1 /* 2 * Copyright (c) 1983 Regents of the University of California. 3 * All rights reserved. The Berkeley software License Agreement 4 * specifies the terms and conditions for redistribution. 5 */ 6 7 #ifndef lint 8 static char sccsid[] = "@(#)cksum.vax.c 1.1 (Berkeley) 06/22/85"; 9 #endif not lint 10 11 #include "../globals.h" 12 #include <protocols/timed.h> 13 14 #define ADD asm("adwc (r9)+,r8;"); 15 16 /* computes the checksum for ip packets for the VAX */ 17 18 in_cksum(addr, len) 19 u_short *addr; 20 int len; 21 { 22 register int nleft = len; /* on vax, (user mode), r11 */ 23 #ifndef lint 24 register int xxx; /* on vax, (user mode), r10 */ 25 #endif not lint 26 register u_short *w = addr; /* on vax, known to be r9 */ 27 register int sum = 0; /* on vax, known to be r8 */ 28 29 if (((int)w&0x2) && nleft >= 2) { 30 sum += *w++; 31 nleft -= 2; 32 } 33 while ((nleft -= 32) >= 0) { 34 asm("clrl r0"); /* clears carry */ 35 ADD; ADD; ADD; ADD; ADD; ADD; ADD; ADD; 36 asm("adwc $0,r8"); 37 } 38 nleft += 32; 39 while ((nleft -= 8) >= 0) { 40 asm("clrl r0"); 41 ADD; ADD; 42 asm("adwc $0,r8"); 43 } 44 nleft += 8; 45 { asm("ashl $-16,r8,r0; addw2 r0,r8"); 46 asm("adwc $0,r8; movzwl r8,r8"); } 47 while ((nleft -= 2) >= 0) { 48 asm("movzwl (r9)+,r0; addl2 r0,r8"); 49 } 50 if (nleft == -1) { 51 sum += *(u_char *)w; 52 } 53 54 { asm("ashl $-16,r8,r0; addw2 r0,r8; adwc $0,r8"); 55 asm("mcoml r8,r8; movzwl r8,r8"); } 56 return (sum); 57 } 58