megaed-sv: implement ROM load/run

[megadrive.git] / megaed-sv / asmtools.s

diff --git a/megaed-sv/asmtools.s b/megaed-sv/asmtools.s
index db93940..d1e1316 100644 (file)
--- a/megaed-sv/asmtools.s
+++ b/megaed-sv/asmtools.s
@@ -6,7 +6,7 @@
 .endm
 
 
-.globl read_joy_responses /* u8 *rbuf */
+.global read_joy_responses /* u8 *rbuf */
 read_joy_responses:
     ldarg       0, 0, a1
     movem.l     d2-d7, -(sp)
@@ -49,4 +49,49 @@ read_joy_responses:
     rts
 
 
+.global run_game /* u16 mapper */
+run_game:
+       move.w          #0x2700, sr
+    ldarg       0, 0, d7
+    move.l      #0xa10000, a7
+    moveq.l     #0x00, d1
+    move.b      #0xff, d2
+    move.b      d1, (0x0b,a7) /* CtrlB */
+    move.b      d1, (0x0d,a7) /* CtrlC */
+    move.b      d2, (0x0f,a7) /* TxDataA */
+    move.b      d1, (0x13,a7) /* S-CtrlA */
+    move.b      d2, (0x15,a7) /* TxDataB */
+    move.b      d1, (0x19,a7) /* S-CtrlB */
+    move.b      d2, (0x1b,a7) /* TxDataC */
+    move.b      d1, (0x1f,a7) /* S-CtrlC */
+
+    move.l      #0xff0000, a1
+    move.l      #0x10000/4/4-1, %d0
+0:
+    move.l      d1, (%a1)+
+    move.l      d1, (%a1)+
+    move.l      d1, (%a1)+
+    move.l      d1, (%a1)+
+    dbra        d0, 0b
+
+    lea         (run_game_code,pc), a0
+    move.l      #0xfff000, a1
+    move.l      #(run_game_code_end - run_game_code)/2-1, d0
+0:
+    move.w      (%a0)+, (%a1)+
+    dbra        d0, 0b
+    jmp         0xfff000
+
+run_game_code:
+    move.w      #0x3210, (0xA13006)
+
+    move.w      d7, (0xA13010)
+    move.w      #0, (0xA13000)
+    
+    move.l      (0x00), a7
+    move.l      (0x04), a0
+    jmp         (a0)
+run_game_code_end:
+
+
 # vim:filetype=asmM68k:ts=4:sw=4:expandtab