Arm Linux LCD应用程序 For Mini2440

应用程序实现//mini2440实现 #include <unistd.h>
#include <stdlib.h>#include <fcntl.h>
#include <linux/fb.h>
#include <sys/mman.h>
int main（）
{
    int fbfd = 0;
    struct fb_var_screeninfo vinfo;
    struct fb_fix_screeninfo finfo;
    long int screensize = 0;
    char *fbp = 0;
    int x = 0, y = 0;
    long int location = 0;    // Open the file for reading and writing     fbfd = open（"/dev/fb0", O_RDWR）;
    if （！fbfd） {
        printf（"Error: cannot open framebuffer device. "）;
        exit（1）;
    }
    printf（"The framebuffer device was opened successfully. "）;    // Get fixed screen information    //FBIOGET_FSCREENINFO获得固定的屏幕参数设置    if （ioctl（fbfd, FBIOGET_FSCREENINFO, &finfo）） {
        printf（"Error reading fixed information. "）;
        exit（2）;
    }    printf（"%d, %d, %d, %d ", finfo.smem_start, finfo.smem_len, finfo.mmio_start,finfo.mmio_len）;
    //869007360, 153600, 0, 0    // Get variable screen information    //FBIOGET_VSCREENINFO 获得可变的屏幕参数    if （ioctl（fbfd, FBIOGET_VSCREENINFO, &vinfo）） {
        printf（"Error reading variable information. "）;
        exit（3）;
    }    printf（"%dx%d, %dbpp ", vinfo.xres, vinfo.yres, vinfo.bits_per_pixel）;
    //320X240,16bpp bpp 每像素位数每个点用多少个字节表示
    // Figure out the size of the screen in bytes     screensize = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;
    //2^16=64K TFT 320*240*16/8=153600byte
    // Map the device to memory    /*void *mmap（void *start, size_t length, int prot, int flags,
int fd, off_t offset）;mmap函数是unix/linux下的系统调用
     fbmem.c是内核的，应用程序调用了mmap进入内核空间就是执行的fb_mmap了，
     应用程序是统一的接口，但是在内核空间，不同的驱动使用的实现函数是不一样的*/
    //#include <unistd.h> and #include <sys/mman.h> /usr/include/sys/mman.h     fbp = （char *）mmap（0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED,
                        fbfd, 0）;
    if （（int）fbp == -1） {
        printf（"Error: failed to map framebuffer device to memory. "）;
        exit（4）;
    }
    printf（"The framebuffer device was mapped to memory successfully. "）;
#if 1
     x = 10; y = 10; // Where we are going to put the pixel
    // Figure out where in memory to put the pixel    for （y = 10; y < 20; y++）
        for （x = 10; x < 30; x++）
        {
             location = （x+vinfo.xoffset） * （vinfo.bits_per_pixel/8） +
                       （y+vinfo.yoffset） * finfo.line_length;            if （vinfo.bits_per_pixel == 32）
            {
                *（fbp + location） = 10; // Some blue                *（fbp + location + 1） = 15+（x-10）/2; // A little green                *（fbp + location + 2） = 20-（y-10）/5; // A lot of red                *（fbp + location + 3） = 0; // No transparency            }
            else
            { //assume 16bpp                unsigned short b = 10;
                unsigned short g = （x-10）/6; // A little green                unsigned short r = 31-（y-10）/16; // A lot of red                unsigned short t = r<<11 | g << 5 | b;
                *（（unsigned short *）（fbp + location）） = t;
    //     printf（"x=%d,%d ",x,y）;            }
        }
#endif
     munmap（fbp, screensize）;//删除特定地址区域的对象映射 int munmap（void *start, size_t length）;     printf（"The framebuffer device was munmapped to memory successfully. "）;
    close（fbfd）;
    printf（"The framebuffer device was closed successfully. "）;
    return 0;
}