text: /*************************************************************************
  *									 *
  *	 YAP Prolog 							 *
  *									 *
  *	Yap Prolog was developed at NCCUP - Universidade do Porto	 *
  *									 *
  * Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997	 *
  *									 *
  **************************************************************************
  *									 *
  * File:		absmi.c							 *
  * Last rev:								 *
  * mods:									 *
  * comments:	Portable abstract machine interpreter includes           *
  *									 *
  *************************************************************************/
  
  #ifdef SCCS
  static char SccsId[] = "%W% %G%";
  
  #endif /* SCCS */
  
  #if NATIVE_EXECUTION
  /* just a stub */
  #else
  #define	  EXEC_NATIVE(X)
  #define	  MAX_INVOCATION 1024
  #define	  Yapc_Compile(P) 0
  #endif
  
  /***************************************************************
  * Macros for register manipulation                             *
  ***************************************************************/
  /*
   * Machine and compiler dependent definitions
   */
  #ifdef __GNUC__
  
  #ifdef hppa
  #define SHADOW_P       1
  #define SHADOW_Y       1
  #define SHADOW_REGS    1
  #define USE_PREFETCH   1
  #endif
  
  #ifdef __alpha
  #define SHADOW_P       1
  #define SHADOW_Y       1
  #define SHADOW_REGS    1
  #define USE_PREFETCH   1
  #endif
  
  #ifdef mips
  #define SHADOW_P       1
  #define SHADOW_Y       1
  #define SHADOW_REGS    1
  #define USE_PREFETCH   1
  #endif
  
  #if defined(_POWER) || defined(__POWERPC__)
  #define SHADOW_P       1
  #define SHADOW_REGS    1
  #define USE_PREFETCH   1
  #endif
  
  #ifdef i386
  #define      Y_IN_MEM  1
  #define      S_IN_MEM  1
  #define     TR_IN_MEM  1
  #define HAVE_FEW_REGS  1
  #define LIMITED_PREFETCH   1
  #ifdef BP_FREE
  /***************************************************************
  * Use bp as PREG for X86 machines		               *
  ***************************************************************/
  #if defined(IN_ABSMI_C)
  register struct yami* P1REG asm ("bp"); /* can't use yamop before Yap.h */
  #define PREG P1REG
  #endif
  #define NEEDS_TO_SET_PC 1
  #endif /* BP_FREE */
  #endif /* i386 */
  
  #ifdef sparc
  #define SHADOW_P       1
  #ifdef BP_FREE
  #undef BP_FREE
  #endif
  #define S_IN_MEM       1
  #define      Y_IN_MEM  1
  #define     TR_IN_MEM  1
  #endif /* sparc_ */
  
  #ifdef __x86_64__
  #define SHADOW_P       1
  #ifdef BP_FREE
  #undef BP_FREE
  #endif
  #define SHADOW_S       1
  //#define SHADOW_Y       1
  #define S_IN_MEM       1
  #define      Y_IN_MEM  1
  #define     TR_IN_MEM  1
  #define LIMITED_PREFETCH   1
  #endif /* __x86_64__ */
  
  #else /* other compilers */
  
  #define S_IN_MEM       1
  
  /* This works for xlc under AIX 3.2.5 */
  #ifdef _IBMR2
  #define SHADOW_P       1
  #define SHADOW_REGS    1
  #define SHADOW_S       1
  #endif
  
  #ifdef i386
  #define Y_IN_MEM       1
  #define S_IN_MEM       1
  #define TR_IN_MEM      1
  #define HAVE_FEW_REGS  1
  #endif
  
  #ifdef mips
  #define SHADOW_P       1
  #define SHADOW_Y       1
  #define SHADOW_S       1
  #define SHADOW_CP      1
  #define SHADOW_HB      1
  #define USE_PREFETCH   1
  #endif
  
  #ifdef _HPUX_SOURCE
  #define SHADOW_P       1
  #define SHADOW_Y       1
  #define SHADOW_S       1
  #define SHADOW_CP      1
  #define SHADOW_HB      1
  #define USE_PREFETCH   1
  #endif
  
  #endif /* __GNUC__ */
  
  #include "Yap.h"
  #include "clause.h"
  #include "eval.h"
  #ifdef HAVE_STRING_H
  #include <string.h>
  #endif
  #ifdef YAPOR
  #include "or.macros.h"
  #endif	/* YAPOR */
  #ifdef USE_SYSTEM_MALLOC
  #include "YapHeap.h"
  #endif
  #ifdef TABLING
  #include "tab.macros.h"
  #endif /* TABLING */
  #ifdef LOW_LEVEL_TRACER
  #include "tracer.h"
  #endif
  #include "pl-shared.h"
  #ifdef DEBUG
  /**********************************************************************
   *                                                                    *
   *                 Debugging Auxiliary variables                      *
   *                                                                    *
   **********************************************************************/
  #include <stdio.h>
  #endif
  
  #if PUSH_REGS
  
  /***************************************************************
  * Trick to copy REGS into absmi local environment              *
  ***************************************************************/
  
  /* regp is a global variable */
  
  INLINE_ONLY inline EXTERN void
  init_absmi_regs(REGSTORE * absmi_regs);
  
  INLINE_ONLY inline EXTERN void
  init_absmi_regs(REGSTORE * absmi_regs)
  {
    CACHE_REGS
    memcpy(absmi_regs, Yap_regp, sizeof(REGSTORE));
  }
  
  INLINE_ONLY inline EXTERN void
  restore_absmi_regs(REGSTORE * old_regs);
  
  INLINE_ONLY inline EXTERN void
  restore_absmi_regs(REGSTORE * old_regs)
  {
    CACHE_REGS
    memcpy(old_regs, Yap_regp, sizeof(REGSTORE));
  #ifdef THREADS
    pthread_setspecific(Yap_yaamregs_key, (void *)old_regs);
    LOCAL_ThreadHandle.current_yaam_regs = old_regs;
    LOCAL_PL_local_data_p->reg_cache = old_regs;
  #else
    Yap_regp = old_regs;
  #endif
  }
  #endif /* PUSH_REGS */
  
  /*****************************************************************
  
     Machine Dependent stuff 
  
  ******************************************************************/
  
  #ifdef LONG_LIVED_REGISTERS
  
  #define BEGP(TMP)
  
  #define ENDP(TMP)
  
  #define BEGD(TMP)
  
  #define ENDD(TMP)
  
  #else
  
  #define BEGP(TMP) { register CELL *TMP
  
  #define ENDP(TMP) }
  
  #define BEGD(TMP) { register CELL TMP
  
  #define ENDD(TMP) }
  
  #endif /* LONG_LIVED_REGISTERS */
  
  #define BEGCHO(TMP) { register choiceptr TMP
  
  #define ENDCHO(TMP) }
  
  /***************************************************************
  * YREG is usually, but not always, a register. This affects       *
  * choicepoints                                                 *
  ***************************************************************/
  
