/* $Id$
Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: wielemak@science.uva.nl
WWW: http://www.swi-prolog.org
Copyright (C): 1985-2007, University of Amsterdam
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef PL_SEGSTACK_H_INCLUDED
#define PL_SEGSTACK_H_INCLUDED
#define SEGSTACK_CHUNKSIZE (1*1024)
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
The segchunk struct has its data attached to its back. The data field
itself is typed double to ensure that the data is properly aligned to
allow access of doubles. This is needed to get properly aligned pointers
after topsOfSegStack() in evalExpression().
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
typedef struct segchunk
{ char *top; /* top when closed */
size_t size; /* size of the chunk */
/* below clean using memset() */
int allocated; /* must call free on it */
struct segchunk *next; /* double linked list */
struct segchunk *previous;
double data[1]; /* data on my back */
} segchunk;
#define CHUNK_DATA(c) ((char *)(c)->data)
typedef struct
{ size_t unit_size;
/* below clean using memset() */
segchunk *first;
segchunk *last;
char *base;
char *top;
char *max;
} segstack;
static inline int
emptySegStack(segstack *s)
{ return (s->top == s->base) &&
(s->last == NULL || s->last->previous == NULL);
}
#define popSegStack(stack, to, type) \
( ((stack)->top >= (stack)->base + sizeof(type)) \
? ( (stack)->top -= sizeof(type), \
*to = *(type*)(stack)->top, \
TRUE \
) \
: !(stack)->last || !(stack)->last->previous ? FALSE \
: popSegStack_((stack), to) \
)
#define pushSegStack(stack, data, type) \
( ((stack)->top + sizeof(type) <= (stack)->max) \
? ( *(type*)(stack)->top = data, \
(stack)->top += sizeof(type), \
TRUE \
) \
: pushSegStack_((stack), &data) \
)
COMMON(int) pushSegStack_(segstack *stack, void* data) WUNUSED;
COMMON(int) pushRecordSegStack(segstack *stack, Record r) WUNUSED;
COMMON(int) popSegStack_(segstack *stack, void *data);
COMMON(void*) topOfSegStack(segstack *stack);
COMMON(void) popTopOfSegStack(segstack *stack);
COMMON(void) scanSegStack(segstack *s, void (*func)(void *cell));
COMMON(void) clearSegStack_(segstack *s);
/*******************************
* INLINE *
*******************************/
static inline void
clearSegStack(segstack *s)
{ if ( s->first )
clearSegStack_(s);
}
static inline void
topsOfSegStack(segstack *stack, int count, void **tops)
{ char *p = stack->top - stack->unit_size;
char *base = stack->base;
for(;;)
{ while(count > 0 && p >= base)
{ *tops++ = p;
p -= stack->unit_size;
count--;
}
if ( count > 0 )
{ segchunk *chunk = stack->last->previous;
p = chunk->top - stack->unit_size;
base = CHUNK_DATA(chunk);
} else
break;
}
}
static inline void
initSegStack(segstack *stack, size_t unit_size, size_t len, void *data)
{ stack->unit_size = unit_size;
if ( len )
{ segchunk *chunk = data;
#if O_DEBUG
assert(len > sizeof(*chunk));
assert(unit_size%sizeof(void*) == 0);
#endif
chunk->size = len;
stack->base = stack->top = chunk->top = CHUNK_DATA(chunk);
stack->last = stack->first = chunk;
stack->max = addPointer(chunk, len);
memset(&chunk->allocated, 0,
offsetof(segchunk,data)-offsetof(segchunk,allocated));
} else
{ memset(&stack->first, 0, sizeof(*stack)-offsetof(segstack,first));
}
}
#endif /*PL_SEGSTACK_H_INCLUDED*/