programs: Add Uxn emulator.

programs/emulator/uxn/src/kolibri.zig

@@ -538,6 +538,20 @@ pub fn writeFile(pathname: [*:0]const u8, offset: u64, buffer: []u8) !u32 {
     };
 }
 
+pub fn fileGetSize(pathname: [*:0]const u8) !u64 {
+    var ret: [10]u32 = undefined;
+    const info: FileInfo = .{
+        .subfn = 5,
+        .offset = 0,
+        .size = 0,
+        .buffer = @intFromPtr(&ret),
+        .pathptr = @ptrCast(pathname),
+    };
+    if (syscall1(SYS.file, @intFromPtr(&info)) != 0)
+        return error.Unexpected;
+    return ret[8] | (@as(u64, ret[9]) << 32);
+}
+
 pub fn deleteFile(pathname: [*:0]const u8) !void {
     const info: FileInfo = .{
         .subfn = 8,

programs/emulator/uxn/src/main.zig

@@ -98,7 +98,8 @@ const emu = struct {
                                 const buffer = getFilePortSlice(dev, ports.write);
                                 var ret: u32 = 0;
                                 if (append) {
-                                    ret = kos.writeFile(pathname, file_offsets[idx], buffer) catch |err| blk: {
+                                    const offset: u32 = @intCast(kos.fileGetSize(pathname) catch 0);
+                                    ret = kos.writeFile(pathname, offset, buffer) catch |err| blk: {
                                         if (err == error.FileNotFound) {
                                             break :blk kos.createFile(pathname, buffer) catch 0;
                                         } else {