使用交叉编译工具，编译后，用nfs传到开发板直接运行，可在最小系统下运行，自适应RGB565,RBG888，16位，24位，32位。
代码如下：
/* 在LCD上显示单色 */
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <linux/fb.h>
#include <sys/mman.h>
#define RED_COLOR565 0xf800
#define GREEN_COLOR565 0x07e0
#define BLUE_COLOR565 0x001f
#define RED_COLOR888_32bpp 0x00ff0000
#define GREEN_COLOR888_32bpp 0x0000ff00
#define BLUE_COLOR888_32bpp 0x000000ff
#define RGB888_RED 0x00ff0000
#define RGB888_GREEN 0x0000ff00
#define RGB888_BULE 0x000000ff
#define RGB565_RED 0xf800
#define RGB565_GREEN 0x07e0
#define RGB565_BLUE 0x001f
static unsigned short RGB8888ToRGB565(unsigned int n888Color)
{
unsigned short n565Color = 0;
unsigned char cRed, cGreen, cBlue;
cRed = (n888Color & RGB888_RED) >> 19;
cGreen = (n888Color & RGB888_GREEN) >> 10;
cBlue = (n888Color & RGB888_BULE) >> 3;
n565Color = (cRed << 11) + (cGreen << 5) + (cBlue << 0);
return n565Color;
}
static unsigned int RGB565ToRGB888(unsigned short n565Color)
{
unsigned int n888Color = 0;
unsigned char cRed, cGreen, cBlue;
cRed = (n565Color & RGB565_RED) >> 8;
cGreen = (n565Color & RGB565_GREEN) >> 3;
cBlue = (n565Color & RGB565_BLUE) << 3;
n888Color = (cRed << 16) + (cGreen << 8) + (cBlue << 0);
return n888Color;
}
int main(void)
{
int fd_fb = 0;
struct fb_var_screeninfo vinfo;
struct fb_fix_screeninfo finfo;
long int screen_size = 0;
int *fbp565 = NULL;
unsigned int RED_COLOR888, GREEN_COLOR888, BLUE_COLOR888;
int x = 0, y = 0;
fd_fb = open("/dev/fb0", O_RDWR);
if(!fd_fb)
{
printf("Error:cannot open framebuffer device.\n");
return -1;
}
/* Get fixed screen info */
if(ioctl(fd_fb, FBIOGET_FSCREENINFO, &finfo))
{
printf("Error reading fixed information.\n");
return -2;
}
/* Get variable screen info */
if(ioctl(fd_fb, FBIOGET_VSCREENINFO, &vinfo))
{
printf("Error reading variable information.\n");
return -3;
}
screen_size = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;
printf("screen_size = %d, vinfo.xres = %d, vinfo.yres = %d, vinfo.bits_per_pixel = %d\n", screen_size, vinfo.xres, vinfo.yres, vinfo.bits_per_pixel);
/* map framebuffer to user memory */
fbp565 = (int *)mmap(0, screen_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd_fb, 0);
if((int)fbp565 == -1)
{
printf("Error: failed to map framebuffer device to memory.\n");
return -4;
}
if(vinfo.bits_per_pixel == 16)
{
printf("16 bpp framebuffer\n");
//Red Screen
printf("Red Screen\n");
for(y = 0; y < vinfo.yres / 3; y++)
{
for(x = 0; x < vinfo.xres; x++)
{
*(fbp565 + y * vinfo.xres + x) = RED_COLOR565;
}
}
//Green Screen
printf("Green Screen\n");
for(y = vinfo.yres / 3; y < (vinfo.yres * 2) / 3; y++)
{
for(x = 0; x < vinfo.xres; x++)
{
*(fbp565 + y * vinfo.xres + x) = GREEN_COLOR565;
}
}
//Blue Screen
printf("Blue Screen\n");
for(y = (vinfo.yres * 2) / 3; y < vinfo.yres; y++)
{
for(x = 0; x < vinfo.xres; x++)
{
*(fbp565 + y * vinfo.xres + x) = BLUE_COLOR565;
}
}
}
else if(vinfo.bits_per_pixel == 24)
{
RED_COLOR888 = RGB565ToRGB888(RED_COLOR565);
GREEN_COLOR888 = RGB565ToRGB888(GREEN_COLOR565);
BLUE_COLOR888 = RGB565ToRGB888(BLUE_COLOR565);
printf("24 bpp framebuffer\n");
//Red Screen
printf("Red Screen\n");
for(y = 0; y < vinfo.yres / 3; y++)
{
for(x = 0; x < vinfo.xres; x++)
{
*(fbp565 + y * vinfo.xres + x) = RED_COLOR888;
}
}
//Green Screen
printf("Green Screen\n");
for(y = vinfo.yres / 3; y < (vinfo.yres * 2) / 3; y++)
{
for(x = 0; x < vinfo.xres; x++)
{
*(fbp565 + y * vinfo.xres + x) = GREEN_COLOR888;
}
}
//Blue Screen
printf("Blue Screen\n");
for(y = (vinfo.yres * 2) / 3; y < vinfo.yres; y++)
{
for(x = 0; x < vinfo.xres; x++)
{
*(fbp565 + y * vinfo.xres + x) = BLUE_COLOR888;
}
}
}
else if(vinfo.bits_per_pixel == 32)
{
printf("32 bpp framebuffer\n");
//Red Screen
printf("Red Screen\n");
for(y = 0; y < vinfo.yres / 3; y++)
{
for(x = 0; x < vinfo.xres; x++)
{
*(fbp565 + y * vinfo.xres + x) = RED_COLOR888_32bpp;
}
}
//Green Screen
printf("Green Screen\n");
for(y = vinfo.yres / 3; y < (vinfo.yres * 2) / 3; y++)
{
for(x = 0; x < vinfo.xres; x++)
{
*(fbp565 + y * vinfo.xres + x) = GREEN_COLOR888_32bpp;
}
}
//Blue Screen
printf("Blue Screen\n");
for(y = (vinfo.yres * 2) / 3; y < vinfo.yres; y++)
{
for(x = 0; x < vinfo.xres; x++)
{
*(fbp565 + y * vinfo.xres + x) = BLUE_COLOR888_32bpp;
}
}
}
else
{
printf("Warnning: bpp is not 16 and 24 and 32\n");
}
munmap(fbp565, screen_size);
close(fd_fb);
return 0;
}