projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 67093e19 KM |
1 | /* |
| 2 | * Copyright (c) 1985 Regents of the University of California. | |
| 2c817985 KB |
3 | * All rights reserved. |
| 4 | * | |
| 019bea33 | 5 | * %sccs.include.redist.c% |
| 67093e19 KM |
6 | */ |
| 7 | ||
| 4afb9d15 | 8 | #if defined(LIBC_SCCS) && !defined(lint) |
| 019bea33 | 9 | .asciz "@(#)fgets.s 5.6 (Berkeley) %G%" |
| 4afb9d15 | 10 | #endif /* LIBC_SCCS and not lint */ |
| 67093e19 KM |
11 | |
| 12 | /* | |
| 13 | * char *fgets(s, n, iptr); | |
| 14 | * char *s; | |
| 15 | * int n; | |
| 16 | * FILE *iptr; | |
| 17 | * | |
| 18 | * arguments: a target string, a length, and a file pointer. | |
| 19 | * side effects: reads up to and including a newline, or up to n-1 bytes, | |
| 20 | * whichever is less, from the file indicated by iptr into the target | |
| 21 | * string and null terminates. | |
| 22 | * result: the target string if successful, 0 otherwise. | |
| 23 | */ | |
| 24 | ||
| 25 | #include "DEFS.h" | |
| 26 | ||
| 27 | #define NL 0xa | |
| 28 | ||
| 29 | ENTRY(fgets, R11|R10|R9) | |
| 30 | ||
| 31 | #define OLD_S 4(ap) | |
| 32 | #define S r11 | |
| 33 | movl OLD_S,S | |
| 34 | ||
| 35 | #define N 8(ap) | |
| 36 | ||
| 37 | #define IPTR r10 | |
| 38 | #define _CNT | |
| 39 | #define _PTR 4 | |
| 40 | #define _BASE 8 | |
| 41 | movl 12(ap),IPTR | |
| 42 | ||
| 43 | #define COUNT r9 | |
| 44 | ||
| 45 | /* | |
| 46 | * Sanity check -- is the buffer big enough? | |
| 47 | */ | |
| 48 | cmpl N,$1 | |
| 49 | jleq Lerror | |
| 50 | ||
| 51 | subl3 $1,N,COUNT /* We scan at most COUNT chars */ | |
| 52 | ||
| 53 | /* | |
| 54 | * If no characters, call _filbuf() to get some. | |
| 55 | */ | |
| 56 | tstl _CNT(IPTR) | |
| 57 | jgtr Lscan | |
| 58 | ||
| 59 | Lloop: | |
| 60 | pushl IPTR | |
| 61 | calls $1,__filbuf | |
| 62 | tstl r0 | |
| 63 | jlss Leof | |
| 64 | movb r0,(S)+ /* Save the returned character */ | |
| 98f6d346 KM |
65 | decl N |
| 66 | decl COUNT | |
| 67 | jleq 1f | |
| 67093e19 | 68 | cmpb r0,$NL /* If it was a newline, we're done */ |
| 98f6d346 KM |
69 | jneq 2f |
| 70 | 1: | |
| 67093e19 KM |
71 | clrb (S) |
| 72 | jbr Lret | |
| 98f6d346 | 73 | 2: |
| 67093e19 KM |
74 | tstl _BASE(IPTR) /* Is the input buffered? */ |
| 75 | jeql Lloop /* If not, loop inefficiently */ | |
| 76 | ||
| 77 | /* | |
| 78 | * Look for a newline in the buffer. | |
| 79 | */ | |
| 80 | Lscan: | |
| 81 | cmpl _CNT(IPTR),COUNT /* Is buffer bigger than N-1? */ | |
| 82 | jgeq 1f | |
| 83 | movl _CNT(IPTR),COUNT /* If not, don't read off the end */ | |
| 84 | 1: | |
| 85 | locc $NL,COUNT,*_PTR(IPTR) /* Scan the buffer */ | |
| 86 | jeql Lagain | |
| 87 | ||
| 88 | /* | |
| 89 | * Success -- copy the data and return. | |
| 90 | */ | |
| 91 | decl r0 /* How many characters did we read? */ | |
| 92 | subl2 r0,COUNT | |
| 93 | movc3 COUNT,*_PTR(IPTR),(S) /* Copy the data */ | |
| 94 | clrb (r3) | |
| 95 | subl2 COUNT,_CNT(IPTR) /* Fix up the I/O buffer */ | |
| 96 | movl r1,_PTR(IPTR) | |
| 97 | ||
| 98 | Lret: | |
| 99 | movl OLD_S,r0 | |
| 100 | ret | |
| 101 | ||
| 102 | /* | |
| 103 | * If we run out of characters, copy the buffer and loop if needed. | |
| 104 | */ | |
| 105 | Lagain: | |
| 106 | movc3 COUNT,*_PTR(IPTR),(S) /* Copy the data */ | |
| 107 | subl2 COUNT,_CNT(IPTR) /* Adjust the buffers and counts */ | |
| 108 | movl r1,_PTR(IPTR) | |
| 109 | subl2 COUNT,N | |
| 110 | movl r3,S | |
| 111 | subl3 $1,N,COUNT | |
| 112 | jgtr Lloop | |
| 113 | ||
| 114 | /* | |
| 115 | * End of file? Check to see if we copied any data. | |
| 116 | */ | |
| 117 | Leof: | |
| 118 | cmpl S,OLD_S | |
| 119 | jeql Lerror | |
| 120 | clrb (S) | |
| 121 | jbr Lret | |
| 122 | ||
| 123 | /* | |
| 124 | * Error return -- null pointer. | |
| 125 | */ | |
| 126 | Lerror: | |
| 127 | clrl r0 | |
| 128 | ret |