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#if defined(LIBC_SCCS) && !defined(lint) 19 .asciz "@(#)strncpy.s 5.5 (Berkeley) 06/27/88" 20#endif /* LIBC_SCCS and not lint */ 21 22/* 23 * Copy string s2 over top of string s1. 24 * Truncate or null-pad to n bytes. 25 * 26 * char * 27 * strncpy(s1, s2, n) 28 * char *s1, *s2; 29 */ 30#include "DEFS.h" 31 32ENTRY(strncpy, R6) 33 movl 12(ap),r6 # r6 = n 34 bleq done # n <= 0 35 movl 4(ap),r3 # r3 = s1 36 movl 8(ap),r1 # r1 = s2 371: 38 movzwl $65535,r2 # r2 = bytes in first chunk 39 cmpl r6,r2 # r2 = min(bytes in chunk, n); 40 jgeq 2f 41 movl r6,r2 422: 43 subl2 r2,r6 # update n 44 locc $0,r2,(r1) # '\0' found? 45 jneq 3f 46 subl2 r2,r1 # back up pointer updated by locc 47 movc3 r2,(r1),(r3) # copy in next piece 48 tstl r6 # run out of space? 49 jneq 1b 50 jbr done 513: # copy up to '\0' logic 52 addl2 r0,r6 # r6 = number of null-pad bytes 53 subl2 r0,r2 # r2 = number of bytes to move 54 subl2 r2,r1 # back up pointer updated by locc 55 movc3 r2,(r1),(r3) # copy in last piece 564: # null-pad logic 57 movzwl $65535,r2 # r2 = bytes in first chunk 58 cmpl r6,r2 # r2 = min(bytes in chunk, n); 59 jgeq 5f 60 movl r6,r2 615: 62 subl2 r2,r6 # update n 63 movc5 $0,(r3),$0,r2,(r3)# pad with '\0's 64 tstl r6 # finished padding? 65 jneq 4b 66done: 67 movl 4(ap),r0 # return s1 68 ret 69