手写简易操作系统(二十)--实现堆内存管理-四、用户调用

/* 初始化系统调用，也就是将syscall_table数组中绑定好确定的函数 */
void syscall_init(void) {
    put_str("syscall_init begin!\n");
    syscall_table[SYS_GETPID] = sys_getpid;
    syscall_table[SYS_WRITE] = sys_write;
    syscall_table[SYS_MALLOC] = sys_malloc;
    syscall_table[SYS_FREE] = sys_free;
    put_str("syscall_init done!\n");
}

/* 申请size字节大小的内存,并返回结果 */
void* malloc(uint32_t size) {
   return (void*)_syscall1(SYS_MALLOC, size);
}

/* 释放ptr指向的内存 */
void free(void* ptr) {
   _syscall1(SYS_FREE, ptr);
}

用户调用的代码和之前的保持一致。

4.1、仿真

仿真的main如下

// os/src/kernel/main.c
#include "print.h"
#include "init.h"
#include "thread.h"
#include "interrupt.h"
#include "console.h"
#include "process.h"
#include "syscall_init.h"
#include "syscall.h"
#include "stdio.h"
#include "memory.h"

void k_thread_a(void*);
void k_thread_b(void*);
void u_prog_a(void);
void u_prog_b(void);

int main(void) {
    put_str("I am kernel\n");
    init_all();
    intr_enable();
    process_execute(u_prog_a, "u_prog_a");
    process_execute(u_prog_b, "u_prog_b");
    thread_start("k_thread_a", k_thread_a, "I am thread_a");
    thread_start("k_thread_b", k_thread_b, "I am thread_b");
    while (1);
    return 0;
}

/* 在线程中运行的函数 */
void k_thread_a(void* arg) {
    void* addr1 = sys_malloc(256);
    void* addr2 = sys_malloc(255);
    void* addr3 = sys_malloc(254);
    printk(" k_thread_a malloc addr:0x%x, 0x%x, 0x%x\n", (int)addr1, (int)addr2, (int)addr3);

    int cpu_delay = 100000;
    while (cpu_delay-- > 0);
    sys_free(addr1);
    sys_free(addr2);
    sys_free(addr3);
    while (1);
}

/* 在线程中运行的函数 */
void k_thread_b(void* arg) {
    void* addr1 = sys_malloc(256);
    void* addr2 = sys_malloc(255);
    void* addr3 = sys_malloc(254);
    printk(" k_thread_b malloc addr:0x%x, 0x%x, 0x%x\n", (int)addr1, (int)addr2, (int)addr3);

    int cpu_delay = 100000;
    while (cpu_delay-- > 0);
    sys_free(addr1);
    sys_free(addr2);
    sys_free(addr3);
    while (1);
}

/* 测试用户进程 */
void u_prog_a(void) {
    void* addr1 = malloc(256);
    void* addr2 = malloc(255);
    void* addr3 = malloc(254);
    printf(" prog_a malloc addr:0x%x, 0x%x, 0x%x\n", (int)addr1, (int)addr2, (int)addr3);

    int cpu_delay = 100000;
    while (cpu_delay-- > 0);
    free(addr1);
    free(addr2);
    free(addr3);
    while (1);
}

/* 测试用户进程 */
void u_prog_b(void) {
    void* addr1 = malloc(256);
    void* addr2 = malloc(255);
    void* addr3 = malloc(254);
    printf(" prog_b malloc addr:0x%x, 0x%x, 0x%x\n", (int)addr1, (int)addr2, (int)addr3);

    int cpu_delay = 100000;
    while (cpu_delay-- > 0);
    free(addr1);
    free(addr2);
    free(addr3);
    while (1);
}