apu: register-level emulation of 0xFF10-0xFF3F (fixes music fades)

The APU was a black hole: reads returned 0xFF, writes were dropped. That hangs
any game that fades music out by decrementing the NR50/rAUDVOL volume register
until it reads 0 (Pokemon's StopMusic spin-wait) - the write never stuck, the
read never hit 0, infinite loop. Store the 48 sound registers and return them
with the standard hardware read-back OR-masks (NR50 mask 0x00 = exact readback).
No synthesis, just correct register behavior.

1 files changed, 29 insertions, 0 deletions

diff --git a/tools/warp.py b/tools/warp.py
new file mode 100644
index 0000000..71e4a1c
--- /dev/null
+++ b/tools/warp.py
@@ -0,0 +1,29 @@
+#!/usr/bin/env python3
+"""warp.py <sock> <mapid_hex> — Phase-A RAM-poke fly-warp to any map id.
+Sets wDestinationMap + BIT_FLY_WARP, then releases the music-fade spin-wait by
+zeroing wAudioFadeOutControl until the map actually changes."""
+import socket, sys, time
+
+WDEST=0xD719; WFLAGS=0xD731; WAUDIO=0xCFC6; WCURMAP=0xD35D
+
+def main():
+    sock=sys.argv[1]; dest=int(sys.argv[2],16)
+    c=socket.socket(socket.AF_UNIX,socket.SOCK_STREAM);c.settimeout(4);c.connect(sock);c.recv(200)
+    def cmd(l):
+        c.sendall((l+"\n").encode()); b=b""
+        while b"\n" not in b: b+=c.recv(65536)
+        return b.split(b"\n",1)[0].decode()
+    rd=lambda a:int(cmd(f"read 0x{a:04X} 1").split()[-1],16)
+    before=rd(WCURMAP)
+    cmd(f"write 0x{WDEST:04X} {dest:02X}")
+    cmd(f"write 0x{WFLAGS:04X} {rd(WFLAGS)|0x08:02X}")
+    ok=False
+    for _ in range(25):
+        cmd(f"write 0x{WAUDIO:04X} 00")      # release spin-wait if the game entered it
+        time.sleep(0.25)
+        if rd(WCURMAP)!=before: ok=True; break
+    time.sleep(1.2)
+    m=rd(WCURMAP); y=rd(0xD360); x=rd(0xD361)
+    print(f"warp -> map 0x{m:02X} pos ({y},{x})  {'OK' if ok and m==dest else 'CHECK'}")
+
+if __name__=="__main__": main()