patch-2.4.2 linux/include/asm-cris/checksum.h

• Lines: 120
• Date: Thu Feb 8 16:32:44 2001
• Orig file: v2.4.1/linux/include/asm-cris/checksum.h
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.4.1/linux/include/asm-cris/checksum.h linux/include/asm-cris/checksum.h
@@ -0,0 +1,119 @@
+/* $Id: checksum.h,v 1.3 2000/11/15 17:35:16 bjornw Exp $ */
+/* TODO: csum_tcpudp_magic could be speeded up, and csum_fold as well */
+
+#ifndef _CRIS_CHECKSUM_H
+#define _CRIS_CHECKSUM_H
+
+/*
+ * computes the checksum of a memory block at buff, length len,
+ * and adds in "sum" (32-bit)
+ *
+ * returns a 32-bit number suitable for feeding into itself
+ * or csum_tcpudp_magic
+ *
+ * this function must be called with even lengths, except
+ * for the last fragment, which may be odd
+ *
+ * it's best to have buff aligned on a 32-bit boundary
+ */
+unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum);
+
+/*
+ * the same as csum_partial, but copies from src while it
+ * checksums
+ *
+ * here even more important to align src and dst on a 32-bit (or even
+ * better 64-bit) boundary
+ */
+
+unsigned int csum_partial_copy_nocheck(const char *src, char *dst,
+				       int len, unsigned int sum);
+
+/*
+ *	Fold a partial checksum into a word
+ */
+
+static inline unsigned int csum_fold(unsigned int sum)
+{
+	/* the while loop is unnecessary really, it's always enough with two
+	   iterations */
+	
+	while(sum >> 16)
+		sum = (sum & 0xffff) + (sum >> 16); /* add in end-around carry */
+	
+	return ~sum;
+}
+
+/* Checksum some values used in TCP/UDP headers.
+ *
+ * The gain by doing this in asm is that C will not generate carry-additions
+ * for the 32-bit components of the checksum, so otherwise we would have had
+ * to split all of those into 16-bit components, then add.
+ */
+
+static inline unsigned int
+csum_tcpudp_nofold(unsigned long saddr, unsigned long daddr, unsigned short len,
+		   unsigned short proto, unsigned int sum)
+{
+	int res;
+	__asm__ ("add.d %2, %0\n\t"
+		 "ax\n\t"
+		 "add.d %3, %0\n\t"
+		 "ax\n\t"
+		 "add.d %4, %0\n\t"
+		 "ax\n\t"
+		 "addq 0, %0\n"
+	: "=r" (res)
+	: "0" (sum), "r" (daddr), "r" (saddr), "r" ((ntohs(len) << 16) + (proto << 8)));
+
+	return res;
+}	
+
+
+/* TODO we need to write this properly to handle userland VM exceptions!! */
+
+#define csum_partial_copy_from_user(a,b,c,d,errptr) csum_partial_copy_nocheck(a,b,c,d)
+
+#if 0
+unsigned int csum_partial_copy_from_user(const char *src, char *dst,
+					int len, unsigned int sum);
+#endif
+
+
+
+/*
+ *	This is a version of ip_compute_csum() optimized for IP headers,
+ *	which always checksum on 4 octet boundaries.
+ *
+ */
+
+static inline unsigned short ip_fast_csum(unsigned char * iph,
+					  unsigned int ihl)
+{
+	return csum_fold(csum_partial(iph, ihl * 4, 0));
+}
+ 
+/*
+ * computes the checksum of the TCP/UDP pseudo-header
+ * returns a 16-bit checksum, already complemented
+ */
+
+static inline unsigned short int csum_tcpudp_magic(unsigned long saddr,
+						   unsigned long daddr,
+						   unsigned short len,
+						   unsigned short proto,
+						   unsigned int sum)
+{
+	return csum_fold(csum_tcpudp_nofold(saddr,daddr,len,proto,sum));
+}
+
+/*
+ * this routine is used for miscellaneous IP-like checksums, mainly
+ * in icmp.c
+ */
+
+static inline unsigned short ip_compute_csum(unsigned char * buff, int len) {
+	return csum_fold (csum_partial(buff, len, 0));
+}
+
+#endif