  #if Y_IN_MEM
  
  #define CACHE_Y(A) { register CELL *S_YREG = ((CELL *)(A))
  
  #define ENDCACHE_Y() YREG = S_YREG; }
  
  #define B_YREG   ((choiceptr)(S_YREG))
  
  #else
  
  #define S_YREG   (YREG)
  
  #define B_YREG ((choiceptr)(YREG))
  
  #define CACHE_Y(A) { YREG = ((CELL *)(A))
  
  #define ENDCACHE_Y() }
  
  #endif
  
  #if Y_IN_MEM
  
  #define CACHE_Y_AS_ENV(A) { register CELL *ENV_YREG = (A)
  
  #define FETCH_Y_FROM_ENV(A) ENV_YREG = (A)
  
  #define WRITEBACK_Y_AS_ENV()   YREG = ENV_YREG
  
  #define ENDCACHE_Y_AS_ENV() }
  
  #define saveregs_and_ycache() YREG = ENV_YREG; saveregs()
  
  #define setregs_and_ycache() ENV_YREG = YREG; setregs()
  
  #else
  
  #define ENV_YREG (YREG)
  
  #define WRITEBACK_Y_AS_ENV()   
  
  #define CACHE_Y_AS_ENV(A) { YREG = (A)
  
  #define FETCH_Y_FROM_ENV(A) (A)
  
  #define ENDCACHE_Y_AS_ENV() }
  
  #define saveregs_and_ycache() saveregs()
  
  #define setregs_and_ycache() setregs()
  
  #endif
  
  #if S_IN_MEM
  
  #define CACHE_A1()
  
  #define CACHED_A1()	ARG1
  
  #else
  
  #define CACHE_A1()	(SREG = (CELL *)ARG1)
  
  #define CACHED_A1()	((CELL)SREG)
  
  #endif /* S_IN_MEM */
  
  /***************************************************************
  * TR is usually, but not always, a register. This affects      *
  * backtracking                                                 *
  ***************************************************************/
  
  #define CACHE_TR(A) { register tr_fr_ptr S_TR = (A)
  
  #define RESTORE_TR()    TR = S_TR
  
  #define ENDCACHE_TR() }
  
  /***************************************************************
  * S is usually, but not always, a register (X86 machines).     *
  * This affects unification instructions                        *
  ***************************************************************/
  
  #if S_IN_MEM
  
  /* jump through hoops because idiotic gcc will go and read S from
     memory every time it uses S :-( */
  
  #define CACHE_S() { register CELL * S_SREG;
  
  #define ENDCACHE_S() }
  
  #define READ_IN_S() S_SREG = SREG
  
  #else
  
  /* do nothing if you are on a decent machine */
  
  #define CACHE_S() {
  
  #define ENDCACHE_S() }
  
  #define READ_IN_S()
  
  #define S_SREG  SREG
  
  #endif
  
  #define WRITEBACK_S(X) SREG = (X)
  
  /*****************************************************************
  
     End of Machine Dependent stuff 
  
  ******************************************************************/
  
  /*****************************************************************
  
     Prefetch is a technique to obtain the place to jump to before actually
     executing instructions. It can speed up some machines, by having the
     next opcode in place before it is actually required for jumping.
  
  ******************************************************************/
  
  #if USE_THREADED_CODE
  
  #define DO_PREFETCH(TYPE) to_go = (void *)(NEXTOP(PREG,TYPE)->opc)
  
  #define DO_PREFETCH_W(TYPE) to_go = (void *)(NEXTOP(PREG,TYPE)->u.o.opcw)
  
  #if LIMITED_PREFETCH||USE_PREFETCH
  
  #define ALWAYS_START_PREFETCH(TYPE) \
   { register void *to_go; DO_PREFETCH(TYPE)
  
  #define ALWAYS_LOOKAHEAD(WHAT) \
   { register void *to_go = (void *)(WHAT)
  
  #define ALWAYS_START_PREFETCH_W(TYPE) \
   { register void *to_go; DO_PREFETCH_W(TYPE)
  
  #else
  
  #define ALWAYS_START_PREFETCH(TYPE) {
  
  #define ALWAYS_START_PREFETCH_W(TYPE) {
  
  #define ALWAYS_LOOKAHEAD(WHERE) {
  
  #endif
  
  #ifdef USE_PREFETCH
  
  #define START_PREFETCH(TYPE) ALWAYS_START_PREFETCH(TYPE)
  
  #define START_PREFETCH_W(TYPE) ALWAYS_START_PREFETCH_W(TYPE)
  
  #define INIT_PREFETCH() \
       { register void *to_go;
  
  #define PREFETCH_OP(X) \
       to_go = (void *)((X)->opc);
  
  #else
  
  #define START_PREFETCH(TYPE) {
  
  #define START_PREFETCH_W(TYPE) {
  
  #define INIT_PREFETCH() {
  
  #define PREFETCH_OP(X)
  
  #endif	/* USE_PREFETCH */
  
  #else /* USE_THREADED_CODE */
  
  #define ALWAYS_START_PREFETCH(TYPE) {
  
  #define ALWAYS_START_PREFETCH_W(TYPE) {
  
  #define ALWAYS_LOOKAHEAD(WHERE) {
  
  #define START_PREFETCH(TYPE) {
  
  #define START_PREFETCH_W(TYPE) {
  
  #define INIT_PREFETCH() {
  
  #define PREFETCH_OP(X)
  
  #endif /* USE_THREADED_CODE */
  
  #define ALWAYS_END_PREFETCH() }
  
  #define ALWAYS_END_PREFETCH_W() }
  
  #define END_PREFETCH() }
  
  #define END_PREFETCH_W() }
  
  /*****************************************************************
  
    How to jump to the next abstract machine instruction
  
  ******************************************************************/
  
  #if USE_THREADED_CODE
  
  #define JMP(Lab)  goto *Lab 
  
  #define JMPNext()						\
  	JMP((void *)(PREG->opc))
  
  #define JMPNextW()						\
  	JMP((void *)(PREG->u.o.opcw))
  
  #if USE_THREADED_CODE && (LIMITED_PREFETCH || USE_PREFETCH)
  
  #define ALWAYS_GONext() JMP(to_go)
  
  #define ALWAYS_GONextW() JMP(to_go)
  
  #else
  
  #define ALWAYS_GONext() JMPNext()
  
  #define ALWAYS_GONextW() JMPNextW()
  
  #endif
  
  #ifdef USE_PREFETCH
  
  #define GONext() ALWAYS_GONext() 
  
  #define GONextW() ALWAYS_GONextW() 
  
  #else
  
  #define GONext() JMPNext()
  
  #define GONextW() JMPNextW()
  
