patch-2.3.43 linux/arch/ia64/lib/csum_partial_copy.c

• Lines: 166
• Date: Sun Feb 6 18:42:40 2000
• Orig file: v2.3.42/linux/arch/ia64/lib/csum_partial_copy.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.42/linux/arch/ia64/lib/csum_partial_copy.c linux/arch/ia64/lib/csum_partial_copy.c
@@ -0,0 +1,165 @@
+/*
+ * Network Checksum & Copy routine
+ * 
+ * Copyright (C) 1999 Hewlett-Packard Co
+ * Copyright (C) 1999 Stephane Eranian <eranian@hpl.hp.com>
+ *
+ * Most of the code has been imported from Linux/Alpha
+ */
+
+#include <linux/types.h>
+#include <linux/string.h>
+
+#include <asm/uaccess.h>
+
+/*
+ * XXX Fixme: those 2 inlines are meant for debugging and will go away
+ */
+static inline unsigned
+short from64to16(unsigned long x)
+{
+	/* add up 32-bit words for 33 bits */
+	x = (x & 0xffffffff) + (x >> 32);
+	/* add up 16-bit and 17-bit words for 17+c bits */
+	x = (x & 0xffff) + (x >> 16);
+	/* add up 16-bit and 2-bit for 16+c bit */
+	x = (x & 0xffff) + (x >> 16);
+	/* add up carry.. */
+	x = (x & 0xffff) + (x >> 16);
+	return x;
+}
+
+static inline
+unsigned long do_csum_c(const unsigned char * buff, int len, unsigned int psum)
+{
+	int odd, count;
+	unsigned long result = (unsigned long)psum;
+
+	if (len <= 0)
+		goto out;
+	odd = 1 & (unsigned long) buff;
+	if (odd) {
+		result = *buff << 8;
+		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) {
+			if (4 & (unsigned long) buff) {
+				result += *(unsigned int *) buff;
+				count--;
+				len -= 4;
+				buff += 4;
+			}
+			count >>= 1;	/* nr of 64-bit words.. */
+			if (count) {
+				unsigned long carry = 0;
+				do {
+					unsigned long w = *(unsigned long *) buff;
+					count--;
+					buff += 8;
+					result += carry;
+					result += w;
+					carry = (w > result);
+				} while (count);
+				result += carry;
+				result = (result & 0xffffffff) + (result >> 32);
+			}
+			if (len & 4) {
+				result += *(unsigned int *) buff;
+				buff += 4;
+			}
+		}
+		if (len & 2) {
+			result += *(unsigned short *) buff;
+			buff += 2;
+		}
+	}
+	if (len & 1)
+		result += *buff;
+
+	result = from64to16(result);
+
+	if (odd)
+		result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
+
+out:
+	return result;
+}
+
+/*
+ * XXX Fixme
+ *
+ * This is very ugly but temporary. THIS NEEDS SERIOUS ENHANCEMENTS.
+ * But it's very tricky to get right even in C.
+ */
+extern unsigned long do_csum(const unsigned char *, int);
+
+static unsigned int
+do_csum_partial_copy_from_user (const char *src, char *dst, int len,
+				unsigned int psum, int *errp)
+{
+	const unsigned char *psrc = src;
+	unsigned long result;
+	int cplen = len;
+	int r = 0;
+
+	/* XXX Fixme
+	 * for now we separate the copy from checksum for obvious 
+	 * alignment difficulties. Look at the Alpha code and you'll be
+	 * scared.
+	 */
+
+	while ( cplen-- ) r |=__get_user(*dst++,psrc++);
+
+	if ( r && errp ) *errp = r;
+
+	result = do_csum(src, len);
+
+	/* add in old sum, and carry.. */
+	result += psum;
+	/* 32+c bits -> 32 bits */
+	result = (result & 0xffffffff) + (result >> 32);
+	return result;
+}
+
+unsigned int
+csum_partial_copy_from_user(const char *src, char *dst, int len,
+			    unsigned int sum, int *errp)
+{
+	if (!access_ok(src, len, VERIFY_READ)) {
+		*errp = -EFAULT;
+		memset(dst, 0, len);
+		return sum;
+	}
+
+	return do_csum_partial_copy_from_user(src, dst, len, sum, errp);
+}
+
+unsigned int
+csum_partial_copy_nocheck(const char *src, char *dst, int len, unsigned int sum)
+{
+	return do_csum_partial_copy_from_user(src, dst, len, sum, NULL);
+}
+
+unsigned int
+csum_partial_copy (const char *src, char *dst, int len, unsigned int sum)
+{
+	unsigned int ret;
+	int error = 0;
+
+	ret = do_csum_partial_copy_from_user(src, dst, len, sum, &error);
+	if (error)
+		printk("csum_partial_copy_old(): tell mingo to convert me!\n");
+
+	return ret;
+}
+