-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathmacros.asm
69 lines (48 loc) · 2.33 KB
/
macros.asm
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
;----------------------------------------------------------
; MICHAEL JACKSON'S MOONWALKER DECOMPILATION
; (C) HARRY CLARK 2023
;----------------------------------------------------------
;----------------------------------------------------------
; THIS FILE DEFINES THE MACROS FOR ARGUMENTS AND
; AND THEIR HANDLERS
;----------------------------------------------------------
NULL_ARG: MACRO
ARG_VALUE: EQU 1
@LOOP\@ DC.B 1, %ARG_VALUE, 0
DC.B 1, %ARG_VALUE, \2
BNE.S @LOOP\@
ENDM
ENABLE_VSRAM: EQU 0
VSRAM_ADDR: EQU 3
SUPPORT_VSRAM: MACRO
@LOOP\@ if ENABLE_VSRAM = 1
DC.B $2A3F + VSRAM_ADDR << 3, $20 ;; ASSUME THE LENGTH OF THE
;; VSRAM CONSTANT, ACCESS THE ADDRESS IN PROPORTION TO THAT
else
DC.L $20202020 ;; ENABLE THE VSRAM ACCORDINGLY
DC.L $20202020 ;; AND DEFINE WHICH ADDRESS IT SHOULD
DC.B " " ;; EXECUTE IT'S RUNTIME AT
BNE.S @LOOP\@
ENDM
;; DEFINE THE BUS ERROR BRANCH LOOP
;; AS DEMONSTRATED BY THE VECTOR TABLE
BUS_ERROR: MACRO
ERR_VALUE: EQU $0000008
NOP
NOP
BRA.B ERR_VALUE
ENDM
;; DEFINE THE TRAP COROUTINE TO FREEZE THE 68000 FROM PERFROMING ILLEGAL INSTRUCTIONS
;; CREATES AN ADDRESS DIFFERENCE TO DISCERN BETWEEN VALUES ON GPR'S 14 AND 16
;;
VDP_ADDR_DIF: VALUE, ADDR,((ADDR &$3FFF) << 16) || ((ADDR $0000) >> 14)
DMA_VDP: MACRO SOURCE, DEST, LEN, TYPE
LEA $C00004.L, A5 ;; LOAD THE EFFECTIVE ADDRESS OF THE VDP CONTROL IN GPR A5
;; SEE https://segaretro.org/Sega_Mega_Drive/VDP_general_usage#Registers
LEA $C00000.L, A6
MOVE.W $0002, A5
ENDM
ZERO_OFFSET = 0
;----------------------------------------------------------
; END OF FILE
;----------------------------------------------------------