ASM68K and AS. What's the difference?
| ASM68K | AS | Purpose | Example |
|---|---|---|---|
equ |
equ |
Define a value once. Forward references allowed. | label: equ 1+2+3 |
constant |
Same as equ with different syntax. |
constant label,1+2+3 |
|
set or = |
set or = |
Define a reusable value. Forward references not allowed. | label: = 1+2+3 |
equs |
Define a reusable string. Forward references not allowed. Single or double quotes work. To include quotes in the string, use '' where the quote should be. |
label: equs "string"
label2: equs 'it''s a nested quote' |
|
equr |
reg |
Define label to represent a register. | label: equr d0 |
reg |
Define label to represent a series of registers for use with movem. |
label: reg d0-d7/a1-a2 |
|
rsset and rsreset |
Sets the value of __rs. |
rsset $100
rsreset ; __rs = 0 |
|
rs |
Assigns the value of __rs to a label, and advances __rs by the specified amount. |
rsset $100
label: rs.l $10 ; label = $100; __rs = $110 |
|
alias and disable |
Change the names of constants and functions, allowing them to be redefined. | sqrtnew: alias sqrt
disable sqrt |
|
charset |
Redefine the value of an ASCII character. Use without parameters to reset all characters to default. | charset 'a',255 ; a = $FF
charset ; a = $61 |
|
codepage |
Switch between named ASCII character sets. STANDARD is default. |
codepage new
charset 'a',255 ; a = $FF
codepage STANDARD ; a = $61 |
|
enum and nextenum |
Define a series of values which increment. Starts at 0 unless specified. nextenum continues the same series on another line. |
enum x,y,z
dc.b x,y,z ; same as dc.b 0,1,2 |
|
enumconf |
Change the increment for enum. |
enumconf 2
enum x=2,y,z
dc.b x,y,z ; same as dc.b 2,4,6 |
|
save and restore |
Saves current cpu, codepage and other things. |
| ASM68K | AS | Purpose | Example |
|---|---|---|---|
dc.b, dc.w and dc.l |
dc |
Writes a series of bytes, words or longwords. In ASM68K, the automatic even option (ae+) ensures words and longwords are aligned to word. |
dc.b 1,$20,-$30 |
dcb |
Writes a series of bytes, words or longwords of single value. | dcb.b 5,1 ; same as dc.b 1,1,1,1,1 |
|
ds |
ds |
Writes a series of bytes, words or longwords of value 0. | ds.b 5 ; same as dc.b 0,0,0,0,0 |
hex |
Writes a series of bytes. | hex 010203 ; same as dc.b 1,2,3 |
|
datasize and data |
Writes a series of bytes with padding. datasize can be 1 to 256. |
datasize 4
data 1,2 ; same as dc.l 1,2 |
| ASM68K | AS | Purpose | Example |
|---|---|---|---|
org |
org |
Changes program counter to start writing anywhere. Broken in ASM68K - always goes to 0. |
org $100 ; goto address $100 |
rorg |
Add value to program counter. Can be negative. | rorg $100 ; goto *+$100 |
|
even |
Align to word. | dc.b 1,2,3
even ; same as dc.b 1,2,3,0 |
|
padding |
Always align to word when turned on. |
padding on
padding off |
|
cnop x,y |
Align to y and append x bytes. x can be 0 but y cannot. |
cnop 2,16 ; align to 16 and append 2 bytes |
|
obj and objend |
phase and dephase |
Makes program counter believe it's at an address, without actually going there. | obj $100
dc.l * ; writes dc.l $100 to current location
objend |
align |
Align to value. | dc.b 1,2,3
align 2 ; same as dc.b 1,2,3,0 |
| ASM68K | AS | Purpose | Example |
|---|---|---|---|
if, elseif, else and endif/endc |
if, elseif, else and endif |
Assemble different code depending on specified conditions. endif and endc are interchangeable. |
if var=0
dc.b 'var is 0'
elseif var=1
dc.b 'var is 1'
else
dc.b 'var is something else'
endc |
case and endcase |
Alternative to if. Seems broken in ASM68K. |
case var
=0
dc.b 'var is 0'
=1
dc.b 'var is 1'
=?
