source: buchla-68k/libcio/read.c@ 4a17aeb

Last change on this file since 4a17aeb was 4a17aeb, checked in by Thomas Lopatic <thomas@…>, 7 years ago

Prototypes for I/O dispatch pointers.
  • Property mode set to 100644
File size: 3.9 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 "ram.h"
39
40static int16_t (*t_read[])(io_arg arg, int8_t *buff, int16_t len) = {
41
42 _badfio, /* 0 - invalid type */
43 _filerd, /* 1 - disk file read */
44 _conin /* 2 - console read */
45};
46
47/*
48
49*/
50
51/*
52 =============================================================================
53 read(fd, buff, len) -- Reads 'len' bytes from file 'fd' into 'buff'.
54 Returns FAILURE (-1) for errors, number of bytes read if successful.
55 =============================================================================
56*/
57
58int16_t read(int16_t fd, int8_t *buff, uint16_t len)
59{
60 register struct channel *chp;
61
62 if (fd < 0 OR fd > MAXCHAN) { /* check fd range */
63
64 errno = EBADF; /* bad fd */
65 return(FAILURE);
66 }
67
68 chp = &chantab[fd]; /* point at the channel table */
69 return((*t_read[chp->c_read])(chp->c_arg, buff, len)); /* do the read */
70}
71
72/*
73
74*/
75
76/*
77 =============================================================================
78 _getsec(fp, buf, len) -- Gets 'len' bytes into 'buf' from file 'fp'.
79 Returns FAILURE (-1) for errors, SUCCESS (0) if successful.
80 =============================================================================
81*/
82
83int16_t _getsec(struct fcb *fp, int8_t *buf, uint16_t len)
84{
85 if ((errno = ReadRN(fp, Wrkbuf)) NE 0) /* get current sector */
86 return(FAILURE);
87
88 memcpy(buf, Wrkbuf + fp->offset, len); /* move what we need */
89
90 if ((fp->offset = (fp->offset + len) & (BPSEC - 1)) EQ 0) {
91
92 ++fp->curlsn; /* advance the sector number */
93
94 if (_seek(fp) < 0) /* seek to the next sector */
95 return(FAILURE);
96 }
97
98 return(SUCCESS); /* return: all bytes read */
99}
100
101/*
102
103*/
104
105/*
106 =============================================================================
107 _filerd(fp, buffer, len) -- Reads 'len' bytes into 'buffer' from 'fp'.
108 Returns FAILURE (-1) for errors, number of bytes read if successful.
109 =============================================================================
110*/
111
112int16_t _filerd(struct fcb *fp, int8_t *buffer, uint16_t len)
113{
114 register uint16_t l;
115 register uint16_t j, k;
116 register int32_t curpos, newpos;
117
118 l = 0;
119 curpos = fp->offset + (fp->curlsn << FILESHFT);
120 newpos = curpos + len;
121
122#if DEBUGIT
123 if (fsdebug)
124 printf("_filerd(): len=%u, curpos=%ld, newpos=%ld, curlen=%ld\n",
125 len, curpos, newpos, fp->curlen);
126#endif
127
128 if (newpos GT fp->curlen) {
129
130 len = fp->curlen - curpos;
131
132#if DEBUGIT
133 if (fsdebug)
134 printf("_filerd(): len adjusted to %u\n", len);
135#endif
136 }
137
138 if (fp->offset) { /* see if we start in the middle of a sector */
139
140 if ((l = BPSEC - fp->offset) > len) /* see what we need */
141 l = len;
142
143 if (_getsec(fp, buffer, l)) /* read what we can */
144 return(len); /* return if ERROR */
145 }
146
147 if (k = (len - l) / BPSEC) /* see what we still need */
148 if ((j = blkrd(fp, buffer + l, k)) NE 0)
149 return((k - j) * BPSEC + l); /* return bytes read */
150
151 l += k * BPSEC; /* adjust l by what we just read */
152
153 if (l < len) /* see if we still need a partial sector */
154 if (_getsec(fp, buffer + l, len - l)) /* read partial sector */
155 return(l); /* return if ERROR or EOF */
156
157 return(len); /* return - got the whole thing */
158}
159
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