嵌入式Linux下完成LCD屏文字显示(帧缓冲框架)

Posted DS小龙哥

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1.前言

帧缓冲框架是Linux下专门为显示类设备设计的接口,目的是将硬件和软件层分离开,方便应用层的编程,也方便应用层程序移植。帧缓冲框架向驱动层和应用层分别提供了一套标准接口,驱动层按照框架编写驱动,应用层按照框架编写应用程序。帧缓冲在/dev目录下生成的标准节点是fb,比如:/dev/fb0,/dev/fb1等等。

这篇文章就介绍在应用层 如何利用帧缓冲框架接口封装LCD屏的画点函数,获取LCD屏的硬件信息,完成对LCD屏编程,实现文字、数字显示。当期的文字采用点阵方式取模来完成显示,比较简单,与单片机上的LCD编程思路一样,可以更方便快速学习帧缓冲编程。后续正常开发中一般采用矢量字库完成字体显示,大小调整方便,字体更换方法,在前面文章有介绍过嵌入式Linux如何交叉编译freetype库。

2. 编程思路

下面是帧缓冲框架图:

帧缓冲设备是标准的字符设备,通过open函数打开设备,再通过ioctl接口获取LCD屏的一些硬件参数信息,在利用mmap函数映射LCD屏的地址到应用层。映射的这个地址就相当于是LCD屏的显存地址,对这个地址里写入数据就可以在LCD屏硬件上实时显示出来。

int fd=open("/dev/fb0",O_RDWR);
    if(fd<0)
    
        perror("设备文件打开失败");
        return 0;
    

    /*1. 获取LCD屏的可变形参*/
    ioctl(fd,FBIOGET_VSCREENINFO,&var);
    printf("分辨率:%d*%d\\n",var.xres,var.yres);
    printf("像素点位数:%d\\n",var.bits_per_pixel);

    /*2. 获取LCD屏的固定形参*/
    ioctl(fd,FBIOGET_FSCREENINFO,&fix);
    printf("映射的长度:%d\\n",fix.smem_len);
    printf("一行的字节数:%d\\n",fix.line_length);

    /*3. 映射LCD缓冲区地址到进程空间*/
    fb_mem=mmap(NULL,fix.smem_len,PROT_READ|PROT_WRITE,MAP_SHARED,fd,0);
    if(fb_mem==NULL)
    
        perror("空间映射失败!\\n");
        return 0;
    

在应用mmap函数将驱动的DMA缓冲区地址映射到进程空间之后,如何控制LCD呢?
为了方便对LCD屏进行操作,需要封装一个画点函数。然后后续的图片显示,文字显示,其他图形显示都基于这个画点函数来完成,程序就很好设计。

当前采用的LCD屏是800*480分辨率,24位像素,通过这些参数就可以编写一个公式,封装画点函数。

下面是封装好的函数原型:fb_mem是LCD屏映射的地址,后面的参数是获取的LCD屏硬件参数信息。

/*
函数功能: 画点
*/
void Show_Pixel(int x,int y,int color)

    unsigned int *lcd=(unsigned int *)(fb_mem+y*var.xres*var.bits_per_pixel/8+x*var.bits_per_pixel/8);
    *lcd=color; //颜色赋值

有了画点函数,就可以封装中文显示函数: 下面这个函数是针对横向取模的点阵字模进行描点的,其他取模方式根据情况修改即可。

/*
函数功能: 显示中文
说明:  取模的字体是按照横向取模进行取点阵码。
       取模的字体宽度是8的倍数。
*/
void ShowFont(int x,int y,int size,unsigned char *data)

    int i,j,x0=x;
    unsigned char tmp;
    for(i=0;i<size/8*size;i++)
    
        tmp=data[i];
        for(j=0;j<8;j++)
        
            if(tmp&0x80)Show_Pixel(x0,y,0xFF0033);
            //else 画背景色
            x0++;
            tmp<<=1;
        
        if(x0-x==size)
        
            y++;
            x0=x;
        
    

中文可以显示,照着思路再封装一个字母数字的显示接口:

/*
函数功能:  显示一个ASCII码。“空格开始 到  ~ 结束”
 !"#$%&()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz|~

