132 lines
3.0 KiB
C
132 lines
3.0 KiB
C
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/*************************************************************************
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* *
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* YAP Prolog %W% %G% *
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* Yap Prolog was developed at NCCUP - Universidade do Porto *
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* *
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* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997 *
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* *
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**************************************************************************
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* *
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* File: YapHandles.h *
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* mods: *
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* comments: term handles for YAP: basic ops *
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* version: $Id: Yap.h,v 1.38 2008-06-18 10:02:27 vsc Exp $ *
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*************************************************************************/
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#ifndef YAP_HANDLES_H
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#define YAP_HANDLES_H 1
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/*************************************************************************************************
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slots
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Also known as term handles, they provide a way to access terms without being exposed to stack shifts in gc.
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They should always be used as local variables.
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They are organized as follows:
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---- Tagged Offset of next pointer in chain
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---- Tagged Number of entries
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Entry
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Entry
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Entry
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Entry
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---- Tagged Number of entries
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They are not known to the yaam. Instead,
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they are created when entering user code (see YAP_Execute* functions). They are also created:
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- by SWI PL_foreign_frame function,
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- by YAP_*Goal routines, when they exit successfully. Notice that all handles created by c-goals within
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a *Goal execution should not be used afterwards.
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*************************************************************************************************/
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static inline Int
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Yap_StartSlots( USES_REGS1 ) {
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Int CurSlot = LOCAL_CurSlot;
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// if (CurSlot == LCL0-(ASP+(IntOfTerm(ASP[0])+2)))
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// return CurSlot;
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/* new slot */
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*--ASP = MkIntegerTerm(CurSlot);
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LOCAL_CurSlot = LCL0-ASP;
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*--ASP = MkIntTerm(0);
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*--ASP = MkIntTerm(0);
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return CurSlot;
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}
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static inline Int
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Yap_CurrentSlot( USES_REGS1 ) {
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return IntOfTerm(ASP[0]);
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}
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static inline Term
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Yap_GetFromSlot(Int slot USES_REGS)
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{
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return(Deref(LCL0[slot]));
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}
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static inline Term
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Yap_GetDerefedFromSlot(Int slot USES_REGS)
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{
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return LCL0[slot];
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}
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static inline Term
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Yap_GetPtrFromSlot(Int slot USES_REGS)
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{
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return(LCL0[slot]);
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}
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static inline Term *
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Yap_AddressFromSlot(Int slot USES_REGS)
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{
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return(LCL0+slot);
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}
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static inline void
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Yap_PutInSlot(Int slot, Term t USES_REGS)
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{
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LCL0[slot] = t;
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}
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static inline Int
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Yap_NewSlots(int n USES_REGS)
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{
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Int old_slots = IntOfTerm(ASP[0]), oldn = n;
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while (n > 0) {
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RESET_VARIABLE(ASP);
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ASP--;
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n--;
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}
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ASP[old_slots+oldn+1] = ASP[0] = MkIntTerm(old_slots+oldn);
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return((ASP+1)-LCL0);
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}
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static inline Int
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Yap_InitSlot(Term t USES_REGS)
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{
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Int old_slots = IntOfTerm(ASP[0]);
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*ASP = t;
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ASP--;
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ASP[old_slots+2] = ASP[0] = MkIntTerm(old_slots+1);
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return((ASP+1)-LCL0);
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}
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static inline int
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Yap_RecoverSlots(int n USES_REGS)
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{
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Int old_slots = IntOfTerm(ASP[0]);
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if (old_slots - n < 0) {
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return FALSE;
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}
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ASP += n;
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ASP[old_slots+(n-old_slots+1)] = ASP[0] = MkIntTerm(old_slots-n);
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return TRUE;
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}
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#endif
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