  #endif /* USE_PREFETCH */
  
  #define Op(Label,Type)	 Label:{ START_PREFETCH(Type)
  
  #define OpW(Label,Type)	 Label: { START_PREFETCH_W(Type)
  
  #define BOp(Label,Type)	 Label: {
  
  #define PBOp(Label,Type) Label: { INIT_PREFETCH()
  
  #define OpRW(Label,Type) Label: {
  
  #else /* do not use threaded code */
  
  #define JMPNext()	goto nextop
  
  #define JMPNextW()	goto nextop_write
  
  #define GONext()	JMPNext()
  
  #define GONextW()	JMPNextW()
  
  #define ALWAYS_GONext() GONext()
  
  #define ALWAYS_GONextW() GONextW()
  
  #define Op(Label,Type)	 case _##Label: { START_PREFETCH(Type)
  
  #define OpW(Label,Type)	 case  _##Label: { START_PREFETCH_W(Type)
  
  #define BOp(Label,Type)	 case _##Label: {
  
  #define PBOp(Label,Type) case _##Label: { INIT_PREFETCH()
  
  #define OpRW(Label,Type) case _##Label: {
  
  #endif
  
  #define ENDOp() END_PREFETCH() }
  
  #define ENDOpW() END_PREFETCH_W() }
  
  #define ENDOpRW() }
  
  #define ENDBOp() }
  
  #define ENDPBOp() END_PREFETCH() }
  
  /**********************************************************************
   *                                                                    *
   *                           PC manipulation                          *
   *                                                                    *
   **********************************************************************/
  
  /*
   * How to set up and move a PC in a nice and disciplined way
   * 
   */
  
  typedef CELL label;
  
  /* move PC */
  
  #define ADJ(P,x)    (P)+ADJUST(sizeof(x))
  
  /*
   * Lookup PredEntry Structure
   * 
   */
  
  #define pred_entry(X)		((PredEntry *)(Unsigned(X)-(CELL)(&(((PredEntry *)NULL)->StateOfPred))))
  #define pred_entry_from_code(X)		((PredEntry *)(Unsigned(X)-(CELL)(&(((PredEntry *)NULL)->CodeOfPred))))
  #define PredFromDefCode(X)	((PredEntry *)(Unsigned(X)-(CELL)(&(((PredEntry *)NULL)->OpcodeOfPred))))
  #define PredFromExpandCode(X)	((PredEntry *)(Unsigned(X)-(CELL)(&(((PredEntry *)NULL)->cs.p_code.ExpandCode))))
  #define PredCode(X)		pred_entry(X)->CodeOfPred
  #define PredOpCode(X)		pred_entry(X)->OpcodeOfPred
  #define TruePredCode(X)		pred_entry(X)->TrueCodeOfPred
  #define PredFunctor(X)		pred_entry(X)->FunctorOfPred
  #define PredArity(X)		pred_entry(X)->ArityOfPE
  #define Module(X)		pred_entry(X)->ModuleOfPred
  
  #define FlagOff(Mask,w) !(Mask&w)
  #define FlagOn(Mask,w) (Mask&w)
  #define ResetFlag(Mask,w) w &= ~Mask
  #define SetFlag(Mask,w) w |= Mask
  
  /**********************************************************************
   *                                                                    *
   *                         X register access                          *
   *                                                                    *
   **********************************************************************/
  
  #if PRECOMPUTE_REGADDRESS
  
  #define XREG(I)		(*(CELL *)(I))
  
  #else
  
  #define XREG(I)		XREGS[I]
  
  #endif /* PRECOMPUTE_REGADDRESS */
  
  /* The Unification Stack is the Auxiliary stack */
  
  #define SP0 ((CELL *)AuxTop)
  #define SP  AuxSp
  
  /**********************************************************************
   *                                                                    *
   *                         RWREG Manipulatio                          *
   *                                                                    *
   **********************************************************************/
  
  #define READ_MODE     1
  #define WRITE_MODE    0
  
  /**********************************************************************
   *                                                                    *
   *Setting Temporary Copies of Often Used WAM registers for efficiency *
   *                                                                    *
   **********************************************************************/
  
  #ifdef SHADOW_P
  #define NEEDS_TO_SET_PC 1
  #endif
  
  /* 
   * First, the PC
   */
  #ifdef NEEDS_TO_SET_PC
  #define set_pc()	PREG = P
  #define save_pc()	P = PREG
  #else
  #define set_pc()
  #define save_pc()
  #define PREG            (P)
  #endif
  
  /* 
   * Next, Y
   */
  #ifdef SHADOW_Y
  #define set_y()		YREG = YENV
  #define save_y()	YENV = YREG
  #else
  #define set_y()
  #define save_y()
  #define YREG            YENV
  #endif
  
  /* 
   * Next, CP
   */
  #ifdef SHADOW_CP
  #define set_cp()	CPREG = CP
  #define save_cp()	CP = CPREG
  #else
  #define set_cp()
  #define save_cp()
  #define CPREG           CP
  #endif
  
  /* Say which registers must be saved at register entry and register
   * exit */
  #define setregs()                     \
  	set_hb();                     \
  	set_cp();                     \
  	set_pc();                     \
          set_y()
  
  #define saveregs()                    \
  	save_hb();                    \
  	save_cp();                    \
  	save_pc();                    \
          save_y()
  
  #if BP_FREE
  /* if we are using BP as a local register, we must save it whenever we leave absmi.c */
  #define always_save_pc()          save_pc()
  #define always_set_pc()           set_pc()
  #else
  #define always_save_pc()
  #define always_set_pc()
  #endif /* BP_FREE */
  
  /************************************************************
  
  Macros to check the limits of stacks
  
  *************************************************************/
  
  #if HAVE_SIGSEGV
  /* for the moment I don't know how to handle trail overflows
     in a pure Windows environment 
  */
  #if !defined(_MSC_VER) && !defined(__MINGW32__) && !defined(THREADS) && !defined(YAPOR) && !defined(USE_SYSTEM_MALLOC) && !USE_DL_MALLOC
  #define OS_HANDLES_TR_OVERFLOW 1
  #endif
  #endif
  
  #ifdef OS_HANDLES_TR_OVERFLOW
  
  #define check_trail(x)
  
  #define check_trail_in_indexing(x)
  
  #else
  
  #define check_trail(x) if (__builtin_expect((Unsigned(CurrentTrailTop) < Unsigned(x)),0)) \
  			goto notrailleft
  
  #define check_trail_in_indexing(x) if (__builtin_expect((Unsigned(CurrentTrailTop) < Unsigned(x)),0)) \
  			goto notrailleft_from_index
  
