summaryrefslogtreecommitdiff
path: root/arch/cris/arch-v32/lib/checksum.S
diff options
context:
space:
mode:
authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /arch/cris/arch-v32/lib/checksum.S
Initial import
Diffstat (limited to 'arch/cris/arch-v32/lib/checksum.S')
-rw-r--r--arch/cris/arch-v32/lib/checksum.S88
1 files changed, 88 insertions, 0 deletions
diff --git a/arch/cris/arch-v32/lib/checksum.S b/arch/cris/arch-v32/lib/checksum.S
new file mode 100644
index 000000000..4a72a94a4
--- /dev/null
+++ b/arch/cris/arch-v32/lib/checksum.S
@@ -0,0 +1,88 @@
+/*
+ * A fast checksum routine using movem
+ * Copyright (c) 1998-2007 Axis Communications AB
+ *
+ * csum_partial(const unsigned char * buff, int len, unsigned int sum)
+ */
+
+ .globl csum_partial
+ .type csum_partial,@function
+csum_partial:
+
+ ;; r10 - src
+ ;; r11 - length
+ ;; r12 - checksum
+
+ ;; Optimized for large packets
+ subq 10*4, $r11
+ blt _word_loop
+ move.d $r11, $acr
+
+ subq 9*4,$sp
+ clearf c
+ movem $r8,[$sp]
+
+ ;; do a movem checksum
+
+_mloop: movem [$r10+],$r9 ; read 10 longwords
+ ;; Loop count without touching the c flag.
+ addoq -10*4, $acr, $acr
+ ;; perform dword checksumming on the 10 longwords
+
+ addc $r0,$r12
+ addc $r1,$r12
+ addc $r2,$r12
+ addc $r3,$r12
+ addc $r4,$r12
+ addc $r5,$r12
+ addc $r6,$r12
+ addc $r7,$r12
+ addc $r8,$r12
+ addc $r9,$r12
+
+ ;; test $acr without trashing carry.
+ move.d $acr, $acr
+ bpl _mloop
+ ;; r11 <= acr is not really needed in the mloop, just using the dslot
+ ;; to prepare for what is needed after mloop.
+ move.d $acr, $r11
+
+ ;; fold the last carry into r13
+ addc 0, $r12
+ movem [$sp+],$r8 ; restore regs
+
+_word_loop:
+ addq 10*4,$r11 ; compensate for last loop underflowing length
+
+ moveq -1,$r9 ; put 0xffff in r9, faster than move.d 0xffff,r9
+ lsrq 16,$r9
+
+ move.d $r12,$r13
+ lsrq 16,$r13 ; r13 = checksum >> 16
+ and.d $r9,$r12 ; checksum = checksum & 0xffff
+
+_no_fold:
+ subq 2,$r11
+ blt _no_words
+ add.d $r13,$r12 ; checksum += r13
+
+ ;; checksum the rest of the words
+_wloop: subq 2,$r11
+ bge _wloop
+ addu.w [$r10+],$r12
+
+_no_words:
+ addq 2,$r11
+ ;; see if we have one odd byte more
+ bne _do_byte
+ nop
+ ret
+ move.d $r12,$r10
+
+_do_byte:
+ ;; copy and checksum the last byte
+ addu.b [$r10],$r12
+ ret
+ move.d $r12,$r10
+
+ .size csum_partial, .-csum_partial