说明: ASCII码取模 宽度和高度必须是8的倍数,传入的size(高)
 */
void ShowASCII(int x,int y,int size,unsigned char c_data)

    int i,j,x0=x;
    unsigned char data;
    int cnt;
    if(c_data<  ||  c_data > ~)return; 
    cnt=c_data- ;
    for(i=0;i<size/2/8*size;i++)
    
         switch(size)
         
            case 16:
                break;
             case 32:
                data=ASCII_16_32[cnt][i];
                break;
         
         for(j=0;j<8;j++)
         
             if(data&0x80)Show_Pixel(x0,y,0xFF0033);
             x0++;
             data<<=1;
         
         if(x0-x==size/2)
         
             x0=x;
             y++;
         
    

3. 完整示例代码

3.1 中文显示

下面这份代码是单个汉字取模进行显示的,代码较少,整体比较简单。

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/fb.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <string.h>

struct fb_var_screeninfo var;   //可变参数
struct fb_fix_screeninfo fix;   //固定参数
unsigned char *fb_mem=NULL;     //LCD屏的首地址
extern unsigned char font[];

/*
函数功能: 画点
*/
void Show_Pixel(int x,int y,int color)

    unsigned int *lcd=(unsigned int *)(fb_mem+y*var.xres*var.bits_per_pixel/8+x*var.bits_per_pixel/8);
    *lcd=color; //颜色赋值


/*
函数功能: 显示中文
说明:  取模的字体是按照横向取模进行取点阵码。
       取模的字体宽度是8的倍数。
*/
void ShowFont(int x,int y,int size,unsigned char *data)

    int i,j,x0=x;
    unsigned char tmp;
    for(i=0;i<size/8*size;i++)
    
        tmp=data[i];
        for(j=0;j<8;j++)
        
            if(tmp&0x80)Show_Pixel(x0,y,0xFF0033);
            //else 画背景色
            x0++;
            tmp<<=1;
        
        if(x0-x==size)
        
            y++;
            x0=x;
        
    


int main(int argc,char **argv)

    int fd=open("/dev/fb0",O_RDWR);
    if(fd<0)
    
        perror("设备文件打开失败");
        return 0;
    

    /*1. 获取LCD屏的可变形参*/
    ioctl(fd,FBIOGET_VSCREENINFO,&var);
    printf("分辨率:%d*%d\\n",var.xres,var.yres);
    printf("像素点位数:%d\\n",var.bits_per_pixel);

    /*2. 获取LCD屏的固定形参*/
    ioctl(fd,FBIOGET_FSCREENINFO,&fix);
    printf("映射的长度:%d\\n",fix.smem_len);
    printf("一行的字节数:%d\\n",fix.line_length);

    /*3. 映射LCD缓冲区地址到进程空间*/
    fb_mem=mmap(NULL,fix.smem_len,PROT_READ|PROT_WRITE,MAP_SHARED,fd,0);
    if(fb_mem==NULL)
    
        perror("空间映射失败!\\n");
        return 0;
    

    /*4. 控制显示屏*/
    memset(fb_mem,0xFFFFFF,fix.smem_len); //将屏幕清屏为白色

    ShowFont(100+0*56,100,56,font);
    ShowFont(100+1*56,100,56,font+7*56*1);
    ShowFont(100+2*56,100,56,font+7*56*2);

    munmap(fb_mem,fix.smem_len);
    close(fd);
    return 0;


