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Annotation of 43BSDTahoe/etc/timed/cksum.vax.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Copyright (c) 1983 Regents of the University of California.
                      3:  * All rights reserved.
                      4:  *
                      5:  * Redistribution and use in source and binary forms are permitted
                      6:  * provided that the above copyright notice and this paragraph are
                      7:  * duplicated in all such forms and that any documentation,
                      8:  * advertising materials, and other materials related to such
                      9:  * distribution and use acknowledge that the software was developed
                     10:  * by the University of California, Berkeley.  The name of the
                     11:  * University may not be used to endorse or promote products derived
                     12:  * from this software without specific prior written permission.
                     13:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
                     14:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
                     15:  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
                     16:  */
                     17: 
                     18: #ifndef lint
                     19: static char sccsid[] = "@(#)cksum.vax.c        1.4 (Berkeley) 6/18/88";
                     20: #endif /* not lint */
                     21: 
                     22: #include <sys/types.h>
                     23: 
                     24: #define ADD    asm("adwc (r9)+,r8;");
                     25: 
                     26: /* computes the checksum for ip packets for the VAX */
                     27: 
                     28: in_cksum(addr, len)
                     29: u_short *addr;
                     30: int len;
                     31: {
                     32:        register int nleft = len;       /* on vax, (user mode), r11 */
                     33: #ifndef lint
                     34:        register int xxx;               /* on vax, (user mode), r10 */
                     35: #endif not lint
                     36:        register u_short *w = addr;     /* on vax, known to be r9 */
                     37:        register int sum = 0;           /* on vax, known to be r8 */
                     38: 
                     39:        if (((int)w&0x2) && nleft >= 2) {
                     40:                sum += *w++;
                     41:                nleft -= 2;
                     42:        }
                     43:        while ((nleft -= 32) >= 0) {
                     44:                asm("clrl r0");         /* clears carry */
                     45:                ADD; ADD; ADD; ADD; ADD; ADD; ADD; ADD;
                     46:                asm("adwc $0,r8");
                     47:        }
                     48:        nleft += 32;
                     49:        while ((nleft -= 8) >= 0) {
                     50:                asm("clrl r0");
                     51:                ADD; ADD;
                     52:                asm("adwc $0,r8");
                     53:        }
                     54:        nleft += 8;
                     55:        { asm("ashl $-16,r8,r0; addw2 r0,r8");
                     56:          asm("adwc $0,r8; movzwl r8,r8"); }
                     57:        while ((nleft -= 2) >= 0) {
                     58:                asm("movzwl (r9)+,r0; addl2 r0,r8");
                     59:        }
                     60:        if (nleft == -1) {
                     61:                sum += *(u_char *)w;
                     62:        }
                     63: 
                     64:        { asm("ashl $-16,r8,r0; addw2 r0,r8; adwc $0,r8");
                     65:          asm("mcoml r8,r8; movzwl r8,r8"); }
                     66:        return (sum);
                     67: }

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