patch-2.4.0-test12 linux/arch/parisc/lib/checksum.c

• Lines: 131
• Date: Tue Dec 5 12:29:39 2000
• Orig file: v2.4.0-test11/linux/arch/parisc/lib/checksum.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.4.0-test11/linux/arch/parisc/lib/checksum.c linux/arch/parisc/lib/checksum.c
@@ -0,0 +1,130 @@
+/*
+ * 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.
+ *
+ * $Id: checksum.c,v 1.3 1997/12/01 17:57:34 ralf Exp $
+ */
+#include <net/checksum.h>
+#include <linux/types.h>
+#include <asm/byteorder.h>
+#include <asm/string.h>
+#include <asm/uaccess.h>
+
+static inline unsigned short from32to16(unsigned int x)
+{
+	/* 32 bits --> 16 bits + carry */
+	x = (x & 0xffff) + (x >> 16);
+	/* 16 bits + carry --> 16 bits including carry */
+	x = (x & 0xffff) + (x >> 16);
+	return (unsigned short)x;
+}
+
+static inline unsigned int do_csum(const unsigned char * buff, int len)
+{
+	int odd, count;
+	unsigned int result = 0;
+
+	if (len <= 0)
+		goto out;
+	odd = 1 & (unsigned long) buff;
+	if (odd) {
+		result = be16_to_cpu(*buff);
+		len--;
+		buff++;
+	}
+	count = len >> 1;		/* nr of 16-bit words.. */
+	if (count) {
+		if (2 & (unsigned long) buff) {
+			result += *(unsigned short *) buff;
+			count--;
+			len -= 2;
+			buff += 2;
+		}
+		count >>= 1;		/* nr of 32-bit words.. */
+		if (count) {
+			unsigned int carry = 0;
+			do {
+				unsigned int w = *(unsigned int *) buff;
+				count--;
+				buff += 4;
+				result += carry;
+				result += w;
+				carry = (w > result);
+			} while (count);
+			result += carry;
+			result = (result & 0xffff) + (result >> 16);
+		}
+		if (len & 2) {
+			result += *(unsigned short *) buff;
+			buff += 2;
+		}
+	}
+	if (len & 1)
+		result += le16_to_cpu(*buff);
+	result = from32to16(result);
+	if (odd)
+		result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
+out:
+	return result;
+}
+
+/*
+ * computes a partial checksum, e.g. for TCP/UDP fragments
+ */
+unsigned int csum_partial(const unsigned char *buff, int len, unsigned int sum)
+{
+	unsigned int result = do_csum(buff, len);
+
+	/* add in old sum, and carry.. */
+	result += sum;
+	if(sum > result)
+		result += 1;
+	return result;
+}
+
+/*
+ * copy while checksumming, otherwise like csum_partial
+ */
+unsigned int csum_partial_copy(const char *src, char *dst, 
+                               int len, unsigned 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;
+}
+
+/*
+ * Copy from userspace and compute checksum.  If we catch an exception
+ * then zero the rest of the buffer.
+ */
+unsigned int csum_partial_copy_from_user (const char *src, char *dst,
+                                          int len, unsigned int sum,
+                                          int *err_ptr)
+{
+	int missing;
+
+	missing = copy_from_user(dst, src, len);
+	if (missing) {
+		memset(dst + len - missing, 0, missing);
+		*err_ptr = -EFAULT;
+	}
+		
+	return csum_partial(dst, len, sum);
+}