6502 Assembler (part 1 of 3)
Eric C. Brown
brownc at utah-cs.UUCP
Sat May 4 01:49:59 AEST 1985
# Due to overwhelming demand, (15 requests in 3 days), here is the 6502
# assembler in C:
#!/bin/sh
# This is a shell archive, meaning:
# 1. Remove everything above the #!/bin/sh line.
# 2. Save the resulting text in a file.
# 3. Execute the file with /bin/sh (not csh) to create the files:
# assmtest
# assmtest.l
# makefile
# user.nr
# This archive created: Tue Apr 2 14:21:42 1985
# By: James Van Ornum (AT&T-Bell Laboratories)
export PATH; PATH=/bin:$PATH
if test -f 'assmtest'
then
echo shar: over-writing existing file "'assmtest'"
fi
cat << \SHAR_EOF > 'assmtest'
;******************************************
; Test file for the 6502 assembler - as6502
; assemble as
; as6502 -nisv assmtest
; and compare output with assmtest.l
;******************************************
;; comment treatment
;******************************************
aa = $10; ';' immediately after the '0'
B = $20 space to comment subfield
C = $30 tab to comment subfield
DEFGHIjkl = $FFEE
D =DEFGHIjkl
;******************************************
; Number formats
;******************************************
start *= $4 ; location counter adjust
.byte %0101 ; binary number
.byte 022, at 22 ; octal numbers - two forms
.byte 22 ; decimal number
.byte $22,$ff,$FF ; hex - upper/lower case
.byte 'a,'b ; single ASCII characters
;******************************************
;; ASCII character string
;******************************************
.byte "abcd\t\n",0 ; tab and new line escaped
;******************************************
; Operation checks
;******************************************
.word aa+B ; addition
.word aa-B ; subtraction
.word aa*B ; multiplication
.word B/aa ; division
.word C%B ; modulo
.word B^C ; exclusive OR
.word ~C ; one's complement
.word B&C ; logical AND
.word aa|B ; logical OR
.word <D ; low byte
.word >D ; high byte
.word * ; current location
.word aa,B,C
.word B*[aa+C] ; one level of parenthesis
.dbyt D ; high byte-low byte word
.word D/256,D%256
;******************************************
; Addressing Mode Check
;******************************************
*=$0100
lda =aa ; immediate addressing
lda #aa ; immediate addressing, alternate
lda D ; direct addessing
LDA aa ; page zero addressing, aa < 256
a1 = 512
a2 = 500
lda a1-a2 ; also page zero
asl A ; accumulator addressing
AsL a ; accumulator addressing also
brk ; implied addressing
lda (aa,X) ; indirect,X addressing
lda (aa),Y ; indirect,Y addressing
lda aa,X ; zero page,X addressing
lda D,X ; absolute,X addressing
lda D,Y ; absolute,Y addressing
bcc *-$10 ; relative addressing
jmp (D) ; indirect addressing
ldx aa,Y ; zero page,Y addressing
ldx aa,y ; alternate index name
.nlst
;******************************************
; opcode check
;******************************************
adc =01
and =01
asl A
bcc *+2
bcs *+2
beq *+2
bit $01
bmi *+2
bne *+2
bpl *+2
brk
bvc *+2
bvs *+2
clc
cld
cli
clv
cmp =01
cpx =01
cpy =01
dec $01
dex
dey
eor =01
inc $01
inx
iny
jmp *+3
jsr *+3
lda =01
ldx =01
ldy =01
lsr A
nop
ora =01
pha
php
pla
plp
rol A
ror A
rti
rts
sbc =01
sec
sed
sei
sta $01
stx $01
sty $01
tax
tay
tsx
txa
txs
tya
SHAR_EOF
if test -f 'assmtest.l'
then
echo shar: over-writing existing file "'assmtest.l'"
fi
cat << \SHAR_EOF > 'assmtest.l'
as6502 - version 4.1 - 11/5/84 - JHV
1 ;******************************************
2 ; Test file for the 6502 assembler - as6502
3 ; assemble as
4 ; as6502 -nisv assmtest
5 ; and compare output with assmtest.l
6 ;******************************************
7 ; ; comment treatment
8 ;******************************************
9 0010 aa = $10 ; ';' immediately after the '0'
10 0020 B = $20 space to comment subfield
11 0030 C = $30 tab to comment subfield
12 FFEE DEFGHIjkl = $FFEE
13 FFEE D =DEFGHIjkl
14 ;******************************************
15 ; Number formats
16 ;******************************************
17 0004 start *= $4 ; location counter adjust
18 0004 05 .byte %0101 ; binary number
19 0005 12 12 .byte 022, at 22 ; octal numbers - two forms
20 0007 16 .byte 22 ; decimal number
21 0008 22 FF FF .byte $22,$ff,$FF ; hex - upper/lower case
