C語言面向?qū)ο缶幊痰淖罴褜?shí)踐

一、前言

以STM32為例，打開網(wǎng)絡(luò)上下載的例程或者是購(gòu)買開發(fā)板自帶的例程，都會(huì)發(fā)現(xiàn)應(yīng)用層中會(huì)有stm32f10x.h或者stm32f10x_gpio.h，這些文件嚴(yán)格來時(shí)屬于硬件層的，如果軟件層出現(xiàn)這些文件會(huì)顯得很亂。

使用過Linux的童鞋們肯定知道linux系統(tǒng)無法直接操作硬件層，打開linux或者rt_thread代碼會(huì)發(fā)現(xiàn)代碼中都會(huì)有device的源文件，沒錯(cuò)，這就是驅(qū)動(dòng)層。

二、實(shí)現(xiàn)原理

原理就是將硬件操作的接口全都放到驅(qū)動(dòng)鏈表上，在驅(qū)動(dòng)層實(shí)現(xiàn)device的open、read、write等操作。當(dāng)然這樣做也有弊端，就是驅(qū)動(dòng)find的時(shí)候需要遍歷一遍驅(qū)動(dòng)鏈表，這樣會(huì)增加代碼運(yùn)行時(shí)間。

三、代碼實(shí)現(xiàn)

國(guó)際慣例，寫代碼先寫頭文件。rt_thread中使用的是雙向鏈表，為了簡(jiǎn)單在這我只用單向鏈表。有興趣的可以自行研究rt_thread

頭文件接口:

本次只實(shí)現(xiàn)如下接口，device_open 和device_close等剩下的接口可以自行研究。這樣就可以在應(yīng)用層中只調(diào)用如下接口可實(shí)現(xiàn)：

/*
驅(qū)動(dòng)注冊(cè)
*/
int cola_device_register(cola_device_t *dev);


/*
驅(qū)動(dòng)查找
*/
cola_device_t*cola_device_find(constchar*name);


/*
驅(qū)動(dòng)讀
*/
int cola_device_read(cola_device_t *dev, int pos, void *buffer, int size);


/*
驅(qū)動(dòng)寫
*/
int cola_device_write(cola_device_t *dev, int pos, const void *buffer, int size);


/*
驅(qū)動(dòng)控制
*/
int cola_device_ctrl(cola_device_t *dev, int cmd, void *arg);;

頭文件cola_device.h：

#ifndef_COLA_DEVICE_H_
#define _COLA_DEVICE_H_


enumLED_state
{
  LED_OFF,
  LED_ON,
  LED_TOGGLE,
};


typedefstructcola_devicecola_device_t;
structcola_device_ops
{
  int(*init)(cola_device_t*dev);
  int(*open)(cola_device_t*dev,intoflag);
  int(*close)(cola_device_t*dev);
  int(*read)(cola_device_t*dev,intpos,void*buffer,intsize);
  int(*write)(cola_device_t*dev,intpos,constvoid*buffer,intsize);
  int(*control)(cola_device_t*dev,intcmd,void*args);
};


structcola_device
{
  constchar*name;
  structcola_device_ops*dops;
  structcola_device*next;
};


/*
驅(qū)動(dòng)注冊(cè)
*/
int cola_device_register(cola_device_t *dev);


/*
驅(qū)動(dòng)查找
*/
cola_device_t *cola_device_find(const char *name);


/*
驅(qū)動(dòng)讀
*/
int cola_device_read(cola_device_t *dev, int pos, void *buffer, int size);


/*
驅(qū)動(dòng)寫
*/
int cola_device_write(cola_device_t *dev, int pos, const void *buffer, int size);


/*
驅(qū)動(dòng)控制
*/
int cola_device_ctrl(cola_device_t *dev, int cmd, void *arg);


#endif

源文件cola_device.c：

#include"cola_device.h"
#include
#include 


struct cola_device *device_list = NULL;


