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