summaryrefslogtreecommitdiffstats
path: root/kernel/arch/cris/arch-v32/lib/checksumcopy.S
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/arch/cris/arch-v32/lib/checksumcopy.S')
-rw-r--r--kernel/arch/cris/arch-v32/lib/checksumcopy.S94
1 files changed, 94 insertions, 0 deletions
diff --git a/kernel/arch/cris/arch-v32/lib/checksumcopy.S b/kernel/arch/cris/arch-v32/lib/checksumcopy.S
new file mode 100644
index 000000000..54e209f18
--- /dev/null
+++ b/kernel/arch/cris/arch-v32/lib/checksumcopy.S
@@ -0,0 +1,94 @@
+/*
+ * A fast checksum+copy routine using movem
+ * Copyright (c) 1998-2007 Axis Communications AB
+ *
+ * Authors: Bjorn Wesen
+ *
+ * csum_partial_copy_nocheck(const char *src, char *dst,
+ * int len, unsigned int sum)
+ */
+
+ .globl csum_partial_copy_nocheck
+ .type csum_partial_copy_nocheck,@function
+csum_partial_copy_nocheck:
+
+ ;; r10 - src
+ ;; r11 - dst
+ ;; r12 - length
+ ;; r13 - checksum
+
+ ;; Optimized for large packets
+ subq 10*4, $r12
+ blt _word_loop
+ move.d $r12, $acr
+
+ subq 9*4,$sp
+ clearf c
+ movem $r8,[$sp]
+
+ ;; do a movem copy and checksum
+1: ;; A failing userspace access (the read) will have this as PC.
+_mloop: movem [$r10+],$r9 ; read 10 longwords
+ addoq -10*4, $acr, $acr ; loop counter in latency cycle
+ movem $r9,[$r11+] ; write 10 longwords
+
+ ;; perform dword checksumming on the 10 longwords
+ addc $r0,$r13
+ addc $r1,$r13
+ addc $r2,$r13
+ addc $r3,$r13
+ addc $r4,$r13
+ addc $r5,$r13
+ addc $r6,$r13
+ addc $r7,$r13
+ addc $r8,$r13
+ addc $r9,$r13
+
+ ;; test $acr, without trashing carry.
+ move.d $acr, $acr
+ bpl _mloop
+ ;; r12 <= acr is needed after mloop and in the exception handlers.
+ move.d $acr, $r12
+
+ ;; fold the last carry into r13
+ addc 0, $r13
+ movem [$sp+],$r8 ; restore regs
+
+_word_loop:
+ addq 10*4,$r12 ; compensate for last loop underflowing length
+
+ ;; fold 32-bit checksum into a 16-bit checksum, to avoid carries below
+ ;; r9 can be used as temporary.
+ move.d $r13,$r9
+ lsrq 16,$r9 ; r0 = checksum >> 16
+ and.d 0xffff,$r13 ; checksum = checksum & 0xffff
+
+ subq 2, $r12
+ blt _no_words
+ add.d $r9,$r13 ; checksum += r0
+
+ ;; copy and checksum the rest of the words
+2: ;; A failing userspace access for the read below will have this as PC.
+_wloop: move.w [$r10+],$r9
+ addu.w $r9,$r13
+ subq 2,$r12
+ bge _wloop
+ move.w $r9,[$r11+]
+
+_no_words:
+ addq 2,$r12
+ bne _do_byte
+ nop
+ ret
+ move.d $r13,$r10
+
+_do_byte:
+ ;; copy and checksum the last byte
+3: ;; A failing userspace access for the read below will have this as PC.
+ move.b [$r10],$r9
+ addu.b $r9,$r13
+ move.b $r9,[$r11]
+ ret
+ move.d $r13,$r10
+
+ .size csum_partial_copy_nocheck, . - csum_partial_copy_nocheck