unsigned char font[]=
 
/*--  文字:  嵌  --*/
/*--  幼圆42;  此字体下对应的点阵为:宽x高=56x56   --*/
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x38,
0x00,0x00,0x00,0x03,0x80,0x00,0x7C,0x00,0x03,0x80,0x07,0xC0,0x00,0x7C,0x00,0x03,
0xC0,0x07,0xC0,0x00,0x7C,0x00,0x03,0xC0,0x07,0xC0,0x00,0x7C,0x00,0x03,0xC0,0x07,
0xC0,0x00,0x7C,0x00,0x03,0xC0,0x07,0xC0,0x00,0x7C,0x00,0x03,0xC0,0x07,0xC0,0x00,
0x7C,0x00,0x03,0xC0,0x07,0xFF,0xFF,0xFF,0xFF,0xFF,0xC0,0x03,0xFF,0xFF,0xFF,0xFF,
0xFF,0x80,0x01,0xFF,0xFF,0xFF,0xFF,0xFF,0x80,0x00,0xFF,0xFF,0xFF,0xFF,0xFC,0x00,
0x00,0x00,0x00,0x00,0x60,0x00,0x00,0x00,0xE0,0x07,0x00,0xF0,0x00,0x00,0x01,0xE0,
0x0F,0x01,0xF0,0x00,0x00,0x01,0xE0,0x0F,0x01,0xF0,0x00,0x00,0x01,0xE0,0x0F,0x01,
0xE0,0x00,0x00,0x01,0xE0,0x0F,0x01,0xE0,0x00,0x00,0x1F,0xFF,0xFF,0xF3,0xFF,0xFF,
0xF0,0x3F,0xFF,0xFF,0xFB,0xFF,0xFF,0xF8,0x3F,0xFF,0xFF,0xFB,0xFF,0xFF,0xF8,0x1F,
0xFF,0xFF,0xE7,0xC3,0x80,0x7C,0x01,0xE0,0x0F,0x07,0x87,0x80,0x7C,0x01,0xE0,0x0F,
0x0F,0x87,0x80,0x7C,0x01,0xE0,0x0F,0x0F,0x87,0x80,0x78,0x01,0xE0,0x0F,0x1F,0x07,
0x80,0x78,0x01,0xE0,0x0F,0x1F,0x07,0x80,0xF8,0x01,0xE0,0x0F,0x3E,0x07,0x80,0xF8,
0x01,0xE0,0x0F,0x3E,0x07,0x80,0xF0,0x01,0xE0,0x0F,0x3C,0x07,0x81,0xF0,0x01,0xE0,
0x0F,0x3C,0x07,0x81,0xE0,0x01,0xE0,0x0F,0x00,0x07,0x83,0xE0,0x01,0xFF,0xFF,0x00,
0x07,0xC3,0xC0,0x01,0xFF,0xFF,0x00,0x07,0xC0,0x00,0x01,0xFF,0xFF,0x00,0x0F,0xE0,
0x00,0x01,0xFF,0xFF,0x00,0x0F,0xE0,0x00,0x01,0xE0,0x0F,0x00,0x0F,0xF0,0x00,0x01,
0xE0,0x0F,0x00,0x1E,0xF0,0x00,0x01,0xE0,0x0F,0x00,0x1E,0xF8,0x00,0x01,0xE0,0x0F,
0x00,0x3E,0x78,0x00,0x01,0xE0,0x0F,0x00,0x7C,0x7C,0x00,0x01,0xE0,0x0F,0x00,0x78,
0x3E,0x00,0x01,0xE0,0x0F,0x00,0xF8,0x1E,0x00,0x01,0xE0,0x0F,0x01,0xF0,0x1F,0x00,
0x01,0xE0,0x0F,0x03,0xE0,0x0F,0x80,0x01,0xE0,0x0F,0x07,0xE0,0x07,0xC0,0x01,0xE0,
0x0F,0x0F,0xC0,0x03,0xE0,0x01,0xE0,0x0F,0x1F,0x80,0x01,0xF0,0x01,0xFF,0xFF,0x3F,
0x00,0x01,0xF8,0x00,0xFF,0xFF,0x7E,0x00,0x00,0xFC,0x00,0x7F,0xFE,0x78,0x00,0x00,
0x3C,0x00,0x00,0x00,0x70,0x00,0x00,0x18,

