1 files changed, 126 insertions, 0 deletions
diff --git a/kernel/arch/cris/arch-v10/lib/checksumcopy.S b/kernel/arch/cris/arch-v10/lib/checksumcopy.S
new file mode 100644
index 000000000..540db8a5f
--- /dev/null
+++ b/kernel/arch/cris/arch-v10/lib/checksumcopy.S
@@ -0,0 +1,126 @@
+/*
+ * A fast checksum+copy routine using movem
+ * Copyright (c) 1998, 2001 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
+csum_partial_copy_nocheck:	
+	
+	;; r10 - src
+	;; r11 - dst
+	;; r12 - length
+	;; r13 - checksum
+
+	;; check for breakeven length between movem and normal word looping versions
+	;; we also do _NOT_ want to compute a checksum over more than the 
+	;; actual length when length < 40
+	
+	cmpu.w	80, $r12
+	blo	_word_loop
+	nop
+
+	;; need to save the registers we use below in the movem loop
+	;; this overhead is why we have a check above for breakeven length
+	;; only r0 - r8 have to be saved, the other ones are clobber-able
+	;; according to the ABI
+	
+	subq	9*4, $sp
+	movem	$r8, [$sp]
+	
+	;; do a movem copy and checksum
+
+	subq	10*4, $r12	; update length for the first loop
+	
+_mloop:	movem	[$r10+],$r9	; read 10 longwords
+1:	;; A failing userspace access will have this as PC.
+	movem	$r9,[$r11+]	; write 10 longwords
+
+	;; perform dword checksumming on the 10 longwords
+	
+	add.d	$r0,$r13
+	ax
+	add.d	$r1,$r13
+	ax
+	add.d	$r2,$r13
+	ax
+	add.d	$r3,$r13
+	ax
+	add.d	$r4,$r13
+	ax
+	add.d	$r5,$r13
+	ax
+	add.d	$r6,$r13
+	ax
+	add.d	$r7,$r13
+	ax
+	add.d	$r8,$r13
+	ax
+	add.d	$r9,$r13
+
+	;; fold the carry into the checksum, to avoid having to loop the carry
+	;; back into the top
+	
+	ax
+	addq	0,$r13
+
+	subq	10*4,$r12
+	bge	_mloop
+	nop
+
+	addq	10*4,$r12	; compensate for last loop underflowing length
+
+	movem	[$sp+],$r8	; restore regs
+
+_word_loop:
+	;; only fold if there is anything to fold.
+
+	cmpq	0,$r13
+	beq	_no_fold
+
+	;; 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
+	add.d	$r9,$r13	; checksum += r0
+	
+_no_fold:
+	cmpq	2,$r12
+	blt	_no_words
+	nop
+	
+	;; copy and checksum the rest of the words
+	
+	subq	2,$r12
+	
+_wloop:	move.w	[$r10+],$r9
+2:	;; A failing userspace access will have this as PC.
+	addu.w	$r9,$r13
+	subq	2,$r12
+	bge	_wloop
+	move.w	$r9,[$r11+]
+	
+	addq	2,$r12
+		
+_no_words:
+	;; see if we have one odd byte more
+	cmpq	1,$r12
+	beq	_do_byte
+	nop
+	ret
+	move.d	$r13, $r10
+
+_do_byte:	
+	;; copy and checksum the last byte
+	move.b	[$r10],$r9
+3:	;; A failing userspace access will have this as PC.
+	addu.b	$r9,$r13
+	move.b	$r9,[$r11]
+	ret
+	move.d	$r13, $r10