昨天做的一個極簡單的framebuffer的例子，用來學習怎樣操作fb設備。
這段代碼是在picogl的vesafb backend部分的基礎上簡出來的，所以變量名還保留着。
流程如下：
１ 打開framebuffer設備；
２ 通過ioctl取得fixed screen information；
３ 通過ioctl取得variable screen information；
４ 通過mmap映射設備內存到進程空間；
５ 寫framebuffer；
６ 終止。
#include
#include
#include
#include
#include
#include
struct fb_fix_screeninfo FixedInfo;
struct fb_var_screeninfo OrigVarInfo;
static int FrameBufferFD = -1;
void *FrameBuffer = ( void *) -1;
void openFBDEV( void ) {
/* open the framebuffer device */
FrameBufferFD = open( "/dev/fb0" , O_RDWR);
if (FrameBufferFD < 0) {
fprintf(stderr, "Error opening /dev/fb0/n" );
exit(1);
}
/* Get the fixed screen info */
if (ioctl(FrameBufferFD, FBIOGET_FSCREENINFO, &FixedInfo)) {
fprintf(stderr, "error: ioctl(FBIOGET_FSCREENINFO) failed/n" );
exit(1);
}
/* get the variable screen info */
if (ioctl(FrameBufferFD, FBIOGET_VSCREENINFO, &OrigVarInfo)) {
fprintf(stderr, "error: ioctl(FBIOGET_VSCREENINFO) failed/n" );
exit(1);
}
if (FixedInfo.visual != FB_VISUAL_TRUECOLOR && FixedInfo.visual != FB_VISUAL_DIRECTCOLOR) {
fprintf(stderr, "non-TRUE/DIRECT-COLOR visuals (0x%x) not supported by this demo./n" , FixedInfo.visual);
exit(1);
}
/*
* fbdev says the frame buffer is at offset zero, and the mmio region
* is immediately after.
*/
/* mmap the framebuffer into our address space */
FrameBuffer = ( void *) mmap(0, /* start */
FixedInfo.smem_len, /* bytes */
PROT_READ | PROT_WRITE, /* prot */
MAP_SHARED, /* flags */
FrameBufferFD, /* fd */
0 /* offset */ );
if (FrameBuffer == ( void *) - 1) {
fprintf(stderr, "error: unable to mmap framebuffer/n" );
exit(1);
}
}
void closeFBDEV( void ) {
munmap(FrameBuffer, FixedInfo.smem_len);
close(FrameBufferFD);
}
int main() {
openFBDEV();
fprintf(stderr, "openFBDEV finish/n" );
memset(FrameBuffer, 128, FixedInfo.smem_len);
sleep(5);
closeFBDEV();
fprintf(stderr, "closeFBDEV finish/n" );
return 0;
}
補充一點，比如直接寫屏操作：
u_int * screen_memory = (u_int*)mmap(0,
buffer_size,//fixinfo.smem_len,
PROT_READ | PROT_WRITE,
MAP_SHARED,
fbdev,
0);
for(i=0;i *(screen_memory+i) = 0xff; //red
sleep(2);
for(i=0;i *(screen_memory+i) = 0xff00;//green
sleep(2);
for(i=0;i *(screen_memory+i) = 0xff0000;//blue
sleep(2);
本文來自CSDN博客，轉載請標明出處：http://blog.csdn.net/lanmanck/archive/2009/08/07/4423383.aspx