/*--  文字:  入  --*/
/*--  幼圆42;  此字体下对应的点阵为:宽x高=56x56   --*/
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x0F,0x00,0x00,0x00,0x00,0x00,0x00,0x1F,0xC0,0x00,0x00,
0x00,0x00,0x00,0x0F,0xE0,0x00,0x00,0x00,0x00,0x00,0x07,0xF0,0x00,0x00,0x00,0x00,
0x00,0x01,0xF8,0x00,0x00,0x00,0x00,0x00,0x00,0xFC,0x00,0x00,0x00,0x00,0x00,0x00,
0x7C,0x00,0x00,0x00,0x00,0x00,0x00,0x3E,0x00,0x00,0x00,0x00,0x00,0x00,0x1F,0x00,
0x00,0x00,0x00,0x00,0x00,0x1F,0x00,0x00,0x00,0x00,0x00,0x00,0x3F,0x00,0x00,0x00,
0x00,0x00,0x00,0x3F,0x80,0x00,0x00,0x00,0x00,0x00,0x3F,0x80,0x00,0x00,0x00,0x00,
0x00,0x7F,0xC0,0x00,0x00,0x00,0x00,0x00,0x7F,0xC0,0x00,0x00,0x00,0x00,0x00,0x7B,
0xC0,0x00,0x00,0x00,0x00,0x00,0xFB,0xE0,0x00,0x00,0x00,0x00,0x00,0xF1,0xE0,0x00,
0x00,0x00,0x00,0x00,0xF1,0xE0,0x00,0x00,0x00,0x00,0x01,0xF1,0xF0,0x00,0x00,0x00,
0x00,0x01,0xE0,0xF0,0x00,0x00,0x00,0x00,0x03,0xE0,0xF8,0x00,0x00,0x00,0x00,0x03,
0xC0,0xF8,0x00,0x00,0x00,0x00,0x07,0xC0,0x7C,0x00,0x00,0x00,0x00,0x07,0x80,0x7C,
0x00,0x00,0x00,0x00,0x0F,0x80,0x3C,0x00,0x00,0x00,0x00,0x0F,0x00,0x3E,0x00,0x00,
0x00,0x00,0x1F,0x00,0x1E,0x00,0x00,0x00,0x00,0x1E,0x00,0x1F,0x00,0x00,0x00,0x00,
0x3E,0x00,0x0F,0x00,0x00,0x00,0x00,0x7C,0x00,0x0F,0x80,0x00,0x00,0x00,0x7C,0x00,
0x07,0xC0,0x00,0x00,0x00,0xF8,0x00,0x07,0xC0,0x00,0x00,0x01,0xF0,0x00,0x03,0xE0,
0x00,0x00,0x01,0xE0,0x00,0x01,0xE0,0x00,0x00,0x03,0xE0,0x00,0x01,0xF0,0x00,0x00,
0x07,0xC0,0x00,0x00,0xF8,0x00,0x00,0x0F,0x80,0x00,0x00,0xF8,0x00,0x00,0x1F,0x00,
0x00,0x00,0x7C,0x00,0x00,0x1F,0x00,0x00,0x00,0x3E,0x00,0x00,0x3E,0x00,0x00,0x00,
0x3E,0x00,0x00,0x7C,0x00,0x00,0x00,0x1F,0x00,0x00,0xF8,0x00,0x00,0x00,0x0F,0x80,
0x01,0xF0,0x00,0x00,0x00,0x07,0xC0,0x03,0xE0,0x00,0x00,0x00,0x03,0xE0,0x07,0xC0,
0x00,0x00,0x00,0x03,0xF0,0x0F,0x80,0x00,0x00,0x00,0x01,0xF8,0x1F,0x00,0x00,0x00,
0x00,0x00,0xFC,0x1E,0x00,0x00,0x00,0x00,0x00,0x7C,0x1C,0x00,0x00,0x00,0x00,0x00,
0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,