22 000B 61 62 .byte 'a,'b ; single ASCII characters
23 ;******************************************
24 ; ; ASCII character string
25 ;******************************************
26 000D 61 62 63 .byte "abcd\t\n",0 ; tab and new line escaped
0010 64 09 0A
0013 00
27 ;******************************************
28 ; Operation checks
29 ;******************************************
30 0014 30 00 .word aa+B ; addition
31 0016 F0 FF .word aa-B ; subtraction
32 0018 00 02 .word aa*B ; multiplication
33 001A 02 00 .word B/aa ; division
34 001C 10 00 .word C%B ; modulo
35 001E 10 00 .word B^C ; exclusive OR
36 0020 CF FF .word ~C ; one's complement
37 0022 20 00 .word B&C ; logical AND
38 0024 30 00 .word aa|B ; logical OR
39 0026 EE 00 .word <D ; low byte
40 0028 FF 00 .word >D ; high byte
41 002A 2A 00 .word * ; current location
42 002C 10 00 .word aa,B,C
002E 20 00
0030 30 00
43 0032 00 08 .word B*[aa+C] ; one level of parenthesis
44 0034 FF EE .dbyt D ; high byte-low byte word
45 0036 FF 00 .word D/256,D%256
0038 EE 00
46 ;******************************************
47 ; Addressing Mode Check
48 ;******************************************
49 0100 *=$0100
50 0100 A9 10 lda =aa ; immediate addressing
51 0102 A9 10 lda #aa ; immediate addressing, alternate
52 0104 AD EE FF lda D ; direct addessing
53 0107 A5 10 LDA aa ; page zero addressing, aa < 256
54 0200 a1 = 512
55 01F4 a2 = 500
56 0109 A5 0C lda a1-a2 ; also page zero
57 010B 0A asl A ; accumulator addressing
58 010C 0A AsL a ; accumulator addressing also
59 010D 00 brk ; implied addressing
60 010E A1 10 lda (aa,X) ; indirect,X addressing
61 0110 B1 10 lda (aa),Y ; indirect,Y addressing
62 0112 B5 10 lda aa,X ; zero page,X addressing
63 0114 BD EE FF lda D,X ; absolute,X addressing
64 0117 B9 EE FF lda D,Y ; absolute,Y addressing
65 011A 90 EE bcc *-$10 ; relative addressing
66 011C 6C EE FF jmp (D) ; indirect addressing
67 011F B6 10 ldx aa,Y ; zero page,Y addressing
68 0121 B6 10 ldx aa,y ; alternate index name
70 ;******************************************
71 ; opcode check
72 ;******************************************
73 0123 69 01 adc =01
74 0125 29 01 and =01
75 0127 0A asl A
76 0128 90 00 bcc *+2
77 012A B0 00 bcs *+2
78 012C F0 00 beq *+2
79 012E 24 01 bit $01
80 0130 30 00 bmi *+2
81 0132 D0 00 bne *+2
82 0134 10 00 bpl *+2
83 0136 00 brk
84 0137 50 00 bvc *+2
85 0139 70 00 bvs *+2
86 013B 18 clc
87 013C D8 cld
88 013D 58 cli
89 013E B8 clv
90 013F C9 01 cmp =01
91 0141 E0 01 cpx =01
92 0143 C0 01 cpy =01
93 0145 C6 01 dec $01
94 0147 CA dex
95 0148 88 dey
96 0149 49 01 eor =01
97 014B E6 01 inc $01
98 014D E8 inx
99 014E C8 iny
100 014F 4C 52 01 jmp *+3
101 0152 20 55 01 jsr *+3
102 0155 A9 01 lda =01
103 0157 A2 01 ldx =01
104 0159 A0 01 ldy =01
105 015B 4A lsr A
106 015C EA nop
107 015D 09 01 ora =01
108 015F 48 pha
109 0160 08 php
110 0161 68 pla
111 0162 28 plp
112 0163 2A rol A
113 0164 6A ror A
114 0165 40 rti
115 0166 60 rts
116 0167 E9 01 sbc =01
117 0169 38 sec
118 016A F8 sed
119 016B 78 sei
120 016C 85 01 sta $01
121 016E 86 01 stx $01
122 0170 84 01 sty $01
123 0172 AA tax
124 0173 A8 tay
125 0174 BA tsx
126 0175 8A txa
127 0176 9A txs
128 0177 98 tya
aa 10:00 0010
B 20:00 0020
C 30:00 0030
DEFGHIjkl EE:FF FFEE
D EE:FF FFEE
start 04:00 0004
a1 00:02 0200
a2 F4:01 01F4
SHAR_EOF
if test -f 'makefile'
then
echo shar: over-writing existing file "'makefile'"
fi
cat << \SHAR_EOF > 'makefile'
as6502: assm0.o assm1.o assm2.o assm3.o
cc -s -i assm0.o assm1.o assm2.o assm3.o -o as6502
assm0.o: assm.d1 assm.d2 assm0.c
cc -c -O assm0.c
assm1.o: assm.d1 assm.d2 assm1.c
cc -c -O assm1.c
assm2.o: assm.d1 assm.d2 assm2.c
cc -c -O assm2.c
assm3.o: assm.d1 assm.d2 assm3.c
cc -c -O assm3.c
check: assmtest.l
assmtest.l: as6502
as6502 -nisv assmtest > temp
touch assmtest.l
diff assmtest.l temp
manuals: as6502.l user.l
as6502.l: as6502.1
man -d as6502.1 > as6502.l
user.l: user.nr
nroff user.nr > user.l
clean:
rm assm0.o assm1.o assm2.o assm3.o temp as6502.l user.l
SHAR_EOF
if test -f 'user.nr'
then
echo shar: over-writing existing file "'user.nr'"
fi
cat << \SHAR_EOF > 'user.nr'
.de hd
'sp 3
.tl ''\fBas6502 User Notes\fR'Page %'
'sp 2
..
