ARK-OS/arkos/system/core/fb_helper.c

/*
 * ArkOS Framebuffer Helper
 * ------------------------
 * Thin C wrappers around Linux framebuffer ioctl calls.
 * These are called from Swift via @_silgen_name interop since
 * Swift cannot directly invoke ioctl with its variadic signature.
 *
 * Functions:
 *   get_vinfo()     — Query variable screen info (resolution, bpp)
 *   get_finfo()     — Query fixed screen info (line length, memory size)
 *   set_vinfo()     — Set variable screen info (mode changes)
 *   pan_display()   — Page flip (swap front/back buffer)
 *   blank_display() — Blank or unblank the display (power management)
 */

#include <sys/ioctl.h>
#include <linux/fb.h>

/* Query the current video mode (resolution, bits per pixel, etc.) */
int get_vinfo(int fd, struct fb_var_screeninfo *vinfo) {
    return ioctl(fd, FBIOGET_VSCREENINFO, vinfo);
}

/* Query fixed screen parameters (line length, framebuffer size, etc.) */
int get_finfo(int fd, struct fb_fix_screeninfo *finfo) {
    return ioctl(fd, FBIOGET_FSCREENINFO, finfo);
}

/* Set variable screen info (used for mode changes and virtual resolution) */
int set_vinfo(int fd, struct fb_var_screeninfo *vinfo) {
    return ioctl(fd, FBIOPUT_VSCREENINFO, vinfo);
}

/* Page flip — sets the visible portion of the virtual framebuffer */
int pan_display(int fd, struct fb_var_screeninfo *vinfo) {
    return ioctl(fd, FBIOPAN_DISPLAY, vinfo);
}

/* Blank or unblank the display (0=unblank, 1=blank for power saving) */
int blank_display(int fd, int mode) {
    return ioctl(fd, FBIOBLANK, mode);
}