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yap-6.3/H/YapHandles.h
2013-12-15 08:37:10 +00:00

137 lines
3.1 KiB
C

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