  #endif
  
  #if (defined(YAPOR_SBA) && defined(YAPOR)) || defined(TABLING)
  #define check_stack(Label, GLOB)                             \
    if (__builtin_expect( ((Int)(Unsigned(YOUNGEST_CP((choiceptr)ENV_YREG,B_FZ)) - Unsigned(YOUNGEST_H(H_FZ,GLOB))) < CreepFlag), 0)  ) goto Label
  #else
  #define check_stack(Label, GLOB)                             \
    if  (__builtin_expect(((Int)(Unsigned(ENV_YREG) - Unsigned(GLOB)) < CreepFlag ), 0) ) goto Label
  #endif /* YAPOR_SBA && YAPOR */
  
  /***************************************************************
  * Macros for choice point manipulation                         *
  ***************************************************************/
  
  /***************************************************************
  * Store variable number of arguments in a choice point         *
  ***************************************************************/
  /***
     pt1 points at the new choice point,
     pt0 points at XREGS[i]
     d0 is a counter
     The macro just pushes the arguments one by one to the local stack.
  ***/
  #define store_args(arity)                                         \
                   BEGP(pt0);                                       \
  		 pt0 = XREGS+(arity);                             \
  		 while ( pt0 > XREGS )                            \
                     { register CELL x = pt0[0];                    \
                       S_YREG = S_YREG-1;			          \
                       --pt0;                                       \
                       (S_YREG)[0] = x;	                          \
  		   }                                              \
                   ENDP(pt0)
  
  #define store_at_least_one_arg(arity)                             \
                   BEGP(pt0);                                       \
  		 pt0 = XREGS+(arity);                             \
                   do { CELL x = pt0[0];                   \
                       S_YREG = (S_YREG)-1;			          \
                       --pt0;                                       \
                       (S_YREG)[0] = x;	                          \
  		   }                                              \
  		 while ( pt0 > XREGS );                           \
                   ENDP(pt0)
  
  #if LOW_LEVEL_TRACER && 0
  #define COUNT_CPS() LOCAL_total_choicepoints++
  #else
  #define COUNT_CPS()
  #endif
  
  /***************************************************************
  * Do the bulk of work in creating a choice-point               *
  * AP: alternative pointer                                      *
  ***************************************************************/
  /*
   * The macro just sets pt1 to point to the base of the choicepoint
   * and then fills in all the necessary fields
   */
  #ifdef DEPTH_LIMIT
  #define store_yaam_reg_cpdepth(CPTR) (CPTR)->cp_depth = DEPTH
  #else
  #define store_yaam_reg_cpdepth(CPTR)
  #endif
  
  #define store_yaam_regs(AP,I) \
                   { /* Jump to CP_BASE */                         \
  		   COUNT_CPS();					       \
                     S_YREG = (CELL *)((choiceptr)((S_YREG)-(I))-1);     \
                     /* Save Information */                        \
  		   HBREG = H;                                    \
                     B_YREG->cp_tr = TR;				 \
                     B_YREG->cp_h  = H;				 \
                     B_YREG->cp_b  = B;				 \
                     store_yaam_reg_cpdepth(B_YREG);               \
                     B_YREG->cp_cp = CPREG;			 \
                     B_YREG->cp_ap = AP;				 \
                     B_YREG->cp_env= ENV;				 \
                   }
  
  #define store_yaam_regs_for_either(AP,d0) \
                  COUNT_CPS();					 \
                   pt1 --; /* Jump to CP_BASE */		         \
                   /* Save Information */                          \
  		 HBREG = H;                                      \
                   pt1->cp_tr = TR;	                         \
                   pt1->cp_h = H;		                         \
  		 pt1->cp_b = B;		                         \
                   store_yaam_reg_cpdepth(pt1);                    \
                   pt1->cp_cp = d0;                                \
                   pt1->cp_ap = AP;                                \
  		 pt1->cp_env = ENV;
  
  /***************************************************************
  * Place B as the new place to cut to                           *
  ***************************************************************/
  #define	  set_cut(E,B) (E)[E_CB] = (CELL)(B)
  
  /***************************************************************
  * Restore WAM registers from a choice point                    *
  ***************************************************************/
  
  #ifdef DEPTH_LIMIT
  #define restore_yaam_reg_cpdepth(CPTR) DEPTH = (CPTR)->cp_depth
  #else
  #define restore_yaam_reg_cpdepth(CPTR)
  #endif
  
  #ifdef YAPOR
  #define YAPOR_update_alternative(CUR_ALT, NEW_ALT)  \
  	  if (SCH_top_shared_cp(B)) {               \
  	    SCH_new_alternative(CUR_ALT, NEW_ALT);  \
  	  } else
  #else
  #define YAPOR_update_alternative(CUR_ALT, NEW_ALT)
  #endif /* YAPOR */
  
  #if defined(FROZEN_STACKS) && !defined(BFZ_TRAIL_SCHEME)
  #define SET_BB(V)    BBREG = (V)
  #else
  #define SET_BB(V)
  #endif /* FROZEN_STACKS && !BFZ_TRAIL_SCHEME */
  
  
  #ifdef FROZEN_STACKS
  #ifdef YAPOR_SBA
  #define PROTECT_FROZEN_H(CPTR)                                  \
         ((Unsigned((Int)((CPTR)->cp_h)-(Int)(H_FZ)) <            \
  	 Unsigned((Int)(B_FZ)-(Int)(H_FZ))) ?                   \
  	(CPTR)->cp_h : H_FZ)
  #define PROTECT_FROZEN_B(CPTR)                                  \
         ((Unsigned((Int)(CPTR)-(Int)(H_FZ)) <                    \
  	 Unsigned((Int)(B_FZ)-(Int)(H_FZ)))  ?                  \
  	(CPTR) : B_FZ)
  	 /*
  #define PROTECT_FROZEN_H(CPTR) ((CPTR)->cp_h > H_FZ && (CPTR)->cp_h < (CELL *)B_FZ ? (CPTR)->cp_h : H_FZ )
  
  #define PROTECT_FROZEN_B(CPTR)  ((CPTR) < B_FZ && (CPTR) > (choiceptr)H_FZ ? (CPTR) : B_FZ )
  	 */
  #else /* TABLING */
  #define PROTECT_FROZEN_B(CPTR)  (YOUNGER_CP(CPTR, B_FZ) ? CPTR        : B_FZ)
  #define PROTECT_FROZEN_H(CPTR)  (((CPTR)->cp_h > H_FZ) ? (CPTR)->cp_h : H_FZ)
  #endif /* YAPOR_SBA */
  #else
  #define PROTECT_FROZEN_B(CPTR)  (CPTR)
  #define PROTECT_FROZEN_H(CPTR)  (CPTR)->cp_h
  #endif /* FROZEN_STACKS */
  
