patch-2.3.99-pre8 linux/arch/s390/lib/checksum.c

• Lines: 57
• Date: Fri May 12 11:41:45 2000
• Orig file: v2.3.99-pre7/linux/arch/s390/lib/checksum.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.99-pre7/linux/arch/s390/lib/checksum.c linux/arch/s390/lib/checksum.c
@@ -0,0 +1,56 @@
+/*
+ *  arch/s390/lib/checksum.c
+ *    S390 fast network checksum routines
+ *
+ *  S390 version
+ *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
+ *    Author(s): Ulrich Hild        (first version),
+ *               Martin Schwidefsky (schwidefsky@de.ibm.com),
+ *               Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
+ *
+ * This file contains network checksum routines
+ */
+ 
+#include <linux/string.h>
+#include <linux/types.h>
+#include <asm/uaccess.h>
+#include <asm/byteorder.h>
+#include <asm/checksum.h>
+
+/*
+ * computes a partial checksum, e.g. for TCP/UDP fragments
+ */
+unsigned int
+csum_partial (const unsigned char *buff, int len, unsigned int sum)
+{
+	  /*
+	   * Experiments with ethernet and slip connections show that buff
+	   * is aligned on either a 2-byte or 4-byte boundary.
+	   */
+        __asm__ __volatile__ (
+                "    lr   2,%1\n"    /* address in gpr 2 */
+                "    lr   3,%2\n"    /* length in gpr 3 */
+                "0:  cksm %0,2\n"    /* do checksum on longs */
+                "    jo   0b\n"
+                : "+&d" (sum)
+                : "d" (buff), "d" (len)
+                : "cc", "2", "3" );
+        return sum;
+}
+
+/*
+ *	Fold a partial checksum without adding pseudo headers
+ */
+unsigned short csum_fold(unsigned int sum)
+{
+        __asm__ __volatile__ (
+                "    sr   3,3\n"   /* %0 = H*65536 + L */
+                "    lr   2,%0\n"  /* %0 = H L, R2/R3 = H L / 0 0 */
+                "    srdl 2,16\n"  /* %0 = H L, R2/R3 = 0 H / L 0 */
+                "    alr  2,3\n"   /* %0 = H L, R2/R3 = L H / L 0 */
+                "    alr  %0,2\n"  /* %0 = H+L+C L+H */
+                "    srl  %0,16\n" /* %0 = H+L+C */
+                : "+d" (sum) : : "cc", "2", "3");
+        return ((unsigned short) ~sum);
+}
+