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Diffstat (limited to 'arch/powerpc/lib/checksum_32.S')
-rw-r--r--arch/powerpc/lib/checksum_32.S37
1 files changed, 17 insertions, 20 deletions
diff --git a/arch/powerpc/lib/checksum_32.S b/arch/powerpc/lib/checksum_32.S
index 347237253d1e..9c126028ab9c 100644
--- a/arch/powerpc/lib/checksum_32.S
+++ b/arch/powerpc/lib/checksum_32.S
@@ -27,35 +27,32 @@
* csum_partial(buff, len, sum)
*/
_GLOBAL(csum_partial)
- addic r0,r5,0
subi r3,r3,4
- srwi. r6,r4,2
+ srawi. r6,r4,2 /* Divide len by 4 and also clear carry */
beq 3f /* if we're doing < 4 bytes */
- andi. r5,r3,2 /* Align buffer to longword boundary */
+ andi. r0,r3,2 /* Align buffer to longword boundary */
beq+ 1f
- lhz r5,4(r3) /* do 2 bytes to get aligned */
- addi r3,r3,2
+ lhz r0,4(r3) /* do 2 bytes to get aligned */
subi r4,r4,2
- addc r0,r0,r5
+ addi r3,r3,2
srwi. r6,r4,2 /* # words to do */
+ adde r5,r5,r0
beq 3f
1: mtctr r6
-2: lwzu r5,4(r3) /* the bdnz has zero overhead, so it should */
- adde r0,r0,r5 /* be unnecessary to unroll this loop */
+2: lwzu r0,4(r3)
+ adde r5,r5,r0
bdnz 2b
- andi. r4,r4,3
-3: cmpwi 0,r4,2
- blt+ 4f
- lhz r5,4(r3)
+3: andi. r0,r4,2
+ beq+ 4f
+ lhz r0,4(r3)
addi r3,r3,2
- subi r4,r4,2
- adde r0,r0,r5
-4: cmpwi 0,r4,1
- bne+ 5f
- lbz r5,4(r3)
- slwi r5,r5,8 /* Upper byte of word */
- adde r0,r0,r5
-5: addze r3,r0 /* add in final carry */
+ adde r5,r5,r0
+4: andi. r0,r4,1
+ beq+ 5f
+ lbz r0,4(r3)
+ slwi r0,r0,8 /* Upper byte of word */
+ adde r5,r5,r0
+5: addze r3,r5 /* add in final carry */
blr
/*