  #define restore_yaam_regs(AP)                                    \
                   { register CELL *x1 = B_YREG->cp_env;	         \
                     register yamop *x2;				 \
                     H = HBREG = PROTECT_FROZEN_H(B_YREG);            \
  		   restore_yaam_reg_cpdepth(B_YREG);	         \
                     CPREG  = B_YREG->cp_cp;		                 \
  		   /* AP may depend on H */			 \
  		   x2 = (yamop *)AP;		                 \
                     ENV    = x1;                                  \
                     YAPOR_update_alternative(PREG, x2)            \
                     B_YREG->cp_ap = x2;                              \
                   }
  
  /***************************************************************
  * Restore variable number of arguments from a choice point     *
  ***************************************************************/
  #define restore_args(Nargs)                                        \
                   BEGD(d0);                                         \
                   d0 = Nargs;                                       \
                   BEGP(pt0);                                        \
                   BEGP(pt1);                                        \
                   pt1 = (CELL *)(B_YREG+1)+d0;                         \
                   pt0 = XREGS+1+d0;                                 \
  	         while (pt0 > XREGS +1 )                           \
                     { register CELL x = pt1[-1];                    \
                       --pt0;                                        \
                       --pt1;                                        \
                       *pt0   = x;                                   \
  		   }                                               \
                   ENDP(pt1);                                        \
                   ENDP(pt0);                                        \
                   ENDD(d0)
  
  #define restore_at_least_one_arg(Nargs)                            \
                   BEGD(d0);                                         \
                   d0 = Nargs;                                       \
                   BEGP(pt0);                                        \
                   BEGP(pt1);                                        \
                   pt1 = (CELL *)(B_YREG+1)+d0;                         \
                   pt0 = XREGS+1+d0;                                 \
                   do { register CELL x = pt1[-1];                   \
                       --pt0;                                        \
                       --pt1;                                        \
                       *pt0   = x;                                   \
  		   }                                               \
  	         while (pt0 > XREGS +1 );                          \
                   ENDP(pt1);                                        \
                   ENDP(pt0);                                        \
                   ENDD(d0)
  
  /***************************************************************
  * Execute trust to release YAAM registers and pop choice point *
  ***************************************************************/
  #ifdef DEPTH_LIMIT
  #define pop_yaam_reg_cpdepth(CPTR) DEPTH = (CPTR)->cp_depth
  #else
  #define pop_yaam_reg_cpdepth(CPTR)
  #endif
  
  #ifdef TABLING
  #define TABLING_close_alt(CPTR) (CPTR)->cp_ap = NULL
  #else
  #define TABLING_close_alt(CPTR)
  #endif /* TABLING */
  
  #define pop_yaam_regs()                                           \
                   {                                                \
                     H = PROTECT_FROZEN_H(B_YREG);                  \
  		   B = B_YREG->cp_b;	                          \
                     pop_yaam_reg_cpdepth(B_YREG);                  \
  		   CPREG = B_YREG->cp_cp;		          \
  		   ENV = B_YREG->cp_env;			  \
                     TABLING_close_alt(B_YREG);	                  \
                     HBREG = PROTECT_FROZEN_H(B);		          \
                   }
  
  #define pop_args(NArgs)                                           \
                   BEGD(d0);                                        \
                   d0 = (NArgs);                                    \
                   BEGP(pt0);                                       \
                   BEGP(pt1);                                       \
                   S_YREG = (CELL *)(B_YREG+1);                     \
                   pt0 = XREGS + 1 ;                                \
                   pt1 = S_YREG ;                                   \
  		 while (pt0 < XREGS+1+d0)                         \
                     { register CELL x = pt1[0];                    \
                       pt1++;                                       \
                       pt0++;                                       \
                       pt0[-1] = x;                                 \
  		   }                                              \
                   S_YREG = pt1;					  \
                   ENDP(pt1);                                       \
                   ENDP(pt0);                                       \
                   ENDD(d0);
  
  #define pop_at_least_one_arg(NArgs)                               \
                   BEGD(d0);                                        \
                   d0 = (NArgs);                                    \
                   BEGP(pt0);                                       \
                   BEGP(pt1);                                       \
                   pt1 = (CELL *)(B_YREG+1);                        \
                   pt0 = XREGS + 1 ;                                \
                   do { register CELL x = pt1[0];                   \
                       pt1++;                                       \
                       pt0++;                                       \
                       pt0[-1] = x;                                 \
  		   }                                              \
  		 while (pt0 < XREGS+1+d0);                        \
                   S_YREG = pt1;	                                  \
                   ENDP(pt1);                                       \
                   ENDP(pt0);                                       \
                   ENDD(d0);
  
  /**********************************************************************
   *                                                                    *
   *                    failure and backtracking                        *
   *                                                                    *
   **********************************************************************/
  
  /* Failure can be called from two routines.
   * 
   * If from within the emulator, we should jump to the label fail.
   * 
   * If from within the complex-term unification routine, we should jump
   * to the label "cufail".
   * 
   */
  
  #define FAIL()	goto fail
  
  /**********************************************************************
   *                                                                    *
   *                      unification routines                          *
   *                                                                    *
   **********************************************************************/
  
  #define UnifyGlobalCells(a, b)                                    \
    if ((b) > (a)) {                                                \
      if (GlobalIsAttVar(b) && !GlobalIsAttVar(a)) {                    \
        Bind_Global((a),(CELL)(b));                                 \
      } else {                                                      \
        Bind_Global((b),(CELL)(a));                                 \
      }                                                             \
    } else if ((b) < (a)) {                                         \
      if (GlobalIsAttVar(a) && !GlobalIsAttVar(b)) {                    \
        Bind_Global((b),(CELL)(a));                                 \
      } else {                                                      \
        Bind_Global((a),(CELL)(b));                                 \
      }                                                             \
    }                                                               
  
  #define UnifyGlobalCellToCell(b, a)	                          \
  if ((a) < H) { /* two globals */				  \
    UnifyGlobalCells(a,b);					  \
  } else {							  \
        Bind_Local((a),(CELL)(b));				  \
  }
  
  #define UnifyCells(a, b)		                          \
  if ((a) < H) { /* at least one global */			  \
    if ((b) > H) { Bind_Local((b),(CELL)(a)); }			  \
    else { UnifyGlobalCells(a,b); }				  \
  } else {                                                          \
    if ((b) > (a)) { Bind_Local((a),(CELL)(b)); }			  \
    else if ((a) > (b)) {						  \
      if ((b) < H) { Bind_Local((a),(CELL)(b)); }                   \
      else { Bind_Local((b),(CELL)(a)); }			          \
    }								  \
  }
  
  /* unify two complex terms.
   * 
   * I use two stacks: one keeps the visited terms, and the other keeps the
   * terms to visit.
   * 
   * The terms-to-visit stack is used to implement traditional
   * recursion. The visited-terms-stack is used to link structures already
   * visited and allows unification of infinite terms
   * 
   */
  
