输出格式要求：实现C90环境下的无溢出系统栈

// 定义栈结构
typedef struct {
    void* stack_base; // 栈底
    void* stack_top;  // 栈顶
    void* current_sp; // 当前栈指针
    size_t stack_size; // 栈大小
    struct Stack* previous_stack; // 前一个栈
} Stack;

// 全局变量，指向当前栈
Stack* current_stack;

// 初始化栈
void init_stack(size_t size) {
    current_stack = (Stack*)malloc(sizeof(Stack));
    current_stack->stack_size = size;
    current_stack->stack_base = malloc(size);
    current_stack->stack_top = (char*)current_stack->stack_base + size;
    current_stack->current_sp = current_stack->stack_top;
    current_stack->previous_stack = NULL;
}

// 栈溢出检测
int check_stack_overflow(size_t required_size) {
    if ((char*)current_stack->current_sp - required_size < (char*)current_stack->stack_base) {
        return 1; // 溢出
    }
    return 0; // 未溢出
}

// 扩展栈
void extend_stack(size_t new_size) {
    // 创建新的栈
    Stack* new_stack = (Stack*)malloc(sizeof(Stack));
    new_stack->stack_size = new_size;
    new_stack->stack_base = malloc(new_size);
    new_stack->stack_top = (char*)new_stack->stack_base + new_size;
    new_stack->current_sp = new_stack->stack_top;
    new_stack->previous_stack = current_stack;

    // 保存当前栈的状态 (例如寄存器，返回地址等，需要汇编实现)
    // ...

    // 切换到新的栈
    current_stack = new_stack;

    // ... (汇编代码修改栈指针)
}

// 函数调用前
void before_function_call(size_t required_stack_space) {
    if (check_stack_overflow(required_stack_space)) {
        extend_stack(current_stack->stack_size * 2); // 扩展栈，大小翻倍
    }
}

// 函数调用后 (需要汇编实现)
void after_function_call() {
    // ... (汇编代码恢复之前的栈)
}

// 示例函数
void my_function(int n) {
    before_function_call(1024); // 假设需要1024字节的栈空间

    if (n > 0) {
        my_function(n - 1);
    }

    after_function_call();
}

int main() {
    init_stack(4096); // 初始栈大小为4096字节
    my_function(100);
    return 0;
}