105 lines
2.7 KiB
C
105 lines
2.7 KiB
C
/**********************************************************************
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The OPTYap Prolog system
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OPTYap extends the Yap Prolog system to support or-parallel tabling
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Copyright: R. Rocha and NCC - University of Porto, Portugal
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File: opt.mavar.h
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version: $Id: opt.mavar.h,v 1.3 2005-05-31 08:24:24 ricroc Exp $
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**********************************************************************/
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#ifdef MULTI_ASSIGNMENT_VARIABLES
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/*
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Set of routines to allow restoring updatable variables when we go *up*
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in the tree. Required by copying, SBA, and tabling. Not required by ACOW.
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*/
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#ifndef OPT_MAVAR_STATIC
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#define OPT_MAVAR_STATIC inline static
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#endif
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#define MAVARS_HASH_SIZE 512
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typedef struct ma_h_entry {
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CELL* addr;
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struct ma_h_entry *next;
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} ma_h_inner_struct;
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typedef struct {
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UInt timestmp;
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struct ma_h_entry val;
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} ma_hash_entry;
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extern ma_hash_entry ma_hash_table[MAVARS_HASH_SIZE];
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extern UInt timestamp; /* an unsigned int */
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OPT_MAVAR_STATIC unsigned int MAVAR_HASH(CELL *);
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OPT_MAVAR_STATIC struct ma_h_entry *ALLOC_NEW_MASPACE(void);
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OPT_MAVAR_STATIC int lookup_ma_var(CELL *);
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OPT_MAVAR_STATIC UInt NEW_MAHASH(ma_h_inner_struct *);
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OPT_MAVAR_STATIC unsigned int
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MAVAR_HASH(CELL *addr) {
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#if SIZEOF_INT_P==8
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return((((unsigned int)((CELL)(addr)))>>3)%MAVARS_HASH_SIZE);
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#else
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return((((unsigned int)((CELL)(addr)))>>2)%MAVARS_HASH_SIZE);
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#endif
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}
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extern ma_h_inner_struct *ma_h_top;
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OPT_MAVAR_STATIC struct ma_h_entry *
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ALLOC_NEW_MASPACE(void)
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{
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ma_h_inner_struct *new = ma_h_top;
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ma_h_top++;
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return(new);
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}
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OPT_MAVAR_STATIC int
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lookup_ma_var(CELL *addr) {
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unsigned int i = MAVAR_HASH(addr);
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struct ma_h_entry *nptr, *optr;
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if (ma_hash_table[i].timestmp != timestamp) {
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ma_hash_table[i].timestmp = timestamp;
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ma_hash_table[i].val.addr = addr;
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ma_hash_table[i].val.next = NULL;
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return(FALSE);
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}
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if (ma_hash_table[i].val.addr == addr)
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return(TRUE);
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optr = &(ma_hash_table[i].val);
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nptr = ma_hash_table[i].val.next;
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while (nptr != NULL) {
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if (nptr->addr == addr) {
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return(TRUE);
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}
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optr = nptr;
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nptr = nptr->next;
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}
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nptr = ALLOC_NEW_MASPACE();
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nptr->addr = addr;
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nptr->next = optr;
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return(FALSE);
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}
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OPT_MAVAR_STATIC UInt
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NEW_MAHASH(ma_h_inner_struct *top) {
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UInt time = ++timestamp;
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if (time == 0) {
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unsigned int i;
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/* damn, we overflowed */
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for (i = 0; i < MAVARS_HASH_SIZE; i++)
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ma_hash_table[i].timestmp = 0;
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time = ++timestamp;
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}
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ma_h_top = top;
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return(time);
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}
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#endif /* MULTI_ASSIGNMENT_VARIABLES */
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