patch-1.3.48 linux/arch/mips/lib/checksum.c

• Lines: 149
• Date: Wed Dec 13 12:39:44 1995
• Orig file: v1.3.47/linux/arch/mips/lib/checksum.c
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v1.3.47/linux/arch/mips/lib/checksum.c linux/arch/mips/lib/checksum.c
@@ -0,0 +1,148 @@
+/*
+ * INET		An implementation of the TCP/IP protocol suite for the LINUX
+ *		operating system.  INET is implemented using the  BSD Socket
+ *		interface as the means of communication with the user level.
+ *
+ *		MIPS specific IP/TCP/UDP checksumming routines
+ *
+ * Authors:	Ralf Baechle, <ralf@waldorf-gmbh.de>
+ *		Lots of code moved from tcp.c and ip.c; see those files
+ *		for more names.
+ *
+ *		This program is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU General Public License
+ *		as published by the Free Software Foundation; either version
+ *		2 of the License, or (at your option) any later version.
+ */
+#include <net/checksum.h>
+#include <asm/string.h>
+
+/*
+ * computes a partial checksum, e.g. for TCP/UDP fragments
+ */
+
+unsigned int csum_partial(const unsigned char *buff, int len, unsigned int sum)
+{
+	unsigned long	scratch1;
+	unsigned long	scratch2;
+
+	/*
+	 * The GCC generated code for handling carry bits makes
+	 * it strongly desireable to do this in assembler!
+	 */
+    __asm__("
+	.set	noreorder
+	.set	noat
+	andi	$1,%5,2		# Check alignment
+	beqz	$1,2f		# Branch if ok
+	subu	$1,%4,2		# delay slot, Alignment uses up two bytes
+	bgez	$1,1f		# Jump if we had at least two bytes
+	move	%4,$1		# delay slot
+	j	4f
+	addiu	%4,2		# delay slot; len was < 2.  Deal with it
+
+1:	lw	%2,(%5)
+	addiu	%4,2
+	addu	%0,%2
+	sltu	$1,%0,%2
+	addu	%0,$1
+
+2:	move	%1,%4
+	srl	%1,%1,5
+	beqz	%1,2f
+	sll	%1,%1,5		# delay slot
+
+	addu	%1,%5
+1:	lw	%2,0(%5)
+	addu	%5,32
+	addu	%0,%2
+	sltu	$1,%0,%2
+
+	lw	%2,-28(%5)
+	addu	%0,$1
+	addu	%0,%2
+	sltu	$1,%0,%2
+
+	lw	%2,-24(%5)
+	addu	%0,$1
+	addu	%0,%2
+	sltu	$1,%0,%2
+
+	lw	%2,-20(%5)
+	addu	%0,$1
+	addu	%0,%2
+	sltu	$1,%0,%2
+
+	lw	%2,-16(%5)
+	addu	%0,$1
+	addu	%0,%2
+	sltu	$1,%0,%2
+
+	lw	%2,-12(%5)
+	addu	%0,$1
+	addu	%0,%2
+	sltu	$1,%0,%2
+
+	lw	%2,-8(%5)
+	addu	%0,$1
+	addu	%0,%2
+	sltu	$1,%0,%2
+
+	lw	%2,-4(%5)
+	addu	%0,$1
+	addu	%0,%2
+	sltu	$1,%0,%2
+
+	bne	%5,%1,1b
+	addu	%0,$1		# delay slot
+
+2:	andi	%1,%4,0x1c
+	srl	%1,%1,2
+	beqz	%1,4f
+	addu	%1,%5		# delay slot
+3:	lw	%2,0(%5)
+	addu	%5,4
+	addu	%0,%2
+	sltu	$1,%0,%2
+	bne	%5,%1,3b
+	addu	%0,$1		# delay slot
+
+4:	andi	$1,%3,2
+	beqz	$1,5f
+	move	%2,$0		# delay slot
+	lhu	%2,(%5)
+	addiu	%5,2
+
+5:	andi	$1,%3,1
+	beqz	$1,6f
+	sll	%1,16		# delay slot
+	lbu	%1,(%5)
+	nop			# NOP ALERT (spit, gasp)
+6:	or	%2,%1
+	addu	%0,%2
+	sltu	$1,%0,%2
+	addu	%0,$1
+7:	.set	at
+	.set	reorder"
+	: "=r"(sum), "=r" (scratch1), "=r" (scratch2)
+	: "0"(sum), "r"(len), "r"(buff)
+	: "$1");
+
+	return sum;
+}
+
+/*
+ * copy from fs while checksumming, otherwise like csum_partial
+ */
+unsigned int csum_partial_copy(const char *src, char *dst, 
+				  int len, int sum)
+{
+	/*
+	 * It's 2:30 am and I don't feel like doing it real ...
+	 * This is lots slower than the real thing (tm)
+	 */
+	sum = csum_partial(src, len, sum);
+	memcpy(dst, src, len);
+
+	return sum;
+}