faster cksum

SCCS-vsn: sys/vax/vax/in_cksum.c 1.4

diff --git a/usr/src/sys/vax/vax/in_cksum.c b/usr/src/sys/vax/vax/in_cksum.c
index 9e53968..4b41339 100644 (file)
--- a/usr/src/sys/vax/vax/in_cksum.c
+++ b/usr/src/sys/vax/vax/in_cksum.c
@@ -1,4 +1,4 @@
-/* in_cksum.c 1.3 81/10/18 */
+/* in_cksum.c 1.4 81/10/20 */

 
 #include <sys/types.h>
 #include "../bbnnet/net.h"
 
 #include <sys/types.h>
 #include "../bbnnet/net.h"


@@ -19,8 +19,9 @@ cksum(m, len)
        register struct mbuf *m;
        register int len;
 {
        register struct mbuf *m;
        register int len;
 {

-       register u_short *w;            /* known to be r9 */
+       register long *l;               /* known to be r9 */

        register int sum = 0;           /* known to be r8 */
        register int sum = 0;           /* known to be r8 */

+       register u_short *w;            /* known to be r7 */

        register int mlen = 0;
 COUNT(CKSUM);
 
        register int mlen = 0;
 COUNT(CKSUM);
 


@@ -37,18 +38,25 @@ COUNT(CKSUM);
                if (len < mlen)
                        mlen = len;
                len -= mlen;
                if (len < mlen)
                        mlen = len;
                len -= mlen;

+               l = (long *)w;

                while ((mlen -= 32) >= 0) {
                while ((mlen -= 32) >= 0) {

-#define ADD            asm("movzwl (r9)+,r0; addl2 r0,r8");
-                       ADD; ADD; ADD; ADD; ADD; ADD; ADD; ADD;
+                       asm("clrl r0");         /* clears carry */
+#undef ADD
+#define ADD            asm("adwc (r9)+,r8;");

                        ADD; ADD; ADD; ADD; ADD; ADD; ADD; ADD;
                        ADD; ADD; ADD; ADD; ADD; ADD; ADD; ADD;

+                       asm("adwc $0,r8");

                }
                mlen += 32;
                while ((mlen -= 8) >= 0) {
                }
                mlen += 32;
                while ((mlen -= 8) >= 0) {

-                       ADD; ADD; ADD; ADD;
+                       asm("clrl r0");
+                       ADD; ADD;
+                       asm("adwc $0,r8");

                }
                mlen += 8;
                }
                mlen += 8;

+               sum = ((sum >> 16) & 0xffff) + (sum & 0xffff);
+               w = (u_short *)l;

                while ((mlen -= 2) >= 0) {
                while ((mlen -= 2) >= 0) {

-                       ADD;
+                       asm("movzwl (r7)+,r0; addl2 r0,r8");

                }
                if (mlen == -1)
                        sum += *(u_char *)w;
                }
                if (mlen == -1)
                        sum += *(u_char *)w;


@@ -67,11 +75,3 @@ COUNT(CKSUM);
 done:
        return(~(sum + (sum >> 16)) & 0xffff);
 }
 done:
        return(~(sum + (sum >> 16)) & 0xffff);
 }

-
-/*
- * These routines are implemented as inline expansions
- * and are mentioned here for reference only
- *
- *     htons and ntohs         do byte reverse of a 16 bit integer
- *     htonl and ntohl         do byte reverse of a 32 bit integer
- */