  #ifdef RATIONAL_TREES
  
  #define UNWIND_CUNIF()                                        \
           while (visited < AuxSp) {                            \
              pt1 = (CELL *)visited[0];                         \
              *pt1 = visited[1];                                \
              visited += 2;                                     \
           }
  
  #else
  #define UNWIND_CUNIF()
  #endif
  
  #define UnifyBound_TEST_ATTACHED(f,d0,pt0,d1)                          \
   if (IsExtensionFunctor(f)) {                                          \
     if (unify_extension(f, d0, RepAppl(d0), d1))                        \
          { GONext(); }                                                  \
        else                                                             \
          { FAIL(); }                                                    \
      }
  
  
  #define UnifyBound(d0,d1)                                              \
    if (d0 == d1) GONext();                                              \
    if (IsPairTerm(d0)) {                                                \
      register CELL *ipt0, *ipt1;                                        \
      if (!IsPairTerm(d1)) { FAIL(); }                                   \
      ipt0 = RepPair(d0);                                                \
      ipt1 = RepPair(d1);                                                \
      save_hb();							       \
      always_save_pc();						       \
      if (IUnify_complex(ipt0-1,ipt0+1,ipt1-1)) {always_set_pc(); GONext();}\
      else { FAIL(); }                                                   \
    } else if (IsApplTerm(d0)) {                                         \
      register CELL *ipt0, *ipt1;                                        \
      register Functor f;                                                \
      if (!IsApplTerm(d1)) { FAIL(); }                                   \
      ipt0 = RepAppl(d0);                                                \
      ipt1 = RepAppl(d1);                                                \
      f = (Functor)*ipt0;                                                \
      if (f != (Functor)*ipt1) { FAIL(); }                               \
      UnifyBound_TEST_ATTACHED(f,d0,ipt0,d1);                            \
      d0 = ArityOfFunctor(f);                                            \
      always_save_pc();						       \
      save_hb();							       \
      if (IUnify_complex(ipt0, ipt0+d0, ipt1)) {always_set_pc(); GONext();} \
      else { FAIL(); }                                                   \
    }                                                                    \
    else { FAIL(); }
  
  
  /* 
   * Next, HB
   */
  #ifdef SHADOW_HB
  #undef HBREG
  #define set_hb()	HBREG = HB
  #define save_hb()	HB = HBREG
  #else
  #define set_hb()
  #define save_hb()
  #endif
  
  typedef struct unif_record {
    CELL *ptr;
    Term old;
  } unif_record;
  
  typedef struct v_record {
    CELL *start0;
    CELL *end0;
    CELL *start1;
    Term old;
  } v_record;
  
  #if defined(IN_ABSMI_C) || defined(IN_UNIFY_C)
  
  static int 
  IUnify_complex(CELL *pt0, CELL *pt0_end, CELL *pt1)
  {
    CACHE_REGS
  #ifdef THREADS
  #undef Yap_REGS
    register REGSTORE *regp = Yap_regp;
  #define Yap_REGS (*regp)
  #elif defined(SHADOW_REGS)
  #if defined(B) || defined(TR)
    register REGSTORE *regp = &Yap_REGS;
  
  #define Yap_REGS (*regp)
  #endif /* defined(B) || defined(TR) || defined(HB) */
  #endif
  
  #ifdef SHADOW_HB
    register CELL *HBREG = HB;
  #endif /* SHADOW_HB */
  
    struct unif_record  *unif = (struct unif_record *)AuxBase;
    struct v_record *to_visit  = (struct v_record *)AuxSp;
  #define unif_base ((struct unif_record *)AuxBase)
  #define to_visit_base ((struct v_record *)AuxSp)
  
  loop:
    while (pt0 < pt0_end) {
      register CELL *ptd0 = pt0+1; 
      register CELL d0;
  
      ++pt1;
      pt0 = ptd0;
      d0 = *ptd0;
      deref_head(d0, unify_comp_unk);
    unify_comp_nvar:
      {
        register CELL *ptd1 = pt1;
        register CELL d1 = *ptd1;
  
        deref_head(d1, unify_comp_nvar_unk);
      unify_comp_nvar_nvar:
        if (d0 == d1)
  	continue;
        if (IsPairTerm(d0)) {
  	if (!IsPairTerm(d1)) {
  	  goto cufail;
  	}
  	/* now link the two structures so that no one else will */
  	/* come here */
  	/* store the terms to visit */
  	if (RATIONAL_TREES || pt0 < pt0_end) {
  	  to_visit --;
  #ifdef RATIONAL_TREES
  	  unif++;
  #endif
  	  if ((void *)to_visit < (void *)unif) {
  	    CELL **urec = (CELL **)unif;
  	    to_visit = (struct v_record *)Yap_shift_visit((CELL **)to_visit, &urec, NULL);
  	    unif = (struct unif_record *)urec;
  	  }
  	  to_visit->start0 = pt0;
  	  to_visit->end0 = pt0_end;
  	  to_visit->start1 = pt1;
  #ifdef RATIONAL_TREES
  	  unif[-1].old = *pt0;
  	  unif[-1].ptr = pt0;
  	  *pt0 = d1;
  #endif
  	}
  	pt0_end = (pt0 = RepPair(d0) - 1) + 2;
  	pt1 = RepPair(d1) - 1;
  	continue;
        }
        if (IsApplTerm(d0)) {
  	register Functor f;
  	register CELL *ap2, *ap3;
  
  	if (!IsApplTerm(d1)) {
  	  goto cufail;
  	}
  	/* store the terms to visit */
  	ap2 = RepAppl(d0);
  	ap3 = RepAppl(d1);
  	f = (Functor) (*ap2);
  	/* compare functors */
  	if (f != (Functor) *ap3)
  	  goto cufail;
  	if (IsExtensionFunctor(f)) {
  	  if (unify_extension(f, d0, ap2, d1))
  	    continue;
  	  goto cufail;
  	}
  	/* now link the two structures so that no one else will */
  	/* come here */
  	/* store the terms to visit */
  	if (RATIONAL_TREES || pt0 < pt0_end) {
  	  to_visit --;
  #ifdef RATIONAL_TREES
  	  unif++;
  #endif
  	  if ((void *)to_visit < (void *)unif) {
  	    CELL **urec = (CELL **)unif;
  	    to_visit = (struct v_record *)Yap_shift_visit((CELL **)to_visit, &urec, NULL);
  	    unif = (struct unif_record *)urec;
  	  }
  	  to_visit->start0 = pt0;
  	  to_visit->end0 = pt0_end;
  	  to_visit->start1 = pt1;
  #ifdef RATIONAL_TREES
  	  unif[-1].old = *pt0;
  	  unif[-1].ptr = pt0;
  	  *pt0 = d1;
  #endif
  	}
  	d0 = ArityOfFunctor(f);
  	pt0 = ap2;
  	pt0_end = ap2 + d0;
  	pt1 = ap3;
  	continue;
        }
        goto cufail;
  
