-
Notifications
You must be signed in to change notification settings - Fork 1
/
block-6502.fs
130 lines (110 loc) · 3.97 KB
/
block-6502.fs
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
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
\ ------ test file 6502.mfc ------
\ A simple 6502 emulation benchmark cas
\ only 11 opcodes are implemented. The memory layout is:
\ 2kB RAM at 0000-07FF, mirrored throughout 0800-7FFF
\ 16kB ROM at 8000-BFFF, mirrored at C000
\ adapted from: https://theultimatebenchmark.org/
here last
variable tl tl !
variable th th !
: forget-6502 tl @ (last) ! th @ (here) ! ;
hex
variable rom $0800 allot
variable ram $4000 allot
: >ram $07FF and ram + ;
: >rom $3FFF and rom + ;
\ 6502 registers
variable reg-a variable reg-x variable reg-y
variable reg-s
variable reg-pc INLINE
variable cycle INLINE
\ 6502 flags
variable flag-c variable flag-n
variable flag-z variable flag-v
: reg-pc+ reg-pc +! ; INLINE
: cycle+ cycle +! ; INLINE
: ws@ dup c@ swap 1+ c@ 0100 * or ;
: cs@ c@ dup 0080 and if 0100 - then ;
: read-byte ( address -- )
dup 8000 < if >ram c@ else >rom c@ then ;
: read-word ( address -- )
dup 8000 < if >ram ws@ else >rom ws@ then ;
: dojmp ( JMP aaaa )
reg-pc @ >rom ws@ reg-pc ! 3 cycle+ ;
: dolda ( LDA aa )
reg-pc @ >rom c@ ram + c@ dup dup reg-a !
flag-z ! 0080 and flag-n ! 1 reg-pc+ 3 cycle+ ;
: dosta ( STA aa )
reg-a @ reg-pc @ >rom c@ ram + c! 1 reg-pc+ 3 cycle+ ;
: dobeq ( BEQ <aa )
flag-z @ 0=
if reg-pc @ >rom cs@ 1+ reg-pc+ else 1 reg-pc+ then
3 cycle+ ;
: doldai ( LDA #aa )
reg-pc @ >rom c@ dup dup reg-a ! flag-z ! 0080 and flag-n !
1 reg-pc+ 2 cycle+ ;
: dodex ( DEX )
reg-x @ 1- 00FF and dup dup reg-x ! flag-z ! 0080 and flag-n !
2 cycle+ ;
: dodey ( DEY )
reg-y @ 1- 00FF and dup dup reg-y ! flag-z ! 0080 and flag-n !
2 cycle+ ;
: doinc ( INC aa )
reg-pc @ >rom c@ ram + dup c@ 1+ 00FF and dup rot rot swap c! dup
flag-z ! 0080 and flag-n ! 1 reg-pc+ 3 cycle+ ;
: doldy ( LDY aa )
reg-pc @ >rom c@ dup dup reg-y ! flag-z ! 0080 and flag-n !
1 reg-pc+ 2 cycle+ ;
: doldx ( LDX #aa )
reg-pc @ >rom c@ dup dup reg-x ! flag-z ! 0080 and flag-n !
1 reg-pc+ 2 cycle+ ;
: dobne ( BNE <aa )
flag-z @ if reg-pc @ >rom cs@ 1+ reg-pc+ else 1 reg-pc+ then
3 cycle+ ;
: doNOP 1 cycle+ ;
: one-instr ( instr -- instr )
dup $4C = if dojmp leave then
dup $A5 = if dolda leave then
dup $85 = if dosta leave then
dup $F0 = if dobeq leave then
dup $D0 = if dobne leave then
dup $A9 = if doldai leave then
dup $CA = if dodex leave then
dup $88 = if dodey leave then
dup $E6 = if doinc leave then
dup $A0 = if doldy leave then
dup $EA = if doNOP leave then
dup $A2 = if doldx leave then
;
: 6502emu ( cycles -- )
begin cycle @ over < NOT
if drop leave then
reg-pc @ >rom c@ 1 reg-pc+
one-instr drop
again ;
variable bp
: b, ( c -- )
bp @ c! 1 bp +! ;
: testcode
rom bp !
A9 b, 00 b, \ start: LDA #0
85 b, 08 b, \ STA 08
A2 b, 0A b, \ LDX #10
A0 b, 0A b, \ loop1: LDY #10
E6 b, 08 b, \ loop2: INC 08
88 b, \ DEY
D0 b, FB b, \ BNE loop2
CA b, \ DEX
D0 b, F6 b, \ BNE loop1
4C b, 00 b, 80 b, \ JMP start
;
: init-vm testcode
0 cycle ! $8000 reg-pc ! ;
: bench6502 $1000
begin
init-vm $1000 6502emu 1- dup
while drop ;
: do-bench start-timer bench6502 elapsed ;
decimal
do-bench
forget-6502