From eed98067d0e42b2d7a812e25c48fa482cc969b37 Mon Sep 17 00:00:00 2001
From: Andre Weissflog <floooh@gmail.com>
Date: Fri, 9 Aug 2024 18:21:45 +0200
Subject: [PATCH] kc85 implement patch callback

---
 emus/kc85/kc85.zig   | 26 ++++++++++++++++++++++++--
 src/systems/kc85.zig |  1 -
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/emus/kc85/kc85.zig b/emus/kc85/kc85.zig
index ad894dc..2e2a747 100644
--- a/emus/kc85/kc85.zig
+++ b/emus/kc85/kc85.zig
@@ -87,8 +87,7 @@ export fn frame() void {
     });
     if (file_loaded.once()) {
         if (args.file_data) |file_data| {
-            // FIXME: patch-func
-            sys.load(.{ .data = file_data, .start = true, .patch = null }) catch |err| {
+            sys.load(.{ .data = file_data, .start = true, .patch = .{ .func = patch } }) catch |err| {
                 print("Failed to load file into emulator with {}", .{err});
             };
         }
@@ -196,6 +195,29 @@ pub fn main() void {
     });
 }
 
+// game patcher callback
+fn patch(image_name: []const u8, userdata: usize) void {
+    _ = userdata;
+    if (std.mem.startsWith(u8, image_name, "JUNGLE     ")) {
+        // patch start level 1 into memory
+        sys.mem.wr(0x36B7, 1);
+        sys.mem.wr(0x3697, 1);
+        for (0..5) |idx| {
+            const idx16: u16 = @truncate(idx);
+            const b = sys.mem.rd(0x36B6 +% idx16);
+            sys.mem.wr(0x1770 +% idx16, b);
+        }
+    } else if (std.mem.startsWith(u8, image_name, "DIGGER  COM\x01")) {
+        // time for delay loop 0x0160 instead of 0x0260
+        sys.mem.wr16(0x09AA, 0x0160);
+        // OR L instead of OR (HL)
+        sys.mem.wr(0x3D3A, 0xB5);
+    } else if (std.mem.startsWith(u8, image_name, "DIGGERJ")) {
+        sys.mem.wr16(0x09AA, 0x0260); // not a bug
+        sys.mem.wr(0x3D3A, 0xB5);
+    }
+}
+
 // command line args
 const Args = struct {
     const Module = struct {
diff --git a/src/systems/kc85.zig b/src/systems/kc85.zig
index cb3764b..4d63351 100644
--- a/src/systems/kc85.zig
+++ b/src/systems/kc85.zig
@@ -105,7 +105,6 @@ pub fn Type(comptime model: Model) type {
         // runtime options
         pub const Options = struct {
             audio: Audio.Options,
-            // FIXME: patch callback
             roms: switch (model) {
                 .KC852 => struct {
                     caos22: []const u8,