/*
查找任務(wù)是否存在
*/
static bool cola_device_is_exists( cola_device_t *dev )
{
  cola_device_t*cur=device_list;
  while(cur!=NULL)
  {
    if(strcmp(cur->name,dev->name)==0)
{
returntrue;
}
cur=cur->next;
}
returnfalse;
}


static int device_list_inster(cola_device_t *dev)
{
  cola_device_t *cur = device_list;
  
  if(NULL==device_list)
  {
    device_list=dev;
    dev->next=NULL;
  }
  else
  {
    while(NULL!=cur->next)
    {
        cur=cur->next;
    }
    
    cur->next=dev;
    dev->next=NULL;
  }
  return1;
}


/*
驅(qū)動(dòng)注冊(cè)
*/
int cola_device_register(cola_device_t *dev)
{
  if((NULL==dev)||(cola_device_is_exists(dev)))
  {
    return0;
  }
  if((NULL==dev->name)||(NULL==dev->dops))
  {
    return0;
  }
  returndevice_list_inster(dev);
}


/*
驅(qū)動(dòng)查找
*/
cola_device_t*cola_device_find(constchar*name)
{
  cola_device_t*cur=device_list;
  while(cur!=NULL)
  {
    if(strcmp(cur->name,name)==0)
    {
      returncur;
    }
    cur=cur->next;
  }
  returnNULL;
}


/*
驅(qū)動(dòng)讀
*/
int cola_device_read(cola_device_t *dev, int pos, void *buffer, int size)
{
  if(dev)
  {
    if(dev->dops->read)
    {
      returndev->dops->read(dev,pos,buffer,size);
    }
  }
  return0;
}


/*
驅(qū)動(dòng)寫
*/
int cola_device_write(cola_device_t *dev, int pos, const void *buffer, int size)
{
  if(dev)
  {
    if(dev->dops->write)
    {
      returndev->dops->write(dev,pos,buffer,size);
    }
  }
  return0;
}


/*
驅(qū)動(dòng)控制
*/
int cola_device_ctrl(cola_device_t *dev, int cmd, void *arg)
{
  if(dev)
  {
    if(dev->dops->control)
    {
      returndev->dops->control(dev,cmd,arg);
    }
  }
  return0;
}

硬件注冊(cè)方式：以LED為例，初始化接口void led_register(void)，需要在初始化中調(diào)用。

#include"stm32f0xx.h"
#include"led.h"
#include"cola_device.h"
#definePORT_GREEN_LEDGPIOC
#define PIN_GREENLED GPIO_Pin_13             


/*LED亮、滅、變化*/
#defineLED_GREEN_OFF(PORT_GREEN_LED->BSRR=PIN_GREENLED)
#defineLED_GREEN_ON(PORT_GREEN_LED->BRR=PIN_GREENLED)
#define LED_GREEN_TOGGLE (PORT_GREEN_LED->ODR ^= PIN_GREENLED)


static cola_device_t led_dev;


static void led_gpio_init(void)
{
  GPIO_InitTypeDefGPIO_InitStructure;
  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOC,ENABLE);
  GPIO_InitStructure.GPIO_Pin=PIN_GREENLED;
  GPIO_InitStructure.GPIO_Mode=GPIO_Mode_OUT;
  GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_OType=GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd=GPIO_PuPd_NOPULL;
  GPIO_Init(PORT_GREEN_LED,&GPIO_InitStructure);
  LED_GREEN_OFF;
}


static int led_ctrl(cola_device_t *dev, int cmd, void *args)
{
  if(LED_TOGGLE==cmd)
  {
    LED_GREEN_TOGGLE;
  }
  else{
  }
  return1;
}


staticstructcola_device_opsops=
{
  .control=led_ctrl,
};


void led_register(void)
{
  led_gpio_init();
  led_dev.dops=&ops;
  led_dev.name="led";
  cola_device_register(&led_dev);
}

應(yīng)用層app代碼:

#include
#include"app.h"
#include"config.h"
#include"cola_device.h"
#include "cola_os.h"


statictask_ttimer_500ms;
static cola_device_t *app_led_dev;


//led每500ms狀態(tài)改變一次
static void timer_500ms_cb(uint32_t event)
{
  cola_device_ctrl(app_led_dev,LED_TOGGLE,0);
}


void app_init(void)
{
  app_led_dev=cola_device_find("led");
  assert(app_led_dev);
  cola_timer_create(&timer_500ms,timer_500ms_cb);
  cola_timer_start(&timer_500ms,TIMER_ALWAYS,500);
}

這樣 app.c 文件中就不需要調(diào)用 led.h 頭文件了，rtt 就是這樣實(shí)現(xiàn)的。

四、總結(jié)

這樣就可以實(shí)現(xiàn)軟硬件分層了，是不是非常好用！

五、代碼下載鏈接

https://gitee.com/schuck/cola_os

審核編輯：劉清