mirror of
https://github.com/SEPPDROID/Digital-Research-Source-Code.git
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139 lines
5.7 KiB
C
139 lines
5.7 KiB
C
/***************************************************************************
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*
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* R d b i n F u n c t i o n
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* ---------------------------
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*
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* The "_rdbin" function performs a read operation for binary files.
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*
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* Calling Sequence:
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* ret = _rdbin(fp,buffer,bytes);
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*
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* Where:
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* fp -> to the open CCB
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* buffer -> the user's buffer
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* bytes = the number of bytes to be read
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* ret = the number of bytes actually read
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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 "errno.h"
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WORD _rdbin(fp,buff,bytes) /****************************/
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/* */
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REG FD *fp; /* -> ccb for the file */
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REG BYTE *buff; /* -> buffer to receive data*/
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REG LONG bytes; /* = # bytes to xfer */
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{ /****************************/
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#if CPM /*===============================================================*/
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REG BYTE *p; /* Temp byte pointer */
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LOCAL LONG xsector; /* Temp sector number */
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LOCAL LONG nsector; /* Multi-sector count */
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LOCAL LONG xbytes; /* byte count temp */
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REG LONG i; /* Temp index */
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/****************************/
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xbytes = bytes; /* Preserve org byte cnt */
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xsector = fp->offset >> 7; /* Calculate starting sector*/
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/* */
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if((fp->offset & (SECSIZ-1)) != 0) /* If not on boundary, */
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{ /* must buffer */
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if(fp->sector != xsector) /* Do sectors match? */
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{ /* */
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if((fp->flags & DIRTY) != 0) /* Buffer dirty? */
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{ /* */
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if(_blkio(fp,fp->sector, /* */
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fp->buffer,1L,B_WRITE) != 1) /* Try to write old buffer */
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RETERR(FAILURE,EIO); /* Can't; just quit. */
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fp->flags &= ~DIRTY; /* not dirty anymore */
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} /****************************/
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if(_blkio(fp,xsector,fp->buffer, /* Now read the */
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1L,B_READ) != 1) /* next sector */
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RETERR(FAILURE,EIO); /* Must be EOF */
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fp->sector = xsector; /* Mark buffer */
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} /****************************/
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p = &fp->buffer[(int)fp->offset&(SECSIZ-1)];/* buffer offset */
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/* */
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while(p < &(fp->buffer[SECSIZ]) && /* Move the bytes */
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bytes > 0) /* */
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{ /* */
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*buff++ = *p++; /* Copy data byte */
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bytes--; /* Decrement byte counter */
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fp->offset++; /* Increment offset */
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} /****************************/
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if(bytes == 0) /* Zero byte count now? */
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{ /* */
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if(fp->offset > fp->hiwater) /* Adjust hiwater if */
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fp->hiwater=fp->offset; /* necessary */
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return(xbytes); /* Yes, just return */
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} /* */
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xsector++; /* Bump sector pointer */
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} /****************************/
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/***************************************************************************
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* At this point, a multi-sector transfer may be accomplished. */
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/****************************************************************************/
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/* */
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i = 0; /* In case no xfer */
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nsector = bytes >> 7; /* Compute number of sectors*/
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if(nsector > 0) /* need to transfer?? */
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i=_blkio(fp,xsector,buff,nsector, /* Do the */
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B_READ); /* transfer */
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/* */
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xsector += i; /* Update sector counter */
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fp->offset += i*SECSIZ; /* Update offset */
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bytes -= i*SECSIZ; /* Update byte count */
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buff += i*SECSIZ; /* Update buffer address */
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/* */
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if(fp->offset > fp->hiwater) /* Adjust hiwater */
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fp->hiwater = fp->offset; /* if needed */
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if (i != nsector) /* Short read?? */
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{ /* */
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fp->flags |= ATEOF; /* set EOF Flag */
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return(xbytes - bytes); /* Return actual read count */
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} /****************************/
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if(bytes == 0) /* Done? */
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return(xbytes); /* Yes, return */
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/****************************/
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if((fp->flags & DIRTY) != 0) /* Buffer dirty? */
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{ /* This can be true for */
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if(_blkio(fp,fp->sector, /* boundary conditions */
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fp->buffer,1L,B_WRITE) != 1) /* Try to write old buffer */
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RETERR(FAILURE,EIO); /* Can't; just quit. */
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fp->flags &= ~DIRTY; /* not dirty anymore */
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} /****************************/
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if(_blkio(fp,xsector,fp->buffer,1L, /* Read into buffer */
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B_READ) != 1) /* */
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{ /* */
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fp->flags |= ATEOF; /* End of file */
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return(xbytes-bytes); /* return corrected count */
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} /****************************/
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/* */
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fp->sector = xsector; /* Update data area */
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fp->offset += bytes; /* Increment offset */
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p = &fp->buffer[0]; /* Start with 1st byte */
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while (bytes > 0) /* Count down */
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{ /* bytes */
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*buff++ = *p++; /* Move a byte */
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bytes--; /* Down count */
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} /****************************/
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#endif /*===============================================================*/
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#if PCDOS /*===============================================================*/
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UWORD xbytes; /* More byte count temps */
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/****************************/
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xbytes = _pc_readblk(&(fp->fcb),fp->offset,buff,(WORD)bytes,1); /* */
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if( xbytes==0 ) /* EOF or error condition */
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fp->flags |= ATEOF; /* Set EOF flag */
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fp->offset += xbytes; /* Calculate new offset */
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#endif /*===============================================================*/
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if(fp->offset > fp->hiwater) /* Fix up hiwater mark */
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fp->hiwater = fp->offset; /* */
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return(xbytes); /* Read fully satisfied */
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} /****************************/
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