#include <assert.h>
#include <stdlib.h>

#ifndef _STACK_DEFINED

typedef struct
{
    int size;
    int max;
    int count;
    unsigned char* data;
    int top;
}stack;

stack init_stack(int size);
void cleanup_stack(stack* s);
void expand_stack(stack* s, int length);
void top_stack(stack s, void* d);
void push_stack(stack* s, void* d);
void pop_stack(stack* s, void* d);
int empty_stack(stack s);

stack init_stack(int size)
{
    stack s;
    s.size=size;
    s.max=0;
    s.count=0;
    s.data=0;
    s.top=-1;
    return s;
}

void cleanup_stack(stack* s)
{
    s->max=0;
    s->count=0;
    s->data=0;
    s->top=-1;
}

void expand_stack(stack* s, int length)
{
    void* v=realloc(s->data,(s->max+length)*s->size);
    assert(v);
    s->data=v;
    s->max+=length;
}

void top_stack(stack s, void* d)
{
    if(empty_stack(s))
        exit(0);
    memcpy(d,&(s.data[s.top*s.size]),s.size);
}

void push_stack(stack* s, void* d)
{
    if(s->count==s->max)
        expand_stack(s,10);
    memcpy(&(s->data[(s->top+1)*s->size]),d,s->size);
    s->count++;
    s->top++;
}

void pop_stack(stack* s, void* d)
{
    memcpy(d,&(s->data[s->top*s->size]),s->size);
    s->data[s->top*s->size]=0;
    s->top--;
    s->count--;
}

int empty_stack(stack s)
{
    return s.top==-1;
}

#define _STACK_DEFINED
#endif