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