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/*
Copyright (C) 2002 Paul Wilkins
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
/* stack.c by Paul Wilkins */
#include <stdio.h>
#include <stdlib.h>
#include "stack.h"
#include "number.h"
#define STACK_CHUNK_SIZE 20
/* a stack element */
struct StackElem {
struct StackElem *t; /* the node above us */
struct StackElem *b; /* the node below us */
Number *data; /* the data */
};
/* we build the stack in these arrays */
struct StackChunk {
int freeIndx;
struct StackElem *freeList[STACK_CHUNK_SIZE];
struct StackChunk *next;
struct StackElem ary[STACK_CHUNK_SIZE];
};
/* The main stack of GRPN. This is where we store the numbers */
struct Stack stack;
struct StackChunk *stackChunkHead = NULL;
struct Stack *getStack(){
return &stack;
}
/* get the length of the stack */
int stackLen(){
return stack.length;
}
/* malloc a new stack chunk */
struct StackChunk * newStackChunk(){
int i;
struct StackChunk *c;
/* malloc a new chunk */
if(NULL == (c=(struct StackChunk *)malloc(sizeof(struct StackChunk)))){
perror("Malloc");
exit(0);
}
/* initalize stuff */
c->freeIndx = STACK_CHUNK_SIZE - 1;
c->next = NULL;
for(i=0; i<STACK_CHUNK_SIZE; i++){
c->freeList[i] = &((c->ary)[i]);
c->ary[i].data = NULL;
}
return c;
}
/* malloc a new stack element */
struct StackElem * newStackEle(){
struct StackElem *s;
struct StackChunk *c;
/* find the first stack chunk with free elements */
for(c=stackChunkHead; c->freeIndx==-1; c=c->next);
/* get the StackEle */
s = c->freeList[c->freeIndx];
c->freeIndx--;
/* if there are no more free elements */
if(c->freeIndx < 0){
c->freeIndx = -1;
if(c->next == NULL) c->next = newStackChunk();
}
return s;
}
void stackAddToFreeList(struct StackElem *s){
struct StackChunk *c;
for(c=stackChunkHead; c!=NULL; c=c->next)
if(s >= c->ary && s <= &((c->ary)[STACK_CHUNK_SIZE]))
c->freeList[++(c->freeIndx)] = s;
}
int copyStack(struct Stack *srcStack, struct Stack *dstStack, int nelts){
int i;
struct StackElem *dst, *src;
for(i=0, src=srcStack->head;
i<nelts && src;
i++, src=src->t){
/* set the stuff in the newly created stack element */
dst = newStackEle();
dst->data = src->data;
dst->t = dstStack->head;
dst->b = NULL;
incRefcntNumber(dst->data);
/* update the stuff in the ele above us */
if(dst->t) dst->t->b = dst;
/* update the dest stack */
dstStack->head = dst;
dstStack->length++;
}
if(i != nelts){
fprintf(stderr, "copyStack: Error copying stack.\n");
return 0;
}
return 1;
}
int setup_stack(){
stack.head = NULL;
stack.length = 0;
stackChunkHead = newStackChunk();
return 1;
}
void clearNamedStack(struct Stack *stk){
struct StackElem *s;
for(s=stk->head; s; s=s->t){
decRefcntNumber(s->data);
freeNumber(s->data);
stackAddToFreeList(s);
}
stk->head = NULL;
stk->length = 0;
}
void clearStack(){
clearNamedStack(&stack);
}
void printStack(){
char *c;
struct StackElem *s = NULL;
struct StackElem *p = NULL;
/* find the top of the stack */
for(s=stack.head; s; s=s->t) p = s;
/* print the numbers starting from the top */
for(s=p; p; p=p->b){
c = printNumber(p->data);
printf("%s\n", c);
free(c);
}
}
Number * getStackEle(int which){
int i;
struct StackElem *s = NULL;
if(which < 0 || which >= stack.length) return NULL;
s = stack.head;
for(i=0; i<which; i++) s = s->t;
return s->data;
}
int Push(Number *data){
struct StackElem *s;
/* set the stuff in the newly created stack element */
s = newStackEle();
s->data = data;
s->t = stack.head;
s->b = NULL;
/* increment the ref count of the number */
incRefcntNumber(data);
/* update the stuff in the ele above us */
if(s->t) s->t->b = s;
/* update the head */
stack.head = s;
stack.length++;
return 1; /* success */
}
Number * Pop(){
Number *ptr;
struct StackElem *s;
s = stack.head;
/* nothing to pop */
if(s == NULL) return NULL;
/* update the stuff in the ele above us */
if(s->t){
s->t->b = NULL;
stack.head = s->t;
}
else stack.head = NULL;
ptr = s->data;
/* decrement the ref count of the number */
decRefcntNumber(ptr);
stackAddToFreeList(s);
stack.length--;
return ptr;
}
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