.de fo
'bp
..
.wh 0 hd
.wh -3 fo
.br
\fBSOURCE LINE FORMAT\fR:
.ti 0.5i
.sp 1
<label> <operation> <operand> <comment>
.sp 1
Each field is terminated by one or more spaces, a tab or a ';' (which
begins the comment field immediately).
.sp
\fBLABEL FIELD\fR:
.sp 1
If first character is ';', entire line is a comment.
If first character is space, label field is null.
Labels are alphanumeric strings beginning
with 'a' through 'z', 'A' through 'Z',
underscore or period followed by any of the above
characters or '0' through '9'.
Currently, labels are limited to 19 characters.
A, X, Y, a, x and y are reserved labels.
.sp
\fBOPERATION FIELD\fR:
.sp 1
Upper and lower case letters are equivalent.
Machine operation mnemonics are:
.in 0.5i
.nf
.sp 1
ADC BMI CLD DEX JSR PHA RTS STY
AND BNE CLI DEY LDA PHP SBC TAX
ASL BPL CLV EOR LDX PLA SEC TAY
BCC BRK CMP INC LDY PLP SED TSX
BCS BVC CPX INX LSR ROL SEI TXA
BEQ BVS CPY INY NOP ROR STA TXS
BIT CLC DEC JMP ORA RTI STX TYA
.in 0
.fi
.sp 1
Pseudo operation mnemonics are:
.in 1.2i
.ti 0.5i
.sp 1
= equate label name to operand field value
(space is not needed to terminate this operation).
.ti 0.5i
*= set location counter to operand field value
(space is not needed to terminate this operation).
.ti 0.5i
.tr*.
*WORD assign 16 bit value of operand field to next
two locations; low byte of value first, then high byte.
.ti 0.5i
*DBYT assign 16 bit value of operand field to next
two locations; high byte of value first, then low byte.
.ti 0.5i
*BYTE assign 8 bit value of operand field to next
location.
.ti 0.5i
*NLST turn listing mode off (this source
line is not listed).
.ti 0.5i
*LIST turn listing mode on (normal mode) (this
source line is not listed).
.tr**
.in 0
.sp 1
\fBOPERAND FIELD\fR:
.sp 1
Operand field expressions use infix notation and are evaluated strictly
from left to right.
No imbedded spaces are permitted.
.sp 1
Operand field terms include labels and numbers.
Asterisk (*) is the label for the location counter value.
Numbers are binary, octal, decimal, hexadecimal or ASCII.
Number type is indicated by the first character of the number string as follows:
.nf
.in 0.5i
.sp 1
% binary prefix
@ or 0 octal prefix
1 - 9 decimal by default (prefix is part of number)
$ hexadecimal prefix
.tr,'
, ASCII character prefix
.tr,,
" ASCII character string prefix and suffix; in the
string, \\t is a tab character, \\n is a new line.
.in 0
.fi
.sp 1
Operand field operations and the corresponding symbols are:
.in 0.5i
.nf
.sp 1
+ addition
- subtraction
/ division
* multiplication
% modulo (remainder after integer division)
^ logical exclusive OR
& logical AND
| logical OR
< low byte
> high byte
.in 0
.fi
.sp 1
\fBERROR MESSAGES\fR:
.in 0.5i
.nf
.sp 1
Invalid operation code
Invalid argument count (when as6502 was invoked)
Open error for file
Creat error for object file 6502.out
Close error
Close error (6502.out)
Symbol table full
Label multiply defined
Sync error (pass 1 symbol value not equal pass 2 symbol value)
Invalid branch address
Operand field missing
Invalid addressing mode
Operand field size error
Undefined symbol in operand field
Invalid operand field
.fi
.in 0
.sp 1
\fBINVOKING as6502\fR:
.sp 1
.ti 0.5i
as6502 {-ilnos} <source files descriptions>
.sp 1
Options:
.in 0.5i
.nf
.sp 1
-i ignore any .nlst pseudo operations
-l list errors only
-n print addresses as <high byte><low byte>,
rather than as <low byte>:<high byte>.
-o generate ASCII object output in file 6502.out,
format is
;<address lo><address hi><data>
-s print symbol table at end of listing
J. H. Van Ornum 11/5/84
SHAR_EOF
# End of shell archive
exit 0
More information about the Comp.sources.unix
mailing list