嵌入式Linux下完成LCD屏文字显示(帧缓冲框架)

一身转战三千里，一剑曾当百万师。这篇文章主要讲述嵌入式Linux下完成LCD屏文字显示(帧缓冲框架)相关的知识，希望能为你提供帮助。
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。

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2. 编程思路下面是帧缓冲框架图：

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【嵌入式Linux下完成LCD屏文字显示(帧缓冲框架)】

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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。

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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=https://www.songbingjia.com/android/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=https://www.songbingjia.com/android/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;