aboutsummaryrefslogtreecommitdiff
path: root/arch/metag/lib/ip_fast_csum.S
diff options
context:
space:
mode:
Diffstat (limited to 'arch/metag/lib/ip_fast_csum.S')
-rw-r--r--arch/metag/lib/ip_fast_csum.S32
1 files changed, 32 insertions, 0 deletions
diff --git a/arch/metag/lib/ip_fast_csum.S b/arch/metag/lib/ip_fast_csum.S
new file mode 100644
index 00000000000..533b1e73dea
--- /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