dynamic_stack.h

/* File:      dynamic_stack.h
** Author(s): Ernie Johnson
** Contact:   xsb-contact@cs.sunysb.edu
** 
** Copyright (C) The Research Foundation of SUNY, 1986, 1993-1998
** 
** XSB is free software; you can redistribute it and/or modify it under the
** terms of the GNU Library General Public License as published by the Free
** Software Foundation; either version 2 of the License, or (at your option)
** any later version.
** 
** XSB is distributed in the hope that it will be useful, but WITHOUT ANY
** WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
** FOR A PARTICULAR PURPOSE.  See the GNU Library General Public License for
** more details.
** 
** You should have received a copy of the GNU Library General Public License
** along with XSB; if not, write to the Free Software Foundation,
** Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
**
** $Id: dynamic_stack.h,v 1.3 2005/01/14 18:30:55 ruim Exp $
** 
*/


#ifndef DYNAMIC_STACK

#define DYNAMIC_STACK



/*-------------------------------------------------------------------------*/

/* Dynamic Stack Structure
   ----------------------- */
typedef struct {
  struct {
    void *top;             /* next available frame */
    void *base;            /* stack bottom */
    void *ceiling;         /* off-end pointer for determining fullness */
  } stack;
  struct {
    size_t frame;          /* size of a frame */
    size_t stackinit;      /* initial size of stack in number of frames */
    size_t stackcur;       /* current size of stack in number of frames */
  } size;
  char *name;
} DynamicStack;

#define DynStk_Top(DS)          ( (DS).stack.top )
#define DynStk_Base(DS)         ( (DS).stack.base )
#define DynStk_Ceiling(DS)      ( (DS).stack.ceiling )
#define DynStk_FrameSize(DS)    ( (DS).size.frame )
#define DynStk_InitSize(DS)     ( (DS).size.stackinit )
#define DynStk_CurSize(DS)      ( (DS).size.stackcur )
#define DynStk_Name(DS)         ( (DS).name )

#define DynStk_NumFrames(DS)    \
   (((char *)DynStk_Top(DS) - (char *)DynStk_Base(DS)) / DynStk_FrameSize(DS))


/* Top-of-Stack Manipulations
   -------------------------- */
#define DynStk_NextFrame(DS)    \
   (void *)((char *)DynStk_Top(DS) + DynStk_FrameSize(DS))
#define DynStk_PrevFrame(DS)    \
   (void *)((char *)DynStk_Top(DS) - DynStk_FrameSize(DS))


/* Stack Maintenance
   ----------------- */
extern void dsPrint(DynamicStack, char *);
extern void dsInit(DynamicStack *, size_t, size_t, char *);
extern void dsExpand(DynamicStack *, int);
extern void dsShrink(DynamicStack *);

#define DynStk_Init(DS,NumElements,FrameType,Desc)      \
   dsInit(DS,NumElements,sizeof(FrameType),Desc)

#define DynStk_ResetTOS(DS)     DynStk_Top(DS) = DynStk_Base(DS)
#define DynStk_IsEmpty(DS)      ( DynStk_Top(DS) == DynStk_Base(DS) )
#define DynStk_IsFull(DS)       ( DynStk_Top(DS) >= DynStk_Ceiling(DS) )

#define DynStk_WillOverflow(DS,NFrames)                         \
   ( (char *)DynStk_Top(DS) + NFrames * DynStk_FrameSize(DS)    \
     > (char *)DynStk_Ceiling(DS) )


#define DynStk_ExpandIfFull(DS) {               \
   if ( DynStk_IsFull(DS) )                     \
     dsExpand(&(DS),1);                         \
 }

#define DynStk_ExpandIfOverflow(DS,N) {         \
   if ( DynStk_WillOverflow(DS,N) )             \
     dsExpand(&(DS),N);                         \
 }


/*
 * In the following macros, "Frame" is assigned a pointer to either
 * the next or the current frame on the stack.
 */

/* Operations With Bounds Checking
   ------------------------------- */
#define DynStk_Push(DS,Frame) {                 \
   DynStk_ExpandIfFull(DS);                     \
   DynStk_BlindPush(DS,Frame);                  \
 }

#define DynStk_Pop(DS,Frame) {                  \
   if ( ! DynStk_IsEmpty(DS) )                  \
     DynStk_BlindPop(DS,Frame)                  \
   else                                         \
     Frame = NULL;                              \
 }

#define DynStk_Peek(DS,Frame) {                 \
   if ( ! DynStk_IsEmpty(DS) )                  \
     DynStk_BlindPeek(DS,Frame);                \
   else                                         \
     Frame = NULL;                              \
 }


/* Operations Without Bounds Checking
   ---------------------------------- */
#define DynStk_BlindPush(DS,Frame) {            \
   Frame = DynStk_Top(DS);                      \
   DynStk_Top(DS) = DynStk_NextFrame(DS);       \
 }

#define DynStk_BlindPop(DS,Frame) {             \
   DynStk_Top(DS) = DynStk_PrevFrame(DS);       \
   Frame = DynStk_Top(DS);                      \
 }

#define DynStk_BlindPeek(DS,Frame)              \
   Frame = DynStk_PrevFrame(DS)

/*-------------------------------------------------------------------------*/


#endif

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