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50 lines
1.9 KiB
C
50 lines
1.9 KiB
C
/*****************************************************************************
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*
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* A L L O C C / F R E E C R O U T I N E S
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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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* Routines "allocc" and "freec" are used to allocate / deallocate a
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* channel number so that the user may do I/O directly without the OTS
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* getting in the way.
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* Note that this scheme preserves compatibility with OS's that really
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* truly use channels, and allows users to inform the C Run Time Library
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* routines that they are using the channel.
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* It's not important to use these routines under CP/M, since CP/M
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* allows you to have as many FCBs as you wish.
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*
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* Calling Sequence:
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*
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* i = allocc();
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* freec(i);
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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> /* Also CP/M ones */
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#include <errno.h> /* for error returns */
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LONG _chvec ={0}; /* Allocate storage */
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WORD allocc() /****************************/
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{ /* */
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REG WORD i; /* Define 2 temporaries */
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REG LONG j; /* */
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/* */
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j = 1; /* Start with channel 0 */
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for(i=0;i<MAXCCBS;i++) /* Look at the bits */
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{ /* */
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if((j & _chvec) == 0) /* If 0, then channel free */
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{ /* */
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_chvec |= j; /* set allocated bit */
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return(i); /* and return the channel # */
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} /* */
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j = j << 1; /* Up to next bit */
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} /* End FOR loop */
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RETERR(FAILURE,EMFILE); /* All channels in use! */
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} /****************************/
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WORD freec(ch) /****************************/
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REG WORD ch; /* Channel number to free */
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{ /* */
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_chvec &= ~(1 << ch); /* Clear appropriate bit */
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return(SUCCESS); /* Return OK */
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} /****************************/
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