projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 878b8aef KT |
1 | .th GETC III 4/30/72 |
| 2 | .sh NAME | |
| 3 | getc, getw, fopen \*- buffered input | |
| 4 | .sh SYNOPSIS | |
| 5 | .ft B | |
| 6 | mov $filename,r0 | |
| 7 | .br | |
| 8 | jsr r5,fopen; iobuf | |
| 9 | .s3 | |
| 10 | fopen(filename, iobuf) | |
| 11 | .br | |
| 12 | char *filename; | |
| 13 | .br | |
| 14 | struct buf *iobuf; | |
| 15 | .s3 | |
| 16 | jsr r5,getc; iobuf | |
| 17 | .br | |
| 18 | .ft R | |
| 19 | (character in r0) | |
| 20 | .s3 | |
| 21 | .ft B | |
| 22 | getc(iobuf) | |
| 23 | .br | |
| 24 | struct buf *iobuf; | |
| 25 | .s3 | |
| 26 | jsr r5,getw; iobuf | |
| 27 | .br | |
| 28 | .ft R | |
| 29 | (word in r0) | |
| 30 | .s3 | |
| 31 | .ft B | |
| 32 | getw(iobuf) | |
| 33 | .br | |
| 34 | struct buf *iobuf; | |
| 35 | .ft R | |
| 36 | .sh DESCRIPTION | |
| 37 | These routines provide a buffered input | |
| 38 | facility. | |
| 39 | .it Iobuf | |
| 40 | is the address of a 518(10) byte buffer area whose | |
| 41 | contents are maintained by these routines. | |
| 42 | Its structure is | |
| 43 | .s3 | |
| 44 | .nf | |
| 45 | .ft B | |
| 46 | struct buf { | |
| 47 | int fildes; /* File descriptor */ | |
| 48 | int nleft; /* Chars left in buffer */ | |
| 49 | char *nextp; /* Ptr to next character */ | |
| 50 | char buff[512]; /* The buffer */ | |
| 51 | }; | |
| 52 | .ft R | |
| 53 | .s3 | |
| 54 | .fi | |
| 55 | .it Fopen | |
| 56 | may be called initially to open the file. On return, | |
| 57 | the error bit (c-bit) is set if the open failed. | |
| 58 | If \fIfopen\fR is never called, \fIget\fR will | |
| 59 | read from the standard | |
| 60 | input file. | |
| 61 | From C, the value is negative if the open failed. | |
| 62 | .s3 | |
| 63 | .it Getc | |
| 64 | returns the next byte from the file in r0. | |
| 65 | The error bit is set on end of file or a read error. | |
| 66 | From C, the character is returned as an integer, without sign extension; | |
| 67 | it is \*-1 on end-of-file or error. | |
| 68 | .s3 | |
| 69 | \fIGetw\fR returns the next word in r0. | |
| 70 | .it Getc | |
| 71 | and | |
| 72 | \fIgetw\fR | |
| 73 | may be used alternately; there are no odd/even | |
| 74 | problems. | |
| 75 | \fIGetw\fR is may be called from C; | |
| 76 | \*-1 is returned on end-of-file or error, | |
| 77 | but of course | |
| 78 | is also a legitimate value. | |
| 79 | .s3 | |
| 80 | .it Iobuf | |
| 81 | must be provided by the user; it must be on a word boundary. | |
| 82 | .s3 | |
| 83 | To reuse the same buffer for another file, it is sufficient | |
| 84 | to close the original file and call \fIfopen\fR again. | |
| 85 | .sh "SEE ALSO" | |
| 86 | open (II), read (II), getchar (III), putc (III) | |
| 87 | .sh DIAGNOSTICS | |
| 88 | c-bit set on EOF or error; | |
| 89 | from C, negative return indicates error or EOF. | |
| 90 | Moreover, | |
| 91 | .it errno | |
| 92 | is set by this routine just as it is for a system call | |
| 93 | (see introduction (II)). | |
| 94 | .sh BUGS |