/*--  文字:  式  --*/
/*--  幼圆42;  此字体下对应的点阵为:宽x高=56x56   --*/
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x06,0x00,0x00,0x00,0x00,0x00,0x00,0xEF,0x80,0x00,0x00,0x00,0x00,0x01,0xEF,0xE0,
0x00,0x00,0x00,0x00,0x01,0xEF,0xF0,0x00,0x00,0x00,0x00,0x01,0xE3,0xFC,0x00,0x00,
0x00,0x00,0x01,0xE0,0xFF,0x00,0x00,0x00,0x00,0x01,0xF0,0x7F,0x80,0x00,0x00,0x00,
0x01,0xF0,0x1F,0xC0,0x00,0x00,0x00,0x00,0xF0,0x07,0xC0,0x00,0x00,0x00,0x00,0xF0,
0x03,0xC0,0x0F,0xFF,0xFF,0xFF,0xFF,0xFF,0xF0,0x1F,0xFF,0xFF,0xFF,0xFF,0xFF,0xF8,
0x1F,0xFF,0xFF,0xFF,0xFF,0xFF,0xF8,0x0F,0xFF,0xFF,0xFF,0xFF,0xFF,0xF0,0x00,0x00,
0x00,0x00,0xF0,0x00,0x00,0x00,0x00,0x00,0x00,0xF8,0x00,0x00,0x00,0x00,0x00,0x00,
0x78,0x00,0x00,0x00,0x00,0x00,0x00,0x78,0x00,0x00,0x00,0x00,0x00,0x00,0x78,0x00,
0x00,0x00,0x00,0x00,0x00,0x78,0x00,0x00,0x00,0x00,0x00,0x00,0x78,0x00,0x00,0x00,
0x00,0x00,0x00,0x7C,0x00,0x00,0x0F,0xFF,0xFF,0xFE,0x3C,0x00,0x00,0x0F,0xFF,0xFF,
0xFE,0x3C,0x00,0x00,0x0F,0xFF,0xFF,0xFE,0x3C,0x00,0x00,0x00,0x00,0xF0,0x00,0x3C,
0x00,0x00,0x00,0x00,0xF0,0x00,0x3E,0x00,0x00,0x00,0x00,0xF0,0x00,0x3E,0x00,0x00,
0x00,0x00,0xF0,0x00,0x1E,0x00,0x00,0x00,0x00,0xF0,0x00,0x1E,0x00,0x00,0x00,0x00,
0xF0,0x00,0x1E,0x00,0x00,0x00,0x00,0xF0,0x00,0x1F,0x00,0x00,0x00,0x00,0xF0,0x00,
0x0F,0x00,0x00,0x00,0x00,0xF0,0x00,0x0F,0x00,0x00,0x00,0x00,0xF0,0x00,0x0F,0x80,
0x00,0x00,0x00,0xF0,0x00,0x0F,0x80,0x18,0x00,0x00,0xF0,0x00,0x07,0x80,0x3C,0x00,
0x00,0xF0,0x00,0x07,0x80,0x3C,0x00,0x00,0xF0,0x00,0x07,0xC0,0x3C,0x00,0x00,0xF0,
0x00,0x03,0xC0,0x3C,0x00,0x00,0xF0,0x03,0xC3,0xE0,0x3C,0x00,0x00,0xF0,0x1F,0xC1,
0xE0,0x3C,0x00,0x00,0xF1,0xFF,0xC1,0xF0,0x3C,0x00,0x00,0xFF,0xFF,0x01,0xF0,0x3C,
0x00,0x01,0xFF,0xF8,0x00,0xF8,0x3C,0x00,0x0F,0xFF,0x80,0x00,0xF8,0x7C,0x01,0xFF,
0xFC,0x00,0x00,0x7C,0x7C,0x1F,0xFF,0xC0,0x00,0x00,0x3F,0x78,0x3F,0xFC,0x00,0x00,
0x00,0x1F,0xF8,0x3F,0xC0,0x00,0x00,0x00,0x1F,0xF0,0x00,0x00,0x00,0x00,0x00,0x07,
0xF0,0x00,0x00,0x00,0x00,0x00,0x01,0xE0
;

3.2 调用字库显示

单个汉字取模太麻烦,可以使用点阵字库取模软件,然后程序里打开字库,读取字模进行绘制,下面的示例代码就是采用字库读取字模完成汉字显示。

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/fb.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>

struct fb_var_screeninfo var;   //可变参数
struct fb_fix_screeninfo fix;   //固定参数
unsigned char *fb_mem=NULL;     //LCD屏的首地址
unsigned char *fb_GBK=NULL;     //GBK字库的首地址
extern unsigned char font[];
extern const unsigned char ASCII_16_32[95][64];

/*
函数功能: 画点
*/
void Show_Pixel(int x,int y,int color)

    unsigned int *lcd=(unsigned int *)(fb_mem+y*var.xres*var.bits_per_pixel/8+x*var.bits_per_pixel/8);
    *lcd=color; //颜色赋值


