patch-1.3.2 linux/include/asm-i386/checksum.h

• Lines: 121
• Date: Fri Jun 16 21:11:21 1995
• Orig file: v1.3.1/linux/include/asm-i386/checksum.h
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v1.3.1/linux/include/asm-i386/checksum.h linux/include/asm-i386/checksum.h
@@ -0,0 +1,120 @@
+#ifndef _I386_CHECKSUM_H
+#define _I386_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(unsigned char * buff, int len, unsigned int sum);
+
+/*
+ * the same as csum_partial, but copies from fs: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_copyffs( char *src, char *dst, int len, int sum);
+
+
+/*
+ *	This is a version of ip_compute_csum() optimized for IP headers,
+ *	which always checksum on 4 octet boundaries.
+ *
+ *	By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by
+ *	Arnt Gulbrandsen.
+ */
+static inline unsigned short ip_fast_csum(unsigned char * iph,
+					  unsigned int ihl) {
+	unsigned short int sum;
+
+	__asm__("
+	    movl (%%esi), %%eax
+	    andl $15, %%ecx
+	    subl $4, %%ecx
+	    jbe 2f
+	    addl 4(%%esi), %%eax
+	    adcl 8(%%esi), %%eax
+	    adcl 12(%%esi), %%eax
+1:	    adcl 16(%%esi), %%eax
+	    lea 4(%%esi), %%esi
+	    decl %%ecx
+	    jne	1b
+	    adcl $0, %%eax
+	    movl %%eax, %%ecx
+	    shrl $16, %%eax
+	    addw %%ecx, %%eax
+	    adcl $0, %%eax
+	    notl %%eax
+	    andl $65535, %%eax
+2:
+	    "
+	: "=a" (sum)
+	: "S" (iph), "c"(ihl)
+	: "ax", "cx", "si");
+	return(sum);
+}
+
+
+
+
+/*
+ * 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) {
+    __asm__("
+	addl %2, %0
+	adcl %3, %0
+	adcl %4, %0
+	adcl $0, %0
+	movl %0, %2
+	shrl $16, %2
+	addw %2, %0
+	adcl $0, %0
+	notl %0
+	andl $65535, %0
+	"
+	: "=r" (sum)
+	: "0" (daddr), "S"(saddr), "r"((ntohs(len)<<16)+proto*256), "r"(sum)
+	: "si" );
+	return((unsigned short)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) {
+    unsigned short int sum;
+
+    __asm__("
+	movl %%eax, %%ecx
+	shrl $16, %%ecx
+	addw %%cx, %%ax
+	adcl $0, %%eax
+	notl %%eax
+	andl $65535, %%eax
+	"
+	: "=a"(sum)
+	: "a" (csum_partial(buff, len, 0))
+	: "cx");
+	return(sum);
+}
+
+#endif