mirror of
https://github.com/SEPPDROID/Digital-Research-Source-Code.git
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232 lines
9.9 KiB
Plaintext
232 lines
9.9 KiB
Plaintext
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/****************************************************************************/
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/* */
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/* R e a d F u n c t i o n */
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/* ------------------------- */
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/* Copyright 1982 by Digital Research Inc. All rights reserved. */
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/* */
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/* The read function simulates the UNIX read system call. Any */
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/* arbitrary number of bytes may be read at any arbitrary offset in */
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/* the file. */
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/* The terminal handler for read has been set up to simulate some of */
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/* the functions provided by "ioctl". */
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/* */
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/* Calling Sequence: */
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/* ret = read(fd,buffer,bytes); */
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/* Where: */
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/* ret Is the number of bytes which were actually read */
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/* fd Is an open file descriptor */
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/* buffer Is the buffer address */
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/* bytes Is the number of bytes to read */
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/* */
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/****************************************************************************/
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#include <portab.h>
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#include <cpm.h>
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#include <errno.h>
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WORD read(fd,buff,pbytes) /****************************/
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WORD fd; /* File descriptor */
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REG BYTE *buff; /* -> buffer start */
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WORD pbytes; /* = byte count to read */
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{ /****************************/
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REG FD *fp; /* -> ccb to read from */
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EXTERN LONG _chkc(); /* Converts fd to fp */
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LOCAL LONG ofs; /* Offset temporary */
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LOCAL LONG xbytes; /* Bytes temporary */
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REG LONG xsector; /* Sector temporary */
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REG BYTE c; /* Character temporary */
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REG BYTE *p1; /* Char pointer temporary */
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REG LONG bytes; /* Byte convertor */
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/****************************/
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bytes = (LONG) pbytes; /* Convert to long */
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/* */
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if((LONG)(fp=_chkc(fd)) == FAILURE) /* File open & OK?? */
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return(FAILURE); /* */
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if((fp->flags & ATEOF) != 0) /* End of file already? */
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return(0); /* Yes, quit now */
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if((fp->flags & ISLPT) != 0) /* A wise guy?? */
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RETERR(FAILURE,EBADF); /* A wise guy!! */
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/****************************/
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if((fp->flags & ISTTY) != 0) /* TTY? */
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return(_ttyin(fp,buff,bytes)); /* Yes, read 1 line */
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/****************************/
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if((fp->flags & ISASCII) == 0) /* ASCII?? */
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return(_rdbin(fp,buff,bytes)); /* No, read binary */
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/****************************/
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/****************************************************************************/
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/* Read loop for ASCII data ... */
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/****************************************************************************/
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xbytes = bytes; /* Remember org. request */
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while(bytes > 0) /* Until read is satisfied */
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{ /****************************/
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xsector = fp->offset >> 7; /* Calc starting sector */
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if(xsector != fp->sector) /* Match sector in buffer?? */
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{ /* No, must read first */
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/****************************/
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if((fp->flags & DIRTY) != 0) /* Buffer dirty?? */
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{ /* Yes, must write it */
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if(_blkio(fp,fp->sector,fp->buffer, /* Try to write buffer */
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1L,B_WRITE) != 1) /* */
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RETERR(FAILURE,EIO); /* Unable to write, quit */
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fp->flags &= ~DIRTY; /* Wipe dirty bit */
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} /****************************/
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if(_blkio(fp,xsector,fp->buffer,1L, /* Read proper sector */
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B_READ) != 1) /* */
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{ /* Assume no sparse ascii fs*/
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fp->flags |= ATEOF; /* Set EOF flag */
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return(xbytes-bytes); /* Do partial read */
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}
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fp->sector = xsector; /* Mark buffer correctly */
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} /****************************/
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ofs = fp->offset & (SECSIZ-1); /* correct buffer offset */
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p1 = &(fp->buffer[ofs]); /* Load byte pointer */
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/* */
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while(p1 < &(fp->buffer[SECSIZ]) && /* Ie, more data in buffer */
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bytes > 0) /* And request not satisfied*/
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{ /* */
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c = *p1; /* Pick up next character */
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if(c==EOFCHAR) /* ^Z?? */
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{ /* Yes, */
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fp->flags |= ATEOF; /* Set EOF flag */
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if(fp->offset > fp->hiwater) /* set hiwater mark */
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fp->hiwater = fp->offset; /* if necessary */
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return(xbytes-bytes); /* Return number read */
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} /****************************/
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else if (c == '\r') /* Carriage return? */
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{ /* */
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p1++; /* Yes, just ignore that */
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fp->offset++; /* Increment file offset */
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} /* */
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else /****************************/
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{ /* Regular character */
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*buff++ = c; /* Load buffer with byte */
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bytes--; /* Decrement count */
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p1++; /* increment counter */
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fp->offset++; /* Increment file offset */
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} /****************************/
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} /* */
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} /* While bytes > 0 */
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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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/****************************************************************************/
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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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/* 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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/* */
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/* ret = the number of bytes actually read */
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/* */
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/****************************************************************************/
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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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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[fp->offset&(SECSIZ-1)];/* Compute 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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fp->sector = xsector; /* Mark buffer (MDF) */
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/* */
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fp->offset += bytes; /* Increment offset */
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if(fp->offset > fp->hiwater) /* Adjust high water mark */
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fp->hiwater = fp->offset; /* if necessary */
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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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return(xbytes); /* Return requested length */
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