dc.b 'var is something else'
endcase |
|
switch, case, elsecase and endcase |
Alternative to if. |
switch var
case 0
dc.b 'var is 0'
case 1
dc.b 'var is 1'
elsecase
dc.b 'var is something else'
endcase |
|
rept x and endr |
rept x and endm |
Assembles code x number of times. Useful in combination with narg in macros. |
rept 3
dc.b 0 ; same as dc.b 0,0,0
endr |
while and endw |
while and endm |
Assembles code repeatedly while condition is met.equs does not work inside a while loop. |
var: = 0
while var<3
dc.b var ; same as dc.b 0,1,2
var: = var+1
endw |
do and until |
Assembles code repeatedly until condition is met. | var: = 0
do
dc.b var ; same as dc.b 0,1,2
var: = var+1
until var>2 |
|
end |
Stops assembly. Place at the end of the main ASM file. | ||
ifdef x |
True if x is defined. |
||
ifndef x |
True if x is undefined. |
||
ifused x |
True if x is referenced in the code (so far). |
||
ifnused x |
True if x is unreferenced in the code (so far). |
||
ifexist x |
True if file x exists. |
||
ifnexist x |
True if file x doesn't exist. |
||
ifb x,..,y |
True if listed parameters are all blank. | ||
ifnb x,..,y |
True if listed parameters aren't all blank. |
| ASM68K | AS | Purpose | Example |
|---|---|---|---|
macro and endm |
Defines a macro. Parameters can be named or left blank (in which case they are referenced by \1, \2 etc. |
writebyte: macro num
dc.b \num
endm
writebyte 5 ; same as dc.b 5 |
|
macros |
Single-line macro. endm not needed. |
writebyte: macros
dc.b \1 |
|
mexit |
exitm |
Exits macro prematurely. | |
\0 |
ATTRIBUTE |
Size parameter. Whatever is after the . when a macro is used, usually b, w or l but can be anything. |
writeany: macro
dc.\0 \1
endm
writeany.l 999 ; same as dc.l 999 |
\@ |
Underscore followed by the number of times the macro has been used. Useful for creating unique labels. | setvalue: macro
value\@: equ \1
endm
setvalue 5 ; same as value_1: equ 5 |
|
\# and \$ |
Value of variable output as a string. \# is decimal and \$ is hex. |
value: equ 5
string: equs "\#value" ; same as string: equs "5" |
|
\_ |
ALLARGS |
All parameters, including the commas. | |
\* |
Value of label where macro was used. * must be the first parameter, and \* must be defined. Label must be on the same line. |
readself: macro *
\*: equ *
self: equ \*
endm
readself ; same as self: equ * |
|
{INTLABEL} and __LABEL__ |
Value of label where macro was used. {INTLABEL} must be the last parameter. Label must be on the same line. |
readself: macro {INTLABEL}
self: equ __LABEL__
endm
readself ; same as self: equ * |
|
narg |
ARGCOUNT |
Number of parameters used in a macro. AS will include all named parameters, even if they aren't used. | nargout: macro
dc.b narg
endm
nargout 1,2,3,4 ; same as dc.b 4 |
shift |
shift |
Deletes the first parameter and moves the rest left. Useful in combination with narg. |
|
pushp and popp |
|||
purge |
Deletes a macro. | purge macroname |
|
! |
AS allows redefining any instruction with macros. ! uses the original unaltered instruction. |
move macro
endm
!move.b d0,d1 |
|
function |
Custom function. Last parameter is the expression, all parameters before that are the function's parameters. | times2: function x,x+x
dc.b times2(4) ; same as dc.b 8 |
| ASM68K | AS | Purpose | Example |
|---|---|---|---|
include |
Include an ASM file. | include "file.asm" |
|
incbin |
binclude |
Include a binary file. | incbin "file.bin"
incbin "file.bin",$10 ; start at address $10 in file
incbin "file.bin",$10,$20 ; start at $10, include only $20 bytes |
| ASM68K | AS | Purpose | Example |
|---|---|---|---|
ref(x) |
Returns true if label x has been previously encountered. |
if ref(label) ; false on first run, true on second
label: rts
endif |
|
def(x) |
