source: buchla-68k/libcio/read.c@ 5c13d64

Last change on this file since 5c13d64 was 5c13d64, checked in by Thomas Lopatic <thomas@…>, 7 years ago

Use void pointers for mem*() functions.
  • Property mode set to 100644
File size: 4.1 KB
Line 
1/*
2 =============================================================================
3 read.c -- file read functions for the C I/O Library
4 Version 9 -- 1987-10-28 -- D.N. Lynx Crowe
5
6 int
7 read(fd, buff, len)
8 char *buff;
9
10 Reads 'len' bytes from file 'fd' into 'buff'.
11 Returns FAILURE (-1) for errors, number of bytes read
12 if successful.
13
14 int
15 _getsec(fp, buf, len)
16 register struct fcb *fp;
17 char *buf;
18 unsigned len;
19
20 Gets 'len' bytes into 'buf' from file 'fp'.
21 Returns FAILURE (-1) for errors, SUCCESS (0) if successful.
22
23 int
24 _filerd(fp, buffer, len)
25 register struct fcb *fp;
26 char *buffer;
27 unsigned len;
28
29 Reads 'len' bytes into 'buffer' from 'fp'.
30 Returns FAILURE (-1) for errors, number of bytes read
31 if successful.
32
33 =============================================================================
34*/
35
36#define DEBUGIT 0
37
38#include "biosdefs.h"
39#include "io.h"
40#include "errno.h"
41#include "fcntl.h"
42#include "stddefs.h"
43
44#if DEBUGIT
45extern short fsdebug;
46#endif
47
48extern int _badfd(void);
49extern int _conin(char *buff, int len);
50extern int _seek(struct fcb *fcp);
51
52extern void *memcpy(void *vp1, void *vp2, int n);
53
54int _filerd(struct fcb *fp, char *buffer, unsigned len);
55
56static int (*t_read[])() = {
57
58 _badfd, /* 0 - invalid type */
59 _filerd, /* 1 - disk file read */
60 _conin /* 2 - console read */
61};
62
63/*
64
65*/
66
67/*
68 =============================================================================
69 read(fd, buff, len) -- Reads 'len' bytes from file 'fd' into 'buff'.
70 Returns FAILURE (-1) for errors, number of bytes read if successful.
71 =============================================================================
72*/
73
74int read(int fd, char *buff, unsigned len)
75{
76 register struct channel *chp;
77
78 if (fd < 0 OR fd > MAXCHAN) { /* check fd range */
79
80 errno = EBADF; /* bad fd */
81 return(FAILURE);
82 }
83
84 chp = &chantab[fd]; /* point at the channel table */
85 return((*t_read[chp->c_read])(chp->c_arg, buff, len)); /* do the read */
86}
87
88/*
89
90*/
91
92/*
93 =============================================================================
94 _getsec(fp, buf, len) -- Gets 'len' bytes into 'buf' from file 'fp'.
95 Returns FAILURE (-1) for errors, SUCCESS (0) if successful.
96 =============================================================================
97*/
98
99int _getsec(struct fcb *fp, char *buf, unsigned len)
100{
101 if ((errno = ReadRN(fp, Wrkbuf)) NE 0) /* get current sector */
102 return(FAILURE);
103
104 memcpy(buf, Wrkbuf + fp->offset, len); /* move what we need */
105
106 if ((fp->offset = (fp->offset + len) & (BPSEC - 1)) EQ 0) {
107
108 ++fp->curlsn; /* advance the sector number */
109
110 if (_seek(fp) < 0) /* seek to the next sector */
111 return(FAILURE);
112 }
113
114 return(SUCCESS); /* return: all bytes read */
115}
116
117/*
118
119*/
120
121/*
122 =============================================================================
123 _filerd(fp, buffer, len) -- Reads 'len' bytes into 'buffer' from 'fp'.
124 Returns FAILURE (-1) for errors, number of bytes read if successful.
125 =============================================================================
126*/
127
128int _filerd(struct fcb *fp, char *buffer, unsigned len)
129{
130 register unsigned l;
131 register unsigned j, k;
132 register long curpos, newpos;
133
134 l = 0;
135 curpos = fp->offset + (fp->curlsn << FILESHFT);
136 newpos = curpos + len;
137
138#if DEBUGIT
139 if (fsdebug)
140 printf("_filerd(): len=%u, curpos=%ld, newpos=%ld, curlen=%ld\n",
141 len, curpos, newpos, fp->curlen);
142#endif
143
144 if (newpos GT fp->curlen) {
145
146 len = fp->curlen - curpos;
147
148#if DEBUGIT
149 if (fsdebug)
150 printf("_filerd(): len adjusted to %u\n", len);
151#endif
152 }
153
154 if (fp->offset) { /* see if we start in the middle of a sector */
155
156 if ((l = BPSEC - fp->offset) > len) /* see what we need */
157 l = len;
158
159 if (_getsec(fp, buffer, l)) /* read what we can */
160 return(len); /* return if ERROR */
161 }
162
163 if (k = (len - l) / BPSEC) /* see what we still need */
164 if ((j = blkrd(fp, buffer + l, k)) NE 0)
165 return((k - j) * BPSEC + l); /* return bytes read */
166
167 l += k * BPSEC; /* adjust l by what we just read */
168
169 if (l < len) /* see if we still need a partial sector */
170 if (_getsec(fp, buffer + l, len - l)) /* read partial sector */
171 return(l); /* return if ERROR or EOF */
172
173 return(len); /* return - got the whole thing */
174}
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