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/metag/lib/ip_fast_csum.S | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 arch/metag/lib/ip_fast_csum.S

(limited to 'arch/metag/lib/ip_fast_csum.S')

diff --git a/arch/metag/lib/ip_fast_csum.S b/arch/metag/lib/ip_fast_csum.S
new file mode 100644
index 000000000..533b1e73d
--- /dev/null
+++ b/arch/metag/lib/ip_fast_csum.S
@@ -0,0 +1,32 @@
+
+	.text
+/*
+ * This is a version of ip_compute_csum() optimized for IP headers,
+ * which always checksum on 4 octet boundaries.
+ *
+ * extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl);
+ *
+ */
+	.global _ip_fast_csum
+	.type   _ip_fast_csum,function
+_ip_fast_csum:
+	!! TXRPT needs loops - 1
+	SUBS	TXRPT,D0Ar2,#1
+	MOV	D0Re0,#0
+	BLO	$Lfast_csum_exit
+$Lfast_csum_loop:
+	GETD	D1Ar3,[D1Ar1++]
+	ADDS	D0Re0,D0Re0,D1Ar3
+	ADDCS   D0Re0,D0Re0,#1
+	BR	$Lfast_csum_loop
+	LSR	D0Ar4,D0Re0,#16
+	AND	D0Re0,D0Re0,#0xffff
+	AND	D0Ar4,D0Ar4,#0xffff
+	ADD	D0Re0,D0Re0,D0Ar4
+	LSR	D0Ar4,D0Re0,#16
+	ADD	D0Re0,D0Re0,D0Ar4
+	XOR	D0Re0,D0Re0,#-1
+	AND	D0Re0,D0Re0,#0xffff
+$Lfast_csum_exit:
+	MOV	PC,D1RtP
+	.size _ip_fast_csum,.-_ip_fast_csum
-- 
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