#include "error.h"
#include "stack.h"

#include <stdlib.h>

int stack_init(struct stack *st, size_t size) {
    st->data = malloc(sizeof(uint64_t) * size);
    if (!st->data) {
        return -ERR_OUT_OF_MEMORY;
    }
    st->size = size;
    st->sp = size;
    return 0;
}
void stack_free(struct stack *st) {
    free(st->data);
    st->data = NULL;
    st->size = 0;
    st->sp = 0;
}
int stack_push(struct stack *st, uint64_t w) {
    if (st->sp == 0) {
        return -ERR_STACK_OVERFLOW;
    }
    st->data[--st->sp] = w;
    return 0;
}
int stack_pop(struct stack *st, uint64_t *w) {
    if (st->sp == st->size) {
        return -ERR_STACK_UNDERFLOW;
    }
    *w = st->data[st->sp++];
    return 0;
}