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