+ vbe_swap(backidx ? pgsize : 0, vsync ? VBE_SWAP_VBLANK : VBE_SWAP_NOW);
+ frontidx = backidx;
+ backidx = (backidx + 1) & 1;
+
+ return vpgaddr[backidx];
+}
+
+
+static void blit_frame_lfb(void *pixels, int vsync)
+{
+ demo_post_draw(pixels);
+
+ if(vsync) wait_vsync();
+ memcpy64(vpgaddr[frontidx], pixels, pgsize >> 3);
+}
+
+static void blit_frame_banked(void *pixels, int vsync)
+{
+ int sz, offs, pending;
+ unsigned char *pptr = pixels;
+
+ demo_post_draw(pixels);
+
+ if(vsync) wait_vsync();
+
+ /* assume initial window offset at 0 */
+ offs = 0;
+ pending = pgsize;
+ while(pending > 0) {
+ sz = pending > 65536 ? 65536 : pending;
+ /*memcpy64(VMEM_PTR, pptr, sz >> 3);*/
+ memcpy(VMEM_PTR, pptr, sz);
+ pptr += sz;
+ pending -= sz;
+ offs += curmode->win_64k_step;
+ vbe_setwin(0, offs);
+ }
+ vbe_setwin(0, 0);
+}
+
+static uint32_t calc_mask(int sz, int pos)
+{
+ uint32_t mask = 0;
+ while(sz-- > 0) {
+ mask = (mask << 1) | 1;
+ }
+ return mask << pos;
+}
+
+#define MSR_MTRRCAP 0xfe
+#define MSR_MTRRDEFTYPE 0x2ff
+#define MSR_MTRRBASE(x) (0x200 | ((x) << 1))
+#define MSR_MTRRMASK(x) (0x201 | ((x) << 1))
+#define MTRRDEF_EN 0x800
+#define MTRRCAP_HAVE_WC 0x400
+#define MTRRMASK_VALID 0x800
+
+#define MTRR_WC 1
+
+static int get_page_memtype(uint32_t addr, int num_ranges)
+{
+ int i;
+ uint32_t rlow, rhigh;
+ uint32_t base, mask;
+
+ for(i=0; i<num_ranges; i++) {
+ get_msr(MSR_MTRRMASK(i), &rlow, &rhigh);
+ if(!(rlow & MTRRMASK_VALID)) {
+ continue;
+ }
+ mask = rlow & 0xfffff000;
+
+ get_msr(MSR_MTRRBASE(i), &rlow, &rhigh);
+ base = rlow & 0xfffff000;
+
+ if((addr & mask) == (base & mask)) {
+ return rlow & 0xff;
+ }
+ }
+
+ get_msr(MSR_MTRRDEFTYPE, &rlow, &rhigh);
+ return rlow & 0xff;
+}
+
+static int check_wrcomb_enabled(uint32_t addr, int len, int num_ranges)
+{
+ while(len > 0) {
+ if(get_page_memtype(addr, num_ranges) != MTRR_WC) {
+ return 0;
+ }
+ addr += 4096;
+ len -= 4096;
+ }
+ return 1;
+}
+
+static int alloc_mtrr(int num_ranges)
+{
+ int i;
+ uint32_t rlow, rhigh;
+
+ for(i=0; i<num_ranges; i++) {
+ get_msr(MSR_MTRRMASK(i), &rlow, &rhigh);
+ if(!(rlow & MTRRMASK_VALID)) {
+ return i;
+ }
+ }
+ return -1;
+}
+
+static void enable_wrcomb(uint32_t addr, int len)
+{
+ int num_ranges, mtrr;
+ uint32_t rlow, rhigh;
+ uint32_t def, mask;
+
+ if(len <= 0 || (addr | (uint32_t)len) & 0xfff) {
+ fprintf(stderr, "failed to enable write combining, unaligned range: %p/%x\n",
+ (void*)addr, (unsigned int)len);
+ return;
+ }
+
+ get_msr(MSR_MTRRCAP, &rlow, &rhigh);
+ num_ranges = rlow & 0xff;
+
+ printf("enable_wrcomb: addr=%p len=%x\n", (void*)addr, (unsigned int)len);
+
+ if(!(rlow & MTRRCAP_HAVE_WC)) {
+ fprintf(stderr, "failed to enable write combining, processor doesn't support it\n");
+ return;
+ }
+
+ if(check_wrcomb_enabled(addr, len, num_ranges)) {
+ return;
+ }
+
+ if((mtrr = alloc_mtrr(num_ranges)) == -1) {
+ fprintf(stderr, "failed to enable write combining, no free MTRRs\n");
+ return;
+ }