projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 586c39b1 DF |
1 | /* |
| 2 | * Copyright (c) 1983 Regents of the University of California. | |
| 493b70ca KB |
3 | * All rights reserved. |
| 4 | * | |
| 019bea33 | 5 | * %sccs.include.redist.c% |
| 586c39b1 DF |
6 | */ |
| 7 | ||
| f4f66d2c | 8 | #if defined(LIBC_SCCS) && !defined(lint) |
| 019bea33 | 9 | .asciz "@(#)strncpy.s 5.6 (Berkeley) %G%" |
| f4f66d2c | 10 | #endif /* LIBC_SCCS and not lint */ |
| d5803ce3 SL |
11 | |
| 12 | /* | |
| 13 | * Copy string s2 over top of string s1. | |
| 14 | * Truncate or null-pad to n bytes. | |
| 15 | * | |
| 16 | * char * | |
| 17 | * strncpy(s1, s2, n) | |
| 18 | * char *s1, *s2; | |
| 19 | */ | |
| dadab5a2 | 20 | #include "DEFS.h" |
| d5803ce3 | 21 | |
| dadab5a2 | 22 | ENTRY(strncpy, R6) |
| d5803ce3 SL |
23 | movl 12(ap),r6 # r6 = n |
| 24 | bleq done # n <= 0 | |
| 25 | movl 4(ap),r3 # r3 = s1 | |
| 26 | movl 8(ap),r1 # r1 = s2 | |
| 27 | 1: | |
| 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 | |
| 32 | 2: | |
| 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 | jbr done | |
| 41 | 3: # copy up to '\0' logic | |
| 42 | addl2 r0,r6 # r6 = number of null-pad bytes | |
| 43 | subl2 r0,r2 # r2 = number of bytes to move | |
| 44 | subl2 r2,r1 # back up pointer updated by locc | |
| 45 | movc3 r2,(r1),(r3) # copy in last piece | |
| 46 | 4: # null-pad logic | |
| 47 | movzwl $65535,r2 # r2 = bytes in first chunk | |
| 48 | cmpl r6,r2 # r2 = min(bytes in chunk, n); | |
| 49 | jgeq 5f | |
| 50 | movl r6,r2 | |
| 51 | 5: | |
| 52 | subl2 r2,r6 # update n | |
| 53 | movc5 $0,(r3),$0,r2,(r3)# pad with '\0's | |
| 54 | tstl r6 # finished padding? | |
| 55 | jneq 4b | |
| 56 | done: | |
| 57 | movl 4(ap),r0 # return s1 | |
| 58 | ret |