From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Wed, 5 Aug 2015 17:04:01 -0300
Subject: Initial import

---
 arch/cris/arch-v32/lib/checksumcopy.S | 94 +++++++++++++++++++++++++++++++++++
 1 file changed, 94 insertions(+)
 create mode 100644 arch/cris/arch-v32/lib/checksumcopy.S

(limited to 'arch/cris/arch-v32/lib/checksumcopy.S')

diff --git a/arch/cris/arch-v32/lib/checksumcopy.S b/arch/cris/arch-v32/lib/checksumcopy.S
new file mode 100644
index 000000000..54e209f18
--- /dev/null
+++ b/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
-- 
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