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36 lines
1.2 KiB
C
36 lines
1.2 KiB
C
/*****************************************************************************
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*
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* C H A N N E L N U M B E R V A L I D A 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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* This routine is used to validate a channel number and return the
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* pointer to the ccb area. The channel must be in range and open.
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*
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* Calling Sequence:
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*
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* ccbptr = _chkc(ch);
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*
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* Where:
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*
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* ch Is the channel number
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* ccbptr Is the returned ccb address
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*
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*****************************************************************************/
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#include <portab.h> /* Include std definitions */
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#include <cpm.h> /* and CP/M definitions */
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#include <errno.h>
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FD *_chkc(ch) /****************************/
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REG UWORD ch; /* Facilitate error check */
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{ /* */
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REG FD *xcb; /* -> CCB */
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/****************************/
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if(ch >= MAXCCBS) /* Is channel in range? */
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RETERR(NULL,EBADF); /* No, quit now. */
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/* */
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xcb = _getccb(ch); /* xcb -> ccb for channel */
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if((xcb->flags & OPENED) == 0) /* Is channel OPEN? */
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RETERR(NULL,EBADF); /* Noooooooo!! */
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return(xcb); /* Else, return pointer */
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} /****************************/
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