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CPM OPERATING SYSTEMS/CPM 68K/1.0X SOURCES/v102a/clib/blkio.c

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+/***************************************************************************
+ *									    
+ *			   _ b l k i o   F u n c t i o n		    
+ *			   -----------------------------		    
+ *	Copyright 1982,1983 by Digital Research Inc.  All rights reserved.  
+ *									    
+ *	The _blkio function is used to read / write a set of contiguous	    
+ *	sectors in an open file.					    
+ *	Note: if CPM, it will use CP/M function 44 (Set Multi-Sector Count) 
+ *	if os_multisectorio is TRUE (BDOS versions 3.0 and above).	    
+ *	Note 2: if PC-DOS, it will use block read and write functions.	    
+ *									    
+ *	Edits:								    
+ *		8-Dec-83 whf	handle PC-DOS changes.			    
+ *									    
+ *	Calling Sequence:						    
+ *		ret = _blkio(ccbp,sector,buffer,count,bdosfunc);	    
+ *									    
+ *	Where:								    
+ *		ret	=  sectors actually read/written		    
+ *		ccbp	-> the open file channel control block		    
+ *		sector	=  The desired starting sector number		    
+ *		buffer  =  The memory address to begin transfer		    
+ *		count	=  the number of sectors to read/write		    
+ *		bdosfunc=  The BDOS function number (B_READ / B_WRITE)	    
+ *									    
+ ****************************************************************************/
+
+#include	"portab.h"
+#include	"osif.h"
+#include	"osiferr.h"
+#include	"osattr.h"
+
+#define MIN(x,y) ( ((x) < (y)) ? (x) : (y) )
+
+	LONG
+_blkio(ccbp,sector,buffer,count,bdosfunc)
+						/****************************/
+	     FD		*ccbp;			/* open file pointer	    */
+	     LONG	sector;			/* Sector number	    */
+	     BYTE	*buffer;		/* User's buffer area	    */
+	     LONG	count;			/* # of sectors to do	    */
+	     int	bdosfunc;		/* BDOS function to use	    */
+{						/****************************/
+
+#if PCDOS    /*=============================================================*/
+	REG WORD seccnt;			/* number sectors xferred   */
+	WORD _pc_readblk(), _pc_writeblk();	/* functions to read/write  */
+
+	if( bdosfunc == B_READ )
+	     return _pc_readblk(&(ccbp->fcb),sector,buffer,(WORD)count,SECSIZ);
+	else return _pc_writeblk(&(ccbp->fcb),sector,buffer,(WORD)count,SECSIZ);
+}
+
+#endif      /*==============================================================*/
+
+
+#if CPM	    /*==============================================================*/
+	WORD	nsecs;				/* # secs to xfer each time */
+	LONG	seccnt;				/* # sectors processed	    */
+	WORD	xuser;				/* old user number	    */
+	WORD	retcode;			/* return code from BDOS    */
+	WORD	Used_Multisec;			/* flag for resetting msecio*/
+						/****************************/
+	seccnt = 0;				/* Zero count initally	    */
+	Used_Multisec = 0;			/* Haven't used it yet	    */
+	xuser = _chkuser(ccbp->user);		/* Check for changed user # */
+	nsecs = 1;				/* default: xfer singly	    */
+						/*			    */
+	while (count > 0)			/* Until all sectors xferred*/
+	{					/*			    */
+		__OSIF(SETDMA,buffer);		/* Set new DMA address	    */
+
+#if HILO	/*==========================================================*/
+		ccbp->fcb.record = sector;	/* Set new record number    */
+#else		/*----------------------------------------------------------*/
+		ccbp->fcb.record = sector << 8;	/* Set new record number    */
+#endif  	/*==========================================================*/
+
+						/*   Multi Sector I/O xfer? */
+		if( (count > 1  &&  os_multisectorio ) || nsecs > 1 ) 
+		{				/* yes!			    */
+		    if( os_oldmultisec )
+			 nsecs = MIN(16,count);	/* Older version of msecio  */
+		    else nsecs = MIN(128,count);/* Later version of msecio  */
+		    ++Used_Multisec;		/* Flag: need to reset	    */
+		    __OSIF(F_MULTISEC,nsecs);	/* make the call	    */
+		}				/*******		    */
+						/****************************/
+		retcode = __OSIF(bdosfunc,&(ccbp->fcb));/* do the read/write*/
+						/****************************/
+		if(retcode != 0)
+		{				/****************************/
+		    if(nsecs>1)			/* were we trying multi-sec?*/
+		    {				/* yes! do error handling   */
+		      if( os_oldmultisec )	/* Older msecio?	    */
+			 nsecs = __cpmrv >> 12;	/* adjust nsecs read like so*/
+		      else nsecs = __cpmrv >> 8;/* later versions: use AH   */
+		    }				/***			    */
+		    else nsecs = 0;		/* ow. assume 0 secs read   */
+		    seccnt += nsecs;		/* Return nfg		    */
+		    break;			/* Return from bottom	    */
+		}				/****************************/
+						/*			    */
+		sector += nsecs;		/* Increment sector number  */
+		count  -= nsecs;		/* Down count		    */
+		seccnt += nsecs;		/* Bump sector count	    */
+		buffer += nsecs*SECSIZ;		/* Increment address	    */
+	}					/****************************/
+	_uchkuser(ccbp->user,xuser);		/* Reset user # if needed   */
+	if( Used_Multisec )			/* Need to reset msecio?    */
+	    __OSIF(F_MULTISEC,1);		/*   then do so...	    */
+	return(seccnt);				/* All is OK		    */
+}						/****************************/
+#endif	/*==================================================================*/