[src/trunk]: src/sys/arch/arm/arm Add fast path for dealing with a single 32-...

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

details:   https://anonhg.NetBSD.org/src/rev/be7f3d40f645
branches:  trunk
changeset: 783423:be7f3d40f645
user:      matt <matt%NetBSD.org@localhost>
date:      Thu Dec 20 08:03:21 2012 +0000

description:
Add fast path for dealing with a single 32-bit word at the end.

diffstat:

 sys/arch/arm/arm/cpu_in_cksum_buffer.S |  13 ++++++++-----
 1 files changed, 8 insertions(+), 5 deletions(-)

diffs (31 lines):

diff -r 099b7b5248ce -r be7f3d40f645 sys/arch/arm/arm/cpu_in_cksum_buffer.S
--- a/sys/arch/arm/arm/cpu_in_cksum_buffer.S    Thu Dec 20 07:20:04 2012 +0000
+++ b/sys/arch/arm/arm/cpu_in_cksum_buffer.S    Thu Dec 20 08:03:21 2012 +0000
@@ -29,7 +29,7 @@
 
 #include <machine/asm.h>
 
-RCSID("$NetBSD: cpu_in_cksum_buffer.S,v 1.2 2012/12/20 07:18:33 matt Exp $")
+RCSID("$NetBSD: cpu_in_cksum_buffer.S,v 1.3 2012/12/20 08:03:21 matt Exp $")
 
 /*
  * Special note:
@@ -111,11 +111,14 @@
        bne     3b                      /*   yep, do them */
 
 .Lfinal_dword:
+       ldr     r5, [r0], #4            /* load next word */
+       tst     r1, #3                  /* final amount one word exactly? */
+       beq     .Lfinal_add_one_word    /*   yes, and go add it */
        sub     r3, r1, #1              /* 0-3 = 1 word, 4-7 = 2 words */
-       tst     r3, #4                  /* more than one word more left? */
-       moveq   r4, #0                  /*   no, just use zero */
-       ldreq   r5, [r0]                /*   no, load last word */
-       ldmneia r0, {r4-r5}             /*   yes, load last dword */
+       tst     r3, #4                  /* one more word left? */
+       moveq   r4, #0                  /*   no, use 0 for 1st word  */
+       movne   r4, r5                  /*   yes, move from 2nd word to 1st */
+       ldrne   r5, [r0]                /*   yes, load last word */
 .Lfinal_dword_noload:
        rsb     r1, r1, #4              /* find out many bytes to discard */
 #ifdef __ARMEL__