        derefa_body(d1, ptd1, unify_comp_nvar_unk, unify_comp_nvar_nvar);
  	/* d1 and pt2 have the unbound value, whereas d0 is bound */
        Bind_Global(ptd1, d0);
        continue;
      }
  
      derefa_body(d0, ptd0, unify_comp_unk, unify_comp_nvar);
      /* first arg var */
      {
        register CELL d1;
        register CELL *ptd1;
  
        ptd1 = pt1;
        d1 = ptd1[0];
        /* pt2 is unbound */
        deref_head(d1, unify_comp_var_unk);
      unify_comp_var_nvar:
        /* pt2 is unbound and d1 is bound */
        Bind_Global(ptd0, d1);
        continue;
  
        derefa_body(d1, ptd1, unify_comp_var_unk, unify_comp_var_nvar);
        /* ptd0 and ptd1 are unbound */
        UnifyGlobalCells(ptd0, ptd1);
      }
    }
    /* Do we still have compound terms to visit */
    if (to_visit < to_visit_base) {
      pt0 = to_visit->start0;
      pt0_end = to_visit->end0;
      pt1 = to_visit->start1;
      to_visit++;
      goto loop;
    }
  #ifdef RATIONAL_TREES
    /* restore bindigs */
    while (unif-- != unif_base) {
      CELL *pt0;
  
      pt0 = unif->ptr;
      *pt0 = unif->old;
    }
  #endif
    return TRUE;
  
  cufail:
  #ifdef RATIONAL_TREES
    /* restore bindigs */
    while (unif-- != unif_base) {
      CELL *pt0;
  
      pt0 = unif->ptr;
      *pt0 = unif->old;
    }
  #endif
    return FALSE;
  #ifdef THREADS
  #undef Yap_REGS
  #define Yap_REGS (*Yap_regp)  
  #elif defined(SHADOW_REGS)
  #if defined(B) || defined(TR)
  #undef Yap_REGS
  #endif /* defined(B) || defined(TR) */
  #endif
  }
  
  /*  don't pollute name space */
  #undef to_visit_base
  #undef unif_base
  
  
  #endif
  
  
  #if defined(IN_ABSMI_C) || defined(IN_INLINES_C)
  
  static int 
  iequ_complex(register CELL *pt0, register CELL *pt0_end,
  	       register CELL *pt1
  )
  {
  CACHE_REGS
  #ifdef THREADS
  #undef Yap_REGS
    register REGSTORE *regp = Yap_regp;
  #define Yap_REGS (*regp)
  #elif defined(SHADOW_REGS)
  #if defined(B) || defined(TR)
    register REGSTORE *regp = &Yap_REGS;
  
  #define Yap_REGS (*regp)
  #endif /* defined(B) || defined(TR) || defined(HB) */
  #endif
  
  #ifdef SHADOW_HB
    register CELL *HBREG = HB;
  #endif /* SHADOW_HB */
  
    struct unif_record  *unif = (struct unif_record *)AuxBase;
    struct v_record *to_visit  = (struct v_record *)AuxSp;
  #define unif_base ((struct unif_record *)AuxBase)
  #define to_visit_base ((struct v_record *)AuxSp)
  
  loop:
    while (pt0 < pt0_end) {
      register CELL *ptd0 = pt0+1; 
      register CELL d0;
  
      ++pt1;
      pt0 = ptd0;
      d0 = *ptd0;
      deref_head(d0, iequ_comp_unk);
    iequ_comp_nvar:
      {
        register CELL *ptd1 = pt1;
        register CELL d1 = *ptd1;
  
        deref_head(d1, iequ_comp_nvar_unk);
      iequ_comp_nvar_nvar:
        if (d0 == d1)
  	continue;
        if (IsPairTerm(d0)) {
  	if (!IsPairTerm(d1)) {
  	  goto cufail;
  	}
  	/* now link the two structures so that no one else will */
  	/* come here */
  	/* store the terms to visit */
  	if (RATIONAL_TREES || pt0 < pt0_end) {
  	  to_visit --;
  #ifdef RATIONAL_TREES
  	  unif++;
  #endif
  	  if ((void *)to_visit < (void *)unif) {
  	    CELL **urec = (CELL **)unif;
  	    to_visit = (struct v_record *)Yap_shift_visit((CELL **)to_visit, &urec, NULL);
  	    unif = (struct unif_record *)urec;
  	  }
  	  to_visit->start0 = pt0;
  	  to_visit->end0 = pt0_end;
  	  to_visit->start1 = pt1;
  #ifdef RATIONAL_TREES
  	  unif[-1].old = *pt0;
  	  unif[-1].ptr = pt0;
  	  *pt0 = d1;
  #endif
  	}
  	pt0_end = (pt0 = RepPair(d0) - 1) + 2;
  	pt1 = RepPair(d1) - 1;
  	continue;
        }
        if (IsApplTerm(d0)) {
  	register Functor f;
  	register CELL *ap2, *ap3;
  
  	if (!IsApplTerm(d1)) {
  	  goto cufail;
  	}
  	/* store the terms to visit */
  	ap2 = RepAppl(d0);
  	ap3 = RepAppl(d1);
  	f = (Functor) (*ap2);
  	/* compare functors */
  	if (f != (Functor) *ap3)
  	  goto cufail;
  	if (IsExtensionFunctor(f)) {
  	  if (unify_extension(f, d0, ap2, d1))
  	    continue;
  	  goto cufail;
  	}
  	/* now link the two structures so that no one else will */
  	/* come here */
  	/* store the terms to visit */
  	if (RATIONAL_TREES || pt0 < pt0_end) {
  	  to_visit --;
  #ifdef RATIONAL_TREES
  	  unif++;
  #endif
  	  if ((void *)to_visit < (void *)unif) {
  	    CELL **urec = (CELL **)unif;
  	    to_visit = (struct v_record *)Yap_shift_visit((CELL **)to_visit, &urec, NULL);
  	    unif = (struct unif_record *)urec;
  	  }
  	  to_visit->start0 = pt0;
  	  to_visit->end0 = pt0_end;
  	  to_visit->start1 = pt1;
  #ifdef RATIONAL_TREES
  	  unif[-1].old = *pt0;
  	  unif[-1].ptr = pt0;
  	  *pt0 = d1;
  #endif
  	}
  	d0 = ArityOfFunctor(f);
  	pt0 = ap2;
  	pt0_end = ap2 + d0;
  	pt1 = ap3;
  	continue;
        }
        goto cufail;
  
        derefa_body(d1, ptd1, iequ_comp_nvar_unk, iequ_comp_nvar_nvar);
  	/* d1 and pt2 have the unbound value, whereas d0 is bound */
        goto cufail;
  
