[f40a309] | 1 | /*
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| 2 | =============================================================================
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| 3 | blkrd.c -- read a block of 0..32767 sectors
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| 4 | Version 10 -- 1988-01-08 -- D.N. Lynx Crowe
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| 5 |
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| 6 | int
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| 7 | blkrd(fcp, buf, ns)
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| 8 | struct fcb *fcp;
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| 9 | char *buf;
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| 10 | int ns;
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| 11 |
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| 12 | Reads 'ns' sectors from file 'fcp' into 'buf'.
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| 13 | Returns the number of unread sectors, or 0 if all were read.
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| 14 |
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| 15 | long
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| 16 | _secrd(buf, rec)
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| 17 | register char *buf;
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| 18 | register short rec;
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| 19 |
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| 20 | Reads a logical sector via the track buffer.
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| 21 | Functionally equivalent to the BIOS B_RDWR read function
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| 22 | with the addition of transparent write-thru track buffering.
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| 23 | =============================================================================
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| 24 | */
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| 25 |
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| 26 | #define DEBUGIT 0
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| 27 |
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[b28a12e] | 28 | #include "ram.h"
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[f40a309] | 29 |
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| 30 | #if TBUFFER
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| 31 |
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| 32 | /*
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| 33 | =============================================================================
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| 34 | _secrd(buf, rec) -- read a logical sector via the track buffer
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| 35 | =============================================================================
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| 36 | */
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| 37 |
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[7258c6a] | 38 | int32_t _secrd(int8_t *buf, int16_t rec)
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[f40a309] | 39 | {
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[7258c6a] | 40 | register int16_t track, side, sector;
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| 41 | int32_t brc;
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[f40a309] | 42 |
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| 43 | if (_thebpb->dspt NE 9) /* make sure we can do this */
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| 44 | return(ERR07);
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| 45 |
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| 46 | if (_thebpb->recsiz NE 512)
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| 47 | return(ERR07);
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| 48 |
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| 49 | track = rec / _thebpb->dspc; /* desired track */
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| 50 | _b_tsec = track * _thebpb->dspc; /* base sector of track */
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| 51 | sector = rec - _b_tsec; /* logical sector in cylinder */
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| 52 |
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| 53 | if (sector GE _thebpb->dspt) { /* adjust sector and side */
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| 54 |
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| 55 | sector -= _thebpb->dspt; /* sector now in track */
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| 56 | side = 1;
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| 57 | _b_tsec += _thebpb->dspt;
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| 58 |
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| 59 | } else {
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| 60 |
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| 61 | side = 0;
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| 62 | }
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| 63 |
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| 64 | #if DEBUGIT
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| 65 | if (fsdebug)
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| 66 | printf("_secrd($%08.8LX, %d): track=%d, side=%d, sector=%d, _b_tsec=%d\n",
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| 67 | buf, rec, track, side, sector, _b_tsec);
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| 68 | #endif
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| 69 |
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| 70 | if ((track NE _b_trak) OR (side NE _b_side)) { /* track in buffer ? */
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| 71 |
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[8973acd] | 72 | if ((brc = BIOS(B_RDWR, 0, &_b_tbuf, _thebpb->dspt, _b_tsec, 0))) {
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[f40a309] | 73 |
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| 74 | _b_trak = -1;
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| 75 | _b_side = -1;
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| 76 | return(brc);
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| 77 | }
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| 78 |
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| 79 | _b_trak = track;
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| 80 | _b_side = side;
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| 81 | }
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| 82 |
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[7258c6a] | 83 | memcpy(buf, (int8_t *)_b_tbuf[sector], 512);
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[f40a309] | 84 | return(0L);
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| 85 | }
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| 86 |
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| 87 | #endif
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| 88 |
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| 89 | /*
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| 90 | =============================================================================
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| 91 | blkrd(fcp, buf, ns) -- read 'ns' sectors from file 'fcp' into 'buf'.
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| 92 | Returns the number of unread sectors, or 0 if all were read.
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| 93 | =============================================================================
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| 94 | */
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| 95 |
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[7258c6a] | 96 | int16_t blkrd(struct fcb *fcp, int8_t *buf, int16_t ns)
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[f40a309] | 97 | {
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[7258c6a] | 98 | register int32_t brc; /* bios return code */
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| 99 | register int16_t rb; /* _nsic return code */
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[f40a309] | 100 |
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| 101 | if (ns < 0) /* can't read a negative number of sectors */
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| 102 | return(ns);
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| 103 |
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| 104 | while (ns--) { /* read a sector at a time */
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| 105 |
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| 106 | #if DEBUGIT
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| 107 | if (fsdebug)
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| 108 | printf("_blkrd(): ns=%d, buf=$%08.8lX, curlsn=%ld, curdsn=%ld, offset=%u\n",
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| 109 | ns, buf, fcp->curlsn, fcp->curdsn, fcp->offset);
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| 110 | #endif
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| 111 |
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| 112 | #if TBUFFER
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[8973acd] | 113 | if ((brc = _secrd(buf, (int16_t)fcp->curdsn))) {
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[f40a309] | 114 | #else
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| 115 | if (brc = BIOS(B_RDWR, 0, buf, 1, (short)fcp->curdsn, 0)) {
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| 116 | #endif
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| 117 |
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| 118 | _berrno = brc; /* log the error */
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| 119 | errno = EIO;
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| 120 | return(ns); /* return unread sector count */
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| 121 | }
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| 122 |
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[8973acd] | 123 | if ((rb = _nsic(fcp, _thebpb, _thefat))) { /* find next sector */
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[f40a309] | 124 |
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| 125 | if (rb EQ -1) /* see if we had an error */
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| 126 | errno = EIO; /* set error number */
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| 127 |
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| 128 | return(ns); /* return unread sector count */
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| 129 | }
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| 130 |
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| 131 | buf += _thebpb->recsiz; /* advance buffer pointer */
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| 132 | }
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| 133 |
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| 134 | return(0); /* return -- all sectors read */
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| 135 | }
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[6262b5c] | 136 |
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