Returns true if label x has been defined. |
label: equ 1
if def(label) ; true |
|
type(x) |
Returns info on label x as a word bitfield. |
||
strlen(x) |
strlen(x) |
Returns length of string x. |
if strlen("text")=4 ; true
label: equs "four"
if strlen(label)=4 ; true |
strcmp(x,y) |
Returns true if string x matches string y. Variables require quotes and backslash. |
label: equs "text"
if strcmp("\label","text") ; true |
|
instr(x,y) and instr(s,x,y) |
Returns position of substring y in string x (starts at 1). Returns 0 if not found. s specifies starting position. |
label: equs "string"
dc.b instr("\label","r") ; 3
dc.b instr(2,"\label","r") ; 3
dc.b instr(4,"\label","r") ; 0 |
|
substr |
Assigns substring to variable. Actually more like a macro than a function. Its parameters are start, end (both optional) and string. | label: equs "string"
sub1: substr 2,5,"\label" ; sub1 = trin
sub2: substr 2,,"\label" ; sub2 = tring
sub3: substr ,5,"\label" ; sub3 = strin
sub4: substr ,,"\label" ; sub4 = string |
|
bitcnt(x) |
Returns count of bits set in x. |
||
firstbit(x) |
Returns number of the lowest bit set in x, or -1 if not found. |
||
lastbit(x) |
Returns number of the highest bit set in x, or -1 if not found. |
||
bitpos(x) |
Returns number of the (only) bit set in x, or fails assembly if not found. |
||
sgn(x) |
Returns 0, 1 or -1 if x is 0, positive or negative respectively. |
||
abs(x) |
Returns absolute value of x. |
||
upstring(x) |
Returns uppercase equivalent of x. upstring("x") returns X. |
||
lowstring(x) |
Returns lowercase equivalent of x. |
||
substr(x,y,z) |
Returns substring of x, starting at position y and of length z. |
||
charfromstr(x,y) |
Returns the character in x at position y. |
||
strstr(x,y) |
Returns position of substring y in string x (starts at 0). Returns -1 if not found. Similar to ASM68K's instr(). |
||
val(x) |
Converts x from string to expression. |
dc.b val("1+1") ; same as dc.b 2 |
|
exprtype(x) |
Returns type of x — 0 for integer, 1 for floating (not relevant here) and 2 for string. Similar to ASM68K's type(). |
| ASM68K | AS | Purpose | Example |
|---|---|---|---|
opt |
Sets an option. + enables and option and - disables it. |
||
opt ae+ |
Enable automatic even before dc.w, dc.l and similar. |
||
opt an+ |
Enable alternative numbers. i.e. those in Z80 assembly (100h, 0Ah). | ||
opt c+ |
Enable case sensitivity. c- is default. |
||
opt d+ |
Descope local labels? d- is default. |
||
opt e+ |
Error text in command line output. | ||
opt lx |
Set local label prefix to x. @ is default. |
||
opt w+ |
Warning text in command line output. | ||
opt ws+ |
Allow whitespace in instructions (e.g. 1 + 2). ws- is default. |
||
opt op+ |
Optimise (pc) relative from long addressing if possible. op- is default. |
||
opt os+ |
Optimise branches if possible. os- is default. |
||
opt ow+ |
Optimise longwords to words if possible. ow- is default. |
||
opt oz+ |
Optimise 0(a0) to (a0). oz- is default. |
||
opt oaq+, osq+ and omq+ |
Optimise add, sub and move to addq, subq and moveq if possible. oaq-, osq- and omq- are default. |
||
pusho and popo |
Save and restore options, allowing for temporary options to be used. | ||
nolist and list |
Disable and enable list generation temporarily. | ||
inform x,y,z |
Outputs the error message y to command line. x can be 0 (show text only), 1 (text as warning), 2 (text as error) or 3 (stops assembly). y can contain %d (decimal), %h (hex) or %s (string) which are substituted by expression z. |
if value>max inform 3,"Value $%h is too high.",value endc | |
message x and warning x |
Outputs the message x to command line. |
||
error x and fatal x |
Outputs the message x to command line and stops assembly. |
||
fail |
Stops assembly. |