1/* strncat.s 4.1 84/11/01 */ 2 3/* 4 * Concatenate string s2 on the end of s1 5 * and return the base of s1. The parameter 6 * n is the maximum length of string s2 to 7 * concatenate. 8 * 9 * char * 10 * strncat(s1, s2, n) 11 * char *s1, *s2; 12 * int n; 13 */ 14 .globl _strncat 15 16_strncat: 17 .word 0x40 18 movl 12(ap),r6 # r6 = n 19 bleq done # n <= 0 20 movl 4(ap),r3 # r3 = s1 21 movl r3,r1 220: 23 locc $0,$65535,(r1) 24 beql 0b 25 movl r1,r3 # r3 = index(s1, '\0'); 26 movl 8(ap),r1 # r1 = s2 271: 28 movzwl $65535,r2 # r2 = bytes in first chunk 29 cmpl r6,r2 # r2 = min(bytes in chunk, n); 30 jgeq 2f 31 movl r6,r2 322: 33 subl2 r2,r6 # update n 34 locc $0,r2,(r1) # '\0' found? 35 jneq 3f 36 subl2 r2,r1 # back up pointer updated by locc 37 movc3 r2,(r1),(r3) # copy in next piece 38 tstl r6 # run out of space? 39 jneq 1b 40 clrb (r3) # force '\0' termination 41 jbr done 423: 43 subl2 r0,r2 # r2 = number of bytes to move 44 subl2 r2,r1 # back up pointer updated by locc 45 incl r2 # copy '\0' as well 46 movc3 r2,(r1),(r3) # copy in last piece 47done: 48 movl 4(ap),r0 # return s1 49 ret 50