Module Name: src
Committed By: matt
Date: Tue Dec 18 13:41:42 UTC 2012
Added Files:
src/sys/arch/arm/arm: cpu_in_cksum_v4hdr.S
Log Message:
Add a routine to compute the IP checksum of a 20-byte IP header.
To generate a diff of this commit:
cvs rdiff -u -r0 -r1.1 src/sys/arch/arm/arm/cpu_in_cksum_v4hdr.S
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Added files:
Index: src/sys/arch/arm/arm/cpu_in_cksum_v4hdr.S
diff -u /dev/null src/sys/arch/arm/arm/cpu_in_cksum_v4hdr.S:1.1
--- /dev/null Tue Dec 18 13:41:42 2012
+++ src/sys/arch/arm/arm/cpu_in_cksum_v4hdr.S Tue Dec 18 13:41:42 2012
@@ -0,0 +1,70 @@
+/*-
+ * Copyright (c) 2012 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Matt Thomas of 3am Software Foundry.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <machine/asm.h>
+
+RCSID("$NetBSD: cpu_in_cksum_v4hdr.S,v 1.1 2012/12/18 13:41:42 matt Exp $")
+
+ENTRY(cpu_in_cksum_v4hdr)
+ ldr ip, [r0] /* load 1st word */
+ ldr r3, [r0, #4] /* load 2nd word */
+ adds r3, r3, ip /* add 1st to 2nd */
+ ldr r2, [r0, #8] /* load 3rd word */
+ adcs r2, r2, r3 /* add sum to 3rd */
+ ldr r1, [r0, #12] /* load 4th word */
+ adcs r1, r1, r2 /* add sum to 4th */
+ ldr r0, [r0, #16] /* load 5th word */
+ adcs r0, r0, r1 /* add sum to 5th */
+ /*
+ * We now have a 33-bit (r0 + carry) sum which needs to resolved to a
+ * 16-bit sum.
+ */
+ mov r1, r0, lsr #16 /* get upper halfword */
+#ifdef _ARM_ARCH_6
+ uxth r0, r0 /* clear upper halfword (16bit carry) */
+#else
+ bic r0, r0, #0x00ff0000 /* clear upper halfword (16bit carry) */
+ bic r0, r0, #0xff000000 /* clear upper halfword */
+#endif
+ adc r0, r0, r1 /* add halfwords with leftover carry */
+ /*
+ * At this point, we have a sum with a max of 0x1fffe.
+ * If we have a 17-bit value (>= 0x10000) then subtract 0xffff.
+ */
+ cmp r0, #0x10000 /* test 16-bit carry */
+#ifdef _ARM_ARCH_7
+ movw r1, #0xffff /* load 0xffff */
+#else
+ mov r1, #0x10000 /* load 0x10000 */
+ sub r1, r1, #1 /* subtract 1 to get 0xffff */
+#endif
+ subge r0, r0, r1 /* subtract 0xffff */
+ eor r0, r0, r1 /* complement lower halfword */
+ RET
+END(cpu_in_cksum_v4hdr)
