本来今天是要结合udp的例子传输数据的，但是被一个数学逻辑搞了半天，记录一下避坑吧。

代码

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

uint32_t fb_line,fb_byte_per,fb_all_bit;
unsigned char *fb_base;
static struct fb_var_screeninfo var;

void lcd_flash(unsigned int  x,unsigned int y,int endx,int endy,unsigned int *buffer,unsigned int size)
{
    unsigned int i;
    unsigned int *fb_test=(unsigned int *)fb_base;
    fb_test+=x+fb_line*y/4;//fb_line*0/4;//
    for(i=0;i<size;i++)
    {
        *fb_test = buffer[i];
        if(!((i+1)%(endx+1))&&(i!=0)){
            fb_test+=(fb_line/4-endx);//800-239;//
        }
        else{
            fb_test++;
        }
        // if(i==239*2)
        // break;
       
    }
}

int main()
{
    unsigned int buf[240*240];
    int fb_handle;
    fb_handle = open("/dev/fb0",O_RDWR);
    if(fb_handle < 0)
    {
        return -1;
    }
    memset(buf,-1,sizeof(buf));
    if(ioctl(fb_handle,FBIOGET_VSCREENINFO,&var))//使用获取动态数据的标志符从驱动获取屏幕数据
    {
        return -1;
    }
    ////////获取屏幕的数据
    fb_line = var.xres * var.bits_per_pixel / 8;//长度
    fb_byte_per = var.bits_per_pixel / 8;
    fb_all_bit = var.xres * var.yres * var.bits_per_pixel / 8;//总贞数
    ////////对文件进行映射
    fb_base = (unsigned char *)mmap(NULL , fb_all_bit, PROT_READ | PROT_WRITE, MAP_SHARED, fb_handle, 0);
    if(fb_base == (unsigned char *)-1)
    {
        printf("failed to mmap");
        return -1;
    }
    printf("bpp is %d\r\n all is %d\r\n x is %d y is %d\r\n",var.bits_per_pixel,var.xres*var.yres,var.xres,var.yres);
    lcd_flash(10,0,239,239,buf,240*240);
    //memset(fb_base, 0xf0, fb_all_bit);//清个白屏试试

}