/*
函数功能: 显示中文
说明:  取模的字体是按照横向取模进行取点阵码。
       取模的字体宽度是8的倍数。
*/
void ShowFont(int x,int y,int size,unsigned char *font)

    unsigned char L,H;
    unsigned int Addr;
    unsigned int font_size=size*size/8; //得到该字节的总字节大小
    unsigned char FontData[128];          //最大可以存放32*32尺寸字体点阵码
    unsigned char *GBK_p; //存放汉字点阵码首地址
    /*计算该汉字在字库里的地址偏移量*/
    L=*(font+1); //低字节
    H=*font;     //高字节
    if(L<0x7f)L=L-0x40;
    else L=L-0x41;
    H=H-0x81;
    Addr=(190*H+L)*font_size; //得到当前汉字在字库里的偏移量
    GBK_p=(unsigned char *)(Addr+fb_GBK); //得到汉字点阵码在字库里首地址

    int i,j,x0=x;
    unsigned char tmp;
    for(i=0;i<size/8*size;i++)
    
        tmp=GBK_p[i];
        for(j=0;j<8;j++)
        
            if(tmp&0x80)Show_Pixel(x0,y,0xFF0033);
            //else 画背景色
            x0++;
            tmp<<=1;
        
        if(x0-x==size)
        
            y++;
            x0=x;
        
    


/*
函数功能:  显示一个ASCII码。“空格开始 到  ~ 结束”
 !"#$%&()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz|~

说明: ASCII码取模 宽度和高度必须是8的倍数,传入的size(高)
 */
void ShowASCII(int x,int y,int size,unsigned char c_data)

    int i,j,x0=x;
    unsigned char data;
    int cnt;
    if(c_data<  ||  c_data > ~)return; 
    cnt=c_data- ;
    for(i=0;i<size/2/8*size;i++)
    
         switch(size)
         
            case 16:
                break;
             case 32:
                data=ASCII_16_32[cnt][i];
                break;
         
         for(j=0;j<8;j++)
         
             if(data&0x80)Show_Pixel(x0,y,0xFF0033);
             x0++;
             data<<=1;
         
         if(x0-x==size/2)
         
             x0=x;
             y++;
         
    


int main(int argc,char **argv)

    if(argc!=2)
    
        printf("./app <GBK字库文件>\\n");
        return 0;
    

    int fd=open("/dev/fb0",O_RDWR);
    if(fd<0)
    
        perror("设备文件打开失败");
        return 0;
    

    /*1. 获取LCD屏的可变形参*/
    ioctl(fd,FBIOGET_VSCREENINFO,&var);
    printf("分辨率:%d*%d\\n",var.xres,var.yres);
    printf("像素点位数:%d\\n",var.bits_per_pixel);

    /*2. 获取LCD屏的固定形参*/
    ioctl(fd,FBIOGET_FSCREENINFO,&fix);
    printf("映射的长度:%d\\n",fix.smem_len);
    printf("一行的字节数:%d\\n",fix.line_length);

    /*3. 映射LCD缓冲区地址到进程空间*/
    fb_mem=mmap(NULL,fix.smem_len,PROT_READ|PROT_WRITE,MAP_SHARED,fd,0);
    if(fb_mem==NULL)
    
        perror("空间映射失败!\\n");
        return 0;
    

    /*4. 映射GBK字库文件到进程空间*/
    int gbk_fb;
    struct stat gbk_buf;
    gbk_fb=open(argv[1],2);
    if(gbk_fb<0)
    
        perror("GBK字库文件打开失败!");
        return 0;
    
    stat(argv[1],&gbk_buf);
    printf("GBK字库文件大小=%d\\n",gbk_buf.st_size);
    fb_GBK=mmap(NULL,gbk_buf.st_size,PROT_READ,MAP_SHARED,gbk_fb,0);
    if(fb_GBK==NULL)
    
        perror("空间映射失败!\\n");
        return 0;
    

    /*4. 控制显示屏*/
    memset(fb_mem,0xFFFFFF,fix.smem_len); //将屏幕清屏为白色

    ShowFont(100+0*32,100,32,"嵌");
    ShowFont(100+1*32,100,32,"入");
    ShowFont(100+2*32,100,32,"式");
    ShowFont(100+3*32,100,32,"开");
    ShowFont(100+4*32,100,32,"发");

    ShowASCII(100+0*16,200,32,A);
    ShowASCII(100+1*16,200,32,C);
    ShowASCII(100+2*16,200,32,B);

    munmap(fb_mem,fix.smem_len);
    close(fd);
    return 0;

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