      }
  
      derefa_body(d0, ptd0, iequ_comp_unk, iequ_comp_nvar);
      /* first arg var */
      {
        register CELL d1;
        register CELL *ptd1;
  
        ptd1 = pt1;
        d1 = ptd1[0];
        /* pt2 is unbound */
        deref_head(d1, iequ_comp_var_unk);
      iequ_comp_var_nvar:
        /* pt2 is unbound and d1 is bound */
        goto cufail;
  
        derefa_body(d1, ptd1, iequ_comp_var_unk, iequ_comp_var_nvar);
        /* pt2 and pt3 are unbound */
        if (ptd0 == ptd1)
  	continue;
        goto cufail;
  
      }
    }
    /* Do we still have compound terms to visit */
    if (to_visit < to_visit_base) {
      pt0 = to_visit->start0;
      pt0_end = to_visit->end0;
      pt1 = to_visit->start1;
      to_visit++;
      goto loop;
    }
  #ifdef RATIONAL_TREES
    /* restore bindigs */
    while (unif-- != unif_base) {
      CELL *pt0;
  
      pt0 = unif->ptr;
      *pt0 = unif->old;
    }
  #endif
    return TRUE;
  
  cufail:
  #ifdef RATIONAL_TREES
    /* restore bindigs */
    while (unif-- != unif_base) {
      CELL *pt0;
  
      pt0 = unif->ptr;
      *pt0 = unif->old;
    }
  #endif
    return FALSE;
  #ifdef THREADS
  #undef Yap_REGS
  #define Yap_REGS (*Yap_regp)  
  #elif defined(SHADOW_REGS)
  #if defined(B) || defined(TR)
  #undef Yap_REGS
  #endif /* defined(B) || defined(TR) */
  #endif
  }
  
  #endif
  
  static inline wamreg
  Yap_regnotoreg(UInt regnbr)
  {
  #if PRECOMPUTE_REGADDRESS
    return (wamreg)(XREGS + regnbr);
  #else
  #if MSHIFTOFFS
    return regnbr;
  #else
    return CELLSIZE*regnbr;
  #endif
  #endif /* ALIGN_LONGS */
  }
  
  static inline UInt
  Yap_regtoregno(wamreg reg)
  {
  #if PRECOMPUTE_REGADDRESS
    return ((CELL *)reg)-XREGS;
  #else
  #if MSHIFTOFFS
    return reg;
  #else
    return reg/CELLSIZE;
  #endif
  #endif /* ALIGN_LONGS */
  }
  
  #ifdef DEPTH_LIMIT
  #define check_depth(DEPTH, ap) \
  	  if ((DEPTH) <= MkIntTerm(1)) {/* I assume Module==0 is prolog */ \
  	    if ((ap)->ModuleOfPred) {\
  	      if ((DEPTH) == MkIntTerm(0))\
  		FAIL(); \
  	      else (DEPTH) = RESET_DEPTH();\
  	    } \
  	  } else if ((ap)->ModuleOfPred)\
  	    (DEPTH) -= MkIntConstant(2);
  #else
  #define check_depth(DEPTH, ap)
  #endif
  
  #if defined(THREADS) || defined(YAPOR)
  #define copy_jmp_address(X) (PREG_ADDR = &(X))
  #define copy_jmp_addressa(X) (PREG_ADDR = (yamop **)(X))
  #else
  #define copy_jmp_address(X) 
  #define copy_jmp_addressa(X) 
  #endif
  
  static inline void
  prune(choiceptr cp USES_REGS)
  {
  #ifdef YAPOR
    CUT_prune_to(cp);
  #endif /* YAPOR */
    if (SHOULD_CUT_UP_TO(B,cp))
      {
        if (ASP > (CELL *)PROTECT_FROZEN_B(B))
  	ASP = (CELL *)PROTECT_FROZEN_B(B);
        while (B->cp_b < cp) {
  	if (POP_CHOICE_POINT(B->cp_b))
  	  {
  	    POP_EXECUTE();
  	  }
  	B = B->cp_b;
        }
        if (POP_CHOICE_POINT(B->cp_b))
  	{
  	  POP_EXECUTE();
  	}
        /* cut ! */
  #ifdef TABLING
        abolish_incomplete_subgoals(B);
  #endif /* TABLING */
        HB = PROTECT_FROZEN_H(B->cp_b);
  #include "trim_trail.h"
        B = B->cp_b;
        SET_BB(PROTECT_FROZEN_B(B));
      }
  }
  
  #define SET_ASP(Y,S) SET_ASP__(Y,S PASS_REGS)
  
  static inline
  void SET_ASP__(CELL *yreg, Int sz USES_REGS) {
    ASP = (CELL *) (((char *) yreg) + sz);
    if (ASP > (CELL *)PROTECT_FROZEN_B(B))
      ASP = (CELL *)PROTECT_FROZEN_B(B);
  }
  
  #if YAPOR
  #define INITIALIZE_PERMVAR(PTR, V) Bind_Local((PTR), (V))
  #else
  #define INITIALIZE_PERMVAR(PTR, V) *(PTR) = (V)
  #endif
  
  /* l1: bind a, l2 bind b, l3 no binding */
  #define UnifyAndTrailCells(a, b)                                            \
       if((a) > (b)) {                                                        \
         if ((a) < H) { *(a) = (CELL)(b); DO_TRAIL((a),(CELL)(b)); }	    \
         else if ((b) <= H) { *(a) =(CELL)(b); DO_TRAIL((a),(CELL)(b));}	   \
         else { *(b) = (CELL)(a);  DO_TRAIL((b),(CELL)(a)); }		    \
       } else if((a) < (b)){                                                  \
         if ((b) <= H) { *(b) = (CELL)(a); DO_TRAIL((b),(CELL)(a)); }         \
         else if ((a) <= H) { *(b) = (CELL) (a); DO_TRAIL((b),(CELL)(a));}    \
         else { *(a) = (CELL) (b);  DO_TRAIL((a),(CELL)(b));}                 \
       }
  
  
  #ifdef SHADOW_S
  #define PROCESS_INT( F, C ) \
        BEGD(d0); \
        Yap_REGS.S_ = SREG; \
        saveregs(); \
        d0 = F ( PASS_REGS1 );\
        setregs(); \
        SREG = Yap_REGS.S_; \
        if (!d0) FAIL(); \
        if (d0 == 2) goto C; \
        JMPNext(); \
        ENDD(d0);
  #else
  #define PROCESS_INT( F, C ) \
        BEGD(d0); \
        saveregs(); \
        d0 = F ( PASS_REGS1 );\
        setregs(); \
        if (!d0) FAIL(); \
        if (d0 == 2) goto C; \
        JMPNext(); \
        ENDD(d0);
  #endif
  
  