我正在尝试为Linux直接写入到framebuffer/dev/fb0的应用程序。为了使它具有双缓冲功能,我尝试使虚拟屏幕的大小增加一倍。这是我写的程序:在fb_var_screeninfo中设置yres_virtual时发生无效参数错误
struct fb_var_screeninfo screeninfo_var;
struct fb_fix_screeninfo screeninfo_fixed;
unsigned int* screenbuffer;
void gfx_init()
{
fb0 = open("/dev/fb0", O_RDWR);
if(fb0 == 0)
error("Could not open framebuffer located in /dev/fb0!");
if (ioctl(fb0, FBIOGET_FSCREENINFO, &screeninfo_fixed) == -1)
error("Could not retrive fixed screen info!");
if (ioctl(fb0, FBIOGET_VSCREENINFO, &screeninfo_var) == -1)
error("Could not retrive variable screen info!");
screeninfo_var.xres_virtual = screeninfo_var.xres;
screeninfo_var.yres_virtual = screeninfo_var.yres * 2;
screeninfo_var.width = screeninfo_var.xres;
screeninfo_var.height = screeninfo_var.yres;
screeninfo_var.xoffset = 0;
screeninfo_var.yoffset = 0;
if (ioctl(fb0, FBIOPUT_VSCREENINFO, &screeninfo_var) == -1)
error("Could not set variable screen info!");
info("Detected monitor of %ix%i pixels using %i bit colors.",screeninfo_var.xres, screeninfo_var.yres, screeninfo_var.bits_per_pixel);
screenbuffersize = screeninfo_var.xres_virtual * screeninfo_var.yres_virtual * screeninfo_var.bits_per_pixel/8;
screenbuffer = (unsigned int *)mmap(0, screenbuffersize, PROT_READ | PROT_WRITE, MAP_SHARED, fb0, 0);
if((long)screenbuffer == 0 || (long)screenbuffer == -1)
error("Failed to map framebuffer to device memory!");
}
上ioctl(fb0, FBIOPUT_VSCREENINFO, &screeninfo_var)
程序failes报告错误无效的参数。当删除行screeninfo_var.yres_virtual = screeninfo_var.yres * 2;
它运行良好(但没有双缓冲)。
有人看到我在这里做错了吗?
你有没有想出解决办法?我目前有类似的问题。 – 2016-01-16 20:18:52