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) 06/18/88"; 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 } 68