/** * stack.c -- Implementation of stack that can store anything. * Create: Xie Han, net lab of Peking University <e@pku.edu.cn> * * Simple is the best! * * Created: Sep 30 1:10am 2003. version 1.0.0 * Last updated: Apr 6 9:05pm 2005. version 2.2.1 */#include <stdlib.h>#include "stack.h"stack_t *stack_create(unsigned int init_size){	stack_t *stack = (stack_t *)malloc(sizeof (stack_t));	if (stack)	{		if (stack->base = (char *)malloc(init_size))		{			stack->top = stack->base;			stack->end = stack->base + init_size;		}		else		{			free(stack);			stack = NULL;		}	}	return stack;}int __stack_expand(unsigned int elem_size, stack_t *stack){	unsigned int new_size = stack->end - stack->base;	char *new_base;	if (new_size > 0)		new_size <<= 1;	else		new_size = STACK_INITIAL_SIZE;	while (stack->top + elem_size > stack->base + new_size)		new_size <<= 1;	if (new_base = (char *)realloc(stack->base, new_size))	{		stack->top = stack->top - stack->base + new_base;		stack->base = new_base;		stack->end = stack->base + new_size;		return new_size;	}	return -1;}void stack_destroy(stack_t *stack){	free(stack->base);	free(stack);}