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80 lines
3.0 KiB
Plaintext
80 lines
3.0 KiB
Plaintext
1File: IOSYS.C Page 1
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1 /****************************************************************
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2 * *
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3 * CP/M-68K BDOS Disk I/O System Module *
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4 * *
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5 * This module translates from the packet oriented I/O *
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6 * passed from the other BDOS modules into BIOS calls. *
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7 * *
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8 * It includes only one external entry point:
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9 * do_phio() - do physical i/o *
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10 * *
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11 * *
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12 * Configured for Alcyon C on the VAX *
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13 * *
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14 ****************************************************************/
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15
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16 #include "bdosinc.h" /* Standard I/O declarations */
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17
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18 #include "bdosdef.h" /* Type and structure declarations for BDOS */
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19
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20 #include "pktio.h" /* Packet I/O definitions */
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21
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22 #include "biosdef.h" /* Declarations for BIOS entry points */
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23
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24 EXTERN udiv(); /* Assembly language unsigned divide routine */
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25 /* in bdosif.s. It's used because Alcyon C */
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26 /* can't do / or % without an external */
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27
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28 /************************
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29 * do_phio entry point *
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30 ************************/
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31
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32 UWORD do_phio(iop)
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33
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34 REG struct iopb *iop; /* iop is a pointer to a i/o parameter block */
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35
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36 {
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37 MLOCAL UBYTE last_dsk; /* static variable to tell which disk
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38 was last used, to avoid disk selects */
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39 REG struct dph *hdrp; /* pointer to disk parameter header */
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40 REG struct dpb *dparmp; /* pointer to disk parameter block */
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41 REG UWORD rtn; /* return parameter */
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42 UWORD iosect; /* sector number returned from divide rtn */
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43
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44 LOCK /* lock the disk system while doing physical i/o */
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45
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46 rtn = 0;
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47 switch (iop->iofcn)
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48 {
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49 case sel_info:
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50 last_dsk = iop->devnum;
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51 iop->infop = bseldsk(last_dsk, iop->ioflags);
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52 break;
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53
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54 case read:
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55 case write:
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56 if (last_dsk != iop->devnum)
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57 bseldsk((last_dsk = iop->devnum), 0);
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58 /* guaranteed disk is logged on, because temp_sel in
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59 BDOSMAIN does it */
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1File: IOSYS.C Page 2
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60 hdrp = iop->infop;
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61 dparmp = hdrp->dpbp;
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62
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63 bsettrk( udiv( iop->devadr, dparmp->spt, &iosect )
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64 + dparmp->trk_off );
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65 bsetsec( bsectrn( iosect, hdrp->xlt ) );
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66 bsetdma(iop->xferadr);
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67 if ((iop->iofcn) == read) rtn = bread();
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68 else rtn = bwrite(iop->ioflags);
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69 break;
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70
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71 case flush:
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72 rtn = bflush();
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73 }
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74
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75 UNLOCK
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76 return(rtn);
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77 }
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