我正在嘗試爲Linux直接寫入到framebuffer/dev/fb0的應用程序。爲了使它具有雙緩衝功能,我嘗試使虛擬屏幕的大小增加一倍。這是我寫的程序:在fb_var_screeninfo中設置yres_virtual時發生無效參數錯誤
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報告錯誤無效的參數。當刪除行screeninfo_var.yres_virtual = screeninfo_var.yres * 2;
它運行良好(但沒有雙緩衝)。
有人看到我在這裏做錯了嗎?
你有沒有想出解決辦法?我目前有類似的問題。 – 2016-01-16 20:18:52