add real vsync test for screen synchronization

README.md

@@ -16,6 +16,31 @@ link.exe /nologo /SUBSYSTEM:EFI_APPLICATION /ENTRY:EFI_MAIN /MACHINE:X64 space.o
 The compiled BOOTX64.EFI program must be placed in the EFI/BOOT/ directory of an EFI partition on a disk using a GPT. <br>
 The program can be run by entering the firmware settings, turning off secure boot, and selecting the disk as the device to boot from. 
 
+## Building on Linux
+
+### Prerequisites
+Install the required tools:
+```bash
+sudo apt-get install asmc-linux qemu-system-x86 ovmf dosfstools
+```
+
+### Build
+Build the game and create an ESP disk image:
+```bash
+sudo ./build.sh
+```
+
+### Run in QEMU
+Launch the game in QEMU with UEFI:
+```bash
+./run_qemu.sh
+```
+
+The game should boot automatically. If you see the UEFI Shell instead, type:
+```
+FS0:
+\EFI\BOOT\BOOTX64.efi
+```
 
 ## Built in Options
 ### Hardware upscaling

build.sh

@@ -0,0 +1,64 @@
+#!/bin/bash
+
+# Build script for Space Game x64 on Linux
+# Requires: asmc-linux, binutils, dosfstools
+
+set -e
+
+# Test for root privileges (needed for mounting)
+if [ "$EUID" -ne 0 ]; then
+    echo "Please run as root (sudo ./build.sh)"
+    exit 1
+fi
+
+echo "=== Building Space Game x64 for UEFI ==="
+
+# Check for required tools
+echo "Checking for required tools..."
+command -v asmc >/dev/null 2>&1 || { echo "asmc not found. Install with: apt-get install asmc-linux"; exit 1; }
+command -v ld >/dev/null 2>&1 || { echo "ld not found. Install with: apt-get install binutils"; exit 1; }
+command -v mkfs.vfat >/dev/null 2>&1 || command -v /sbin/mkfs.vfat >/dev/null 2>&1 || { echo "mkfs.vfat not found. Install with: apt-get install dosfstools"; exit 1; }
+
+# Clean previous builds
+echo "Cleaning previous builds..."
+rm -f space.o BOOTX64.efi esp.img
+
+# Assemble
+echo "Assembling space.s..."
+asmc -win64 space.s -c -Fo space.o
+if [ ! -f space.o ]; then
+    echo "Assembly failed!"
+    exit 1
+fi
+
+# Link as UEFI PE executable
+echo "Linking as UEFI executable..."
+ld -m i386pep --oformat=pei-x86-64 --subsystem=10 -e EFI_MAIN space.o -o BOOTX64.efi
+if [ ! -f BOOTX64.efi ]; then
+    echo "Linking failed!"
+    exit 1
+fi
+
+# Create ESP disk image
+echo "Creating ESP disk image..."
+dd if=/dev/zero of=esp.img bs=1M count=100 status=none
+/sbin/mkfs.vfat -F 32 esp.img >/dev/null 2>&1 || mkfs.vfat -F 32 esp.img >/dev/null 2>&1
+
+# Mount and copy files
+echo "Mounting ESP image and copying files..."
+mkdir -p esp_mount
+mount -o loop esp.img esp_mount
+mkdir -p esp_mount/EFI/BOOT
+cp BOOTX64.efi esp_mount/EFI/BOOT/
+sync
+umount esp_mount
+rmdir esp_mount
+
+# Fix permissions so user can run QEMU without sudo
+chmod 644 esp.img
+chown $SUDO_USER:$SUDO_USER esp.img BOOTX64.efi 2>/dev/null || true
+
+echo "=== Build complete! ==="
+echo "ESP image created: esp.img"
+echo "EFI executable: BOOTX64.efi"
+echo "Run with: ./run_qemu.sh"

run_qemu.sh

@@ -0,0 +1,42 @@
+#!/bin/bash
+
+# Run Space Game x64 in QEMU with UEFI
+
+set -e
+
+# Check for required files
+if [ ! -f esp.img ]; then
+    echo "Error: esp.img not found. Run ./build.sh first"
+    exit 1
+fi
+
+# Check for QEMU
+command -v qemu-system-x86_64 >/dev/null 2>&1 || { echo "qemu-system-x86_64 not found. Install with: apt-get install qemu-system-x86"; exit 1; }
+
+# Find OVMF firmware
+OVMF=""
+if [ -f /usr/share/ovmf/OVMF.fd ]; then
+    OVMF="/usr/share/ovmf/OVMF.fd"
+elif [ -f /usr/share/OVMF/OVMF_CODE.fd ]; then
+    OVMF="/usr/share/OVMF/OVMF_CODE.fd"
+elif [ -f /usr/share/edk2-ovmf/x64/OVMF_CODE.fd ]; then
+    OVMF="/usr/share/edk2-ovmf/x64/OVMF_CODE.fd"
+else
+    echo "Error: OVMF UEFI firmware not found. Install with: apt-get install ovmf"
+    exit 1
+fi
+
+echo "Starting QEMU with UEFI firmware..."
+echo "The game should auto-boot. If it drops to UEFI Shell, type:"
+echo "  FS0:"
+echo "  \\EFI\\BOOT\\BOOTX64.efi"
+echo ""
+
+# Run QEMU
+qemu-system-x86_64 \
+    -cpu qemu64,+rdrand \
+    -bios "$OVMF" \
+    -drive file=esp.img,format=raw \
+    -m 2048
+
+echo "QEMU exited."

space.s

@@ -4288,15 +4288,20 @@ EFI_MAIN PROC
 		OR RAX, RDX
 		ADD RAX, CYCLESPERFRAME
 		MOV NEXTFRAME@, RAX		;SET  TIME TO NEXT FRAME
+
+	; WAIT WITH VGA VSYNC FOR NEXT FRAME
 	WAITNEXTFRAME:
-		RDTSC
-		SHL RDX, 20H
-		OR RAX, RDX
-		CMP NEXTFRAME@, RAX
-		JA WAITNEXTFRAME				;IF NOT AT NEXT FRAME TIME, KEEP WAITING
-		ADD RAX, CYCLESPERFRAME
-		MOV NEXTFRAME@, RAX		;SET  TIME TO NEXT FRAME
-
+		MOV DX, 03DAH       ; VGA STATUS REGISTER
+	WAITNEXTFRAME_L1:
+		IN AL, DX           ; READ STATUS
+		TEST AL, 8          ; TEST VSYNC BIT
+		JNZ WAITNEXTFRAME_L1  ; WAIT WHILE IN RETRACE
+	WAITNEXTFRAME_L2:
+		IN AL, DX           ; READ STATUS
+		TEST AL, 8          ; TEST VSYNC BIT
+		JZ WAITNEXTFRAME_L2   ; WAIT UNTIL RETRACE STARTS
+	; TODO: HERE YOU COULD SWITCH THE FRAMEBUFFER FOR DOUBLE BUFFERING
+
 	RUNFRAME:
 		MOV RAX, TITLEON
 		CMP AL, 00H