+#include <stdio.h>
+#include "gfx.h"
+#include "vbe.h"
+#include "vga.h"
+#include "cdpmi.h"
+
+#ifdef __DJGPP__
+#include <sys/nearptr.h>
+#define REALPTR(s, o) (void*)(((uint32_t)(s) << 4) - __djgpp_base_address + ((uint32_t)(o)))
+#else
+#define REALPTR(s, o) (void*)(((uint32_t)(s) << 4) + ((uint32_t)(o)))
+#endif
+
+#define SAME_BPP(a, b) \
+ ((a) == (b) || ((a) == 16 && (b) == 15) || ((a) == 15 && (b) == 16) || \
+ ((a) == 32 && (b) == 24) || ((a) == 24 && (b) == 32))
+
+static int vbe_init_ver;
+static struct vbe_info vbe;
+static int mode, pgsize, fbsize;
+static struct vbe_mode_info mode_info;
+
+static void *vpgaddr[2];
+static int fbidx;
+
+static int init_vbe(void)
+{
+ if(vbe_info(&vbe) == -1) {
+ return -1;
+ }
+
+ vbe_print_info(stdout, &vbe);
+ fflush(stdout);
+
+ vbe_init_ver = VBE_VER_MAJOR(vbe.ver);
+ return 0;
+}
+
+void *set_video_mode(int xsz, int ysz, int bpp)
+{
+ int i, nmodes;
+ int best_match_mode = -1;
+ struct vbe_mode_info minf;
+
+ if(!vbe_init_ver) {
+ if(init_vbe() == -1) {
+ fprintf(stderr, "failed to initialize VBE\n");
+ return 0;
+ }
+ if(vbe_init_ver < 2) {
+ fprintf(stderr, "VBE >= 2.0 required\n");
+ return 0;
+ }
+ }
+
+ mode = -1;
+
+ for(i=0; i<nmodes; i++) {
+ vbe_mode_info(vbe.modes[i], &minf);
+ if(minf.xres != xsz || minf.yres != ysz) continue;
+ if(minf.bpp == bpp) {
+ mode = vbe.modes[i];
+ break;
+ }
+ if(SAME_BPP(minf.bpp, bpp)) {
+ best_match_mode = mode;
+ }
+ }
+
+ if(mode == -1) {
+ if(best_match_mode == -1) {
+ fprintf(stderr, "failed to find requested video mode (%dx%d %d bpp)\n", xsz, ysz, bpp);
+ return 0;
+ }
+ mode = best_match_mode;
+ }
+
+ vbe_mode_info(mode, &mode_info);
+ printf("setting video mode %x: (%dx%d %d)\n", (unsigned int)mode, mode_info.xres,
+ mode_info.yres, mode_info.bpp);
+
+ if(vbe_setmode(mode) == -1) {
+ fprintf(stderr, "failed to set video mode\n");
+ return 0;
+ }
+
+ pgsize = mode_info.xres * mode_info.yres * (bpp / 8);
+ fbsize = mode_info.num_img_pages * pgsize;
+
+ vpgaddr[0] = (void*)dpmi_mmap(mode_info.fb_addr, fbsize);
+
+ if(mode_info.num_img_pages > 1) {
+ vpgaddr[1] = (char*)vpgaddr[0] + pgsize;
+ fbidx = 1;
+ page_flip(FLIP_NOW); /* start with the second page visible */
+ } else {
+ fbidx = 0;
+ vpgaddr[1] = 0;
+ }
+
+ return vpgaddr[0];
+}
+
+int set_text_mode(void)
+{
+ vga_setmode(3);
+ return 0;
+}
+
+void *page_flip(int vsync)
+{
+ if(!vpgaddr[1]) {
+ /* page flipping not supported */
+ return vpgaddr[0];
+ }
+
+ vbe_swap(fbidx ? pgsize : 0, vsync ? VBE_SWAP_VBLANK : VBE_SWAP_NOW);
+ fbidx = (fbidx + 1) & 1;
+
+ return vpgaddr[fbidx];
+}