程序很简单，就是进行内存映射之后写frambuffer。这个程序是在华清远见的一个程序上改的，目前只支持16BPP的液晶屏。代码如下：
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <linux/fb.h>
#include <sys/mman.h>
int main(int argc, char *argv[])
{
int fbfd = 0;
struct fb_var_screeninfo vinfo;
unsigned long screensize = 0;
unsigned long location = 0;
char *fbp = 0;
int x = 0, y = 0;
int seg_len = 0;
int tmp_seg_len = 0;
int seg_num = 0;
unsigned short rgb = 0;
unsigned int r = 0, g = 0, b = 0;
// Open the file for reading and writing
fbfd = open("/dev/fb0", O_RDWR);
if (!fbfd) {
printf("Error: cannot open framebuffer device.\n");
exit(1);
}
printf("The framebuffer device was opened successfully.\n");
// Get variable screen information
if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo)) {
printf("Error reading variable information.\n");
exit(1);
}
printf("%dx%d, %dbpp\n", vinfo.xres, vinfo.yres, vinfo.bits_per_pixel);
if (vinfo.bits_per_pixel != 16) {
printf("Error: not supported bits_per_pixel, it only supports 16 bit color\n");
exit(1);
}
// Figure out the size of the screen in bytes
screensize = vinfo.xres * vinfo.yres * 2;
// Map the device to memory
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.\n");
exit(4);
}
printf("The framebuffer device was mapped to memory successfully.\n");
seg_len = vinfo.yres/6;
#if 1
seg_len = vinfo.yres/6;
for (seg_num = 0; seg_num < 6; seg_num++) {
if (seg_num == 5)
tmp_seg_len = vinfo.yres - seg_len*5;
else
tmp_seg_len = seg_len;
for (y = 0; y < tmp_seg_len; y++) {
for (x = 0; x < vinfo.xres; x++) {
location = seg_num*seg_len*vinfo.xres*2 + (y*vinfo.xres+ x)*2;
switch (seg_num) {
case 0:
r = 0xff;
g = (0xff/seg_len)*y;
b = 0;
break;
case 1:
r = (0xff/seg_len)*(seg_len-y);
g = 0xff;
b = 0;
break;
case 2:
r = 0;
g = 0xff;
b = (0xff/seg_len)*y;
break;
case 3:
r = 0;
g = (0xff/seg_len)*(seg_len-y);
b = 0xff;
break;
case 4:
r = (0xff/seg_len)*y;
g = 0;
b = 0xff;
break;
case 5:
r = 0xff;
b = (0xff/seg_len)*(seg_len-y);
g = 0;
break;
default:
printf("%s--%d:unknown seg_num %d\n", __FILE__, __LINE__);
break;
}
r = (r*0x1f)/0xff;
g = (g*0x3f)/0xff;
b = (b*0x1f)/0xff;
rgb = (r << 11) | (g << 5) | b;
*((unsigned short*)(fbp + location)) = rgb;
}
}
}
sleep(2);
seg_len = vinfo.yres/6;
for (seg_num = 0; seg_num < 6; seg_num++) {
if (seg_num == 5)
tmp_seg_len = vinfo.yres - seg_len*5;
else
tmp_seg_len = seg_len;
for (y = 0; y < tmp_seg_len; y++) {
for (x = 0; x < vinfo.xres; x++) {
location = seg_num*seg_len*vinfo.xres*2 + (y*vinfo.xres+ x)*2;
switch (seg_num) {
case 0://grey
r = 100;
g = 100;
b = 100;
break;
case 1: //black
r = 0x00;
g = 0x00;
b = 0x00;
break;
case 2://white
r = 0xff;
g = 0xff;
b = 0xff;
break;
case 3://red
r = 0xff;
g = 0;
b = 0;
break;
case 4: //green
r = 0;
g = 0xff;
b = 0;
break;
case 5: //blue
r = 0;
g = 0;
b = 0xff;
break;
default:
printf("%s--%d:unknown seg_num %d\n", __FILE__, __LINE__);
break;
}
r = (r*0x1f)/0xff;
g = (g*0x3f)/0xff;
b = (b*0x1f)/0xff;
rgb = (r << 11) | (g << 5) | b;
*((unsigned short*)(fbp + location)) = rgb;
}
}
}
#endif
#if 1
sleep(2);
seg_len = vinfo.xres/6;
for (seg_num = 0; seg_num < 6; seg_num++) {
if (seg_num == 5)
tmp_seg_len = vinfo.xres - seg_len*5;
else
tmp_seg_len = seg_len;
for (x = 0; x < tmp_seg_len; x++) {
for (y = 0; y < vinfo.yres; y++) {
location = y*vinfo.xres*2 + (seg_num*seg_len + x)*2;
switch (seg_num) {
case 0:
r = 0xff;
g = (0xff/seg_len)*x;
b = 0;
break;
case 1:
r = (0xff/seg_len)*(seg_len-x);
g = 0xff;
b = 0;
break;
case 2:
r = 0;
g = 0xff;
b = (0xff/seg_len)*x;
break;
case 3:
r = 0;
g = (0xff/seg_len)*(seg_len-x);
b = 0xff;
break;
case 4:
r = (0xff/seg_len)*x;
g = 0;
b = 0xff;
break;
case 5:
r = 0xff;
g = 0;
b = (0xff/seg_len)*(seg_len-x);
break;
default:
printf("%s--%d:unknown seg_num %d\n", __FILE__, __LINE__);
break;
}
r = (r*0x1f)/0xff;
g = (g*0x3f)/0xff;
b = (b*0x1f)/0xff;
rgb = (r << 11) | (g << 5) | b;
*((unsigned short*)(fbp + location)) = rgb;
}
}
}
sleep(2);
seg_len = vinfo.xres/6;
/* white black gray red green blue */
for (seg_num = 0; seg_num < 6; seg_num++) {
if (seg_num == 5)
tmp_seg_len = vinfo.xres - seg_len*5;
else
tmp_seg_len = seg_len;
for (x = 0; x < tmp_seg_len; x++) {
for (y = 0; y < vinfo.yres; y++) {
location = y*vinfo.xres*2 + (seg_num*seg_len + x)*2;
switch (seg_num) {
case 0://grey
r = 100;
g = 100;
b = 100;
break;
case 1://black
r = 0;
g = 0;
b = 0;
break;
case 2: //white
r = 0xff;
g = 0xff;
b = 0xff;
break;
case 3://red
r = 0xff;
g = 0;
b = 0;
break;
case 4: //green
r = 0;
g = 0xff;
b = 0;
break;
case 5: //blue
r = 0;
g = 0;
b = 0xff;
break;
default:
printf("%s--%d:unknown seg_num %d\n", __FILE__, __LINE__);
break;
}
r = (r*0x1f)/0xff;
g = (g*0x3f)/0xff;
b = (b*0x1f)/0xff;
rgb = (r << 11) | (g << 5) | b;
*((unsigned short*)(fbp + location)) = rgb;
}
}
}
#endif
munmap(fbp, screensize);
close(fbfd);
return 0;
}