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CPM OPERATING SYSTEMS/CPM 68K/1.0X SOURCES/v102/clib/sbrk.c

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+/****************************************************************************/
+/*									    */
+/*			     s b r k   F u n c t i o n			    */
+/*			     -------------------------			    */
+/*	Copyright 1982 by Digital Research Inc.  All rights reserved.       */
+/*									    */
+/*	The "sbrk" function is used to allocate memory dynamically.	    */
+/*									    */
+/*	Calling Sequence:						    */
+/*									    */
+/*		addr = sbrk(incr);					    */
+/*									    */
+/*	Where:								    */
+/*		incr	Is the incremental number of bytes to be added to   */
+/*			the program heap area.				    */
+/*									    */
+/*		addr	Is the beginning address of the allocated area.	    */
+/*			-1 is returned if allocation failed		    */
+/*									    */
+/****************************************************************************/
+#include <portab.h>
+EXTERN	BYTE	*_break;			/* Old break address	    */
+						/****************************/
+BYTE	*sbrk(incr)				/*			    */
+	WORD	incr;				/* Incremental storage	    */
+						/*			    */
+{						/****************************/
+REG	BYTE	*t1,*t2;			/* Temporary		    */
+REG	LONG	inc;				/* Temp size increment	    */
+	inc = ((LONG)incr) & 0xffffL;		/* Un sign-extend	    */
+	if(inc & 1)				/* Disallow odd incr's	    */
+		inc++;				/* Round up to next	    */
+						/*			    */
+	t1 = _break;				/* Save the old break	    */
+	t2 = _break + inc;			/* New break value	    */
+						/****************************/
+	if(brk(t2) == FAILURE)			/* Allocate		    */
+		return(FAILURE);		/*	Can't		    */
+						/****************************/
+	return(t1);				/* And return		    */
+}						/****************************/