source: buchla-68k/libcio/blkrd.c@ 6262b5c

Last change on this file since 6262b5c was 6262b5c, checked in by Thomas Lopatic <thomas@…>, 7 years ago

Added include files for global functions and variables.
  • Property mode set to 100644
File size: 3.9 KB
Line 
1/*
2 =============================================================================
3 blkrd.c -- read a block of 0..32767 sectors
4 Version 10 -- 1988-01-08 -- D.N. Lynx Crowe
5
6 int
7 blkrd(fcp, buf, ns)
8 struct fcb *fcp;
9 char *buf;
10 int ns;
11
12 Reads 'ns' sectors from file 'fcp' into 'buf'.
13 Returns the number of unread sectors, or 0 if all were read.
14
15 long
16 _secrd(buf, rec)
17 register char *buf;
18 register short rec;
19
20 Reads a logical sector via the track buffer.
21 Functionally equivalent to the BIOS B_RDWR read function
22 with the addition of transparent write-thru track buffering.
23 =============================================================================
24*/
25
26#define DEBUGIT 0
27
28#include "all.h"
29
30/*
31
32*/
33
34#if DEBUGIT
35extern short fsdebug; /* file system debug switch */
36#endif
37
38extern int16_t _nsic(struct fcb *fcp, struct bpb *bpp, int8_t *fp);
39
40extern int32_t _berrno; /* last file system bios error number */
41
42extern uint16_t _thefat[]; /* current file allocation table */
43
44extern struct bpb *_thebpb; /* current bios parameter block */
45
46#if TBUFFER
47
48/* WARNING: this ONLY works for 512 byte sectors, 9 sectors per track */
49
50extern int16_t _b_tbuf[9][256]; /* the track buffer */
51
52extern int16_t _b_trak; /* current track */
53extern int16_t _b_side; /* current side */
54extern int16_t _b_sect; /* current sector */
55extern int16_t _b_tsec; /* current base sector of current track */
56
57#endif
58
59/*
60
61*/
62
63#if TBUFFER
64
65/*
66 =============================================================================
67 _secrd(buf, rec) -- read a logical sector via the track buffer
68 =============================================================================
69*/
70
71int32_t _secrd(int8_t *buf, int16_t rec)
72{
73 register int16_t track, side, sector;
74 int32_t brc;
75
76 if (_thebpb->dspt NE 9) /* make sure we can do this */
77 return(ERR07);
78
79 if (_thebpb->recsiz NE 512)
80 return(ERR07);
81
82 track = rec / _thebpb->dspc; /* desired track */
83 _b_tsec = track * _thebpb->dspc; /* base sector of track */
84 sector = rec - _b_tsec; /* logical sector in cylinder */
85
86 if (sector GE _thebpb->dspt) { /* adjust sector and side */
87
88 sector -= _thebpb->dspt; /* sector now in track */
89 side = 1;
90 _b_tsec += _thebpb->dspt;
91
92 } else {
93
94 side = 0;
95 }
96
97#if DEBUGIT
98 if (fsdebug)
99 printf("_secrd($%08.8LX, %d): track=%d, side=%d, sector=%d, _b_tsec=%d\n",
100 buf, rec, track, side, sector, _b_tsec);
101#endif
102
103 if ((track NE _b_trak) OR (side NE _b_side)) { /* track in buffer ? */
104
105 if (brc = BIOS(B_RDWR, 0, &_b_tbuf, _thebpb->dspt, _b_tsec, 0)) {
106
107 _b_trak = -1;
108 _b_side = -1;
109 return(brc);
110 }
111
112 _b_trak = track;
113 _b_side = side;
114 }
115
116 memcpy(buf, (int8_t *)_b_tbuf[sector], 512);
117 return(0L);
118}
119
120#endif
121
122/*
123
124*/
125
126/*
127 =============================================================================
128 blkrd(fcp, buf, ns) -- read 'ns' sectors from file 'fcp' into 'buf'.
129 Returns the number of unread sectors, or 0 if all were read.
130 =============================================================================
131*/
132
133int16_t blkrd(struct fcb *fcp, int8_t *buf, int16_t ns)
134{
135 register int32_t brc; /* bios return code */
136 register int16_t rb; /* _nsic return code */
137
138 if (ns < 0) /* can't read a negative number of sectors */
139 return(ns);
140
141 while (ns--) { /* read a sector at a time */
142
143#if DEBUGIT
144 if (fsdebug)
145 printf("_blkrd(): ns=%d, buf=$%08.8lX, curlsn=%ld, curdsn=%ld, offset=%u\n",
146 ns, buf, fcp->curlsn, fcp->curdsn, fcp->offset);
147#endif
148
149#if TBUFFER
150 if (brc = _secrd(buf, (int16_t)fcp->curdsn)) {
151#else
152 if (brc = BIOS(B_RDWR, 0, buf, 1, (short)fcp->curdsn, 0)) {
153#endif
154
155 _berrno = brc; /* log the error */
156 errno = EIO;
157 return(ns); /* return unread sector count */
158 }
159
160 if (rb = _nsic(fcp, _thebpb, _thefat)) { /* find next sector */
161
162 if (rb EQ -1) /* see if we had an error */
163 errno = EIO; /* set error number */
164
165 return(ns); /* return unread sector count */
166 }
167
168 buf += _thebpb->recsiz; /* advance buffer pointer */
169 }
170
171 return(0); /* return -- all sectors read */
172}
173
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