,Ldelay               |   (used only for timing purposes)
        dbeq    d0,Ldelay
-       dbeq    d1,Ldelay
-       addql   #1,d0
-       swap    d1
+       addqw   #1,d1                   | adjust end count and
+       swap    d0                      |    return the longword result
        orl     d1,d0
 Ldelayexit:
        rts