acme/docs/AllPOs.txt

                                 ACME

         ...the ACME Crossassembler for Multiple Environments

                        --- pseudo opcodes ---


This is a list of all the pseudo opcodes currently implemented.
Stuff in square brackets is optional, stuff followed by "*" may be
given more than once. This list is not sorted alphabetically, the
pseudo opcodes are grouped together according to their usage.


----------------------------------------------------------------------
Section:   How to insert values
----------------------------------------------------------------------

Call:		!8 EXPRESSION [, EXPRESSION]*
Purpose:	Insert 8-bit values.
Parameters:	EXPRESSION: Any formula the value parser accepts.
Aliases:	"!08", "!by", "!byte"
Examples:	!08 127, label, -128	; output some values
		!by 14, $3d, %0110, &304, <*, "c"
		!byte 3 - 4, label1 XOR label2, 2 ^ tz, (3+4)*7


Call:		!16 EXPRESSION [, EXPRESSION]*
Purpose:	Insert 16-bit values.
Parameters:	EXPRESSION: Any formula the value parser accepts.
Aliases:	"!wo", "!word"
Examples:	!16 65535, label, -32768	; output some values
		!wo 14, $4f35, %100101010010110, &36304, *, "c"
		!word 3000 - 4, a1 AND a2, 2 ^ tz, (3+4)*70, l1 & .j2


Call:		!24 EXPRESSION [, EXPRESSION]*
Purpose:	Insert 24-bit values.
Parameters:	EXPRESSION: Any formula the value parser accepts.
Examples:	!24 16777215, label, -8388608, 14, $6a4f35
		!24 %10010110100101010010110, &47336304, *, "c"
		!24 300000 - 4, a1 AND a2, 2 ^ tz, (3+4)*70, l1 & .j2


Call:		!32 EXPRESSION [, EXPRESSION]*
Purpose:	Insert 32-bit values.
Parameters:	EXPRESSION: Any formula the value parser accepts.
Examples:	!32 $7fffffff, label, -$80000000, 14, $46a4f35
		!32 %1001011010010101001011010010, &4733630435, *, "c"
		!32 300000 - 4, a AND a2, 2 ^ tz, (3+4)*70, l1 & .j2


Call:		!fill AMOUNT [, VALUE]
Purpose:	Fill amount of memory with value.
Parameters:	AMOUNT: Any formula the value parser accepts, but it
		must be solvable even in the first pass.
		VALUE: Any formula the value parser accepts. If
		omitted, a default value is used (currently zero).
Aliases:	"!fi"
Examples:	!fi 256, $ff	; reserve 256 bytes
		!fill 2		; reserve two bytes


Call:		!align ANDVALUE, EQUALVALUE [, FILLVALUE]
Purpose:	Fill memory until a matching address is reached. ACME
		outputs FILLVALUE until "program counter AND ANDVALUE"
		equals EQUALVALUE.
Parameters:	ANDVALUE: Any formula the value parser accepts, but it
		must be solvable even in the first pass.
		EQUALVALUE: Any formula the value parser accepts, but
		it must be solvable even in the first pass.
		FILLVALUE: Any formula the value parser accepts. If it
		is omitted, a default value is used (currently 234,
		that's the 6502 CPU's NOP command).
Examples:	; eliminate the 6502's JMP()-Bug:
		!align 1, 0	; wait for even address
	Label	!word Pointer

		; align code to page border for speed increase
		!align 255, 0


----------------------------------------------------------------------
Section:   How to insert text strings
----------------------------------------------------------------------

Call:		!convtab KEYWORD [ { BLOCK } ]
or:		!convtab FILENAME [ { BLOCK } ]
Purpose:	Choose text conversion table.
Parameters:	KEYWORD: Name of conversion table. Valid names are:
			pet	converts to PetSCII
			raw	doesn't convert at all
			scr	converts to C64 screencode
		FILENAME: File name of conversion table, given in
		"..." quoting (load from current directory) or in
		<...> quoting (load from library). The file must hold
		exactly 256 bytes.
		BLOCK: A block of assembler statements
		Before encountering this PO, ACME defaults to "raw".
		This PO supersedes the now deprecated "!cbm".
Aliases:	"!ct"
Examples:	!convtab raw
		!text "Test"	; outputs $54 $65 $73 $74
		!ct pet
		!tx "Test"	; outputs $d4 $45 $53 $54
		!ct scr {
			!tx "Test"	; outputs $54 $05 $13 $14
			!ct "my_own_table_file"
			!tx "abcdefg"	; whatever... :)
		}
		!tx "Test"	; outputs $d4 $45 $53 $54 again
Hint: If you don't want to fiddle with a hex editor to create a
conversion table file, try using ACME:
		!to "asc2pet.ct", plain	; no load address
		*=0			; pc = table index
		; first create "as-is" table
		!for i, 256 {!byte i-1}
		; now exchange upper and lower case characters
		*=65
		!for i, 91-65 {!byte *+128}
		*=97
		!for i, 123-97 {!byte *-32}
The resulting file can be used as a conversion table to convert to
PetSCII (which is useless, because ACME can do so anyway. But you get
the idea).


Call:		!text STRING_VALUE [, STRING_VALUE]*
Purpose:	Output the given string(s) using the current
		conversion table.
Parameters:	STRING_VALUE: Can be either a string given in double
		quotes or any formula the value parser accepts.
		Please note that formula results won't be converted,
		but single characters involved in calculations will.
Aliases:	"!tx"
Examples:	!text "Loading...", Char_NewLine, "Filename:", 0
		!tx "Offset character is ", offset-1+'a', 0


Call:		!pet STRING_VALUE [, STRING_VALUE]*
Purpose:	Output the given string(s) using the PetSCII
		conversion table (This means to exchange the upper-
		and lowercase characters; useful for C64 programs).
Parameters:	STRING_VALUE: Can be either a string given in double
		quotes or any formula the value parser accepts.
		Please note that formula results won't be converted,
		but single characters involved in calculations will.
Examples:	!pet "Loading...", Char_NewLine, "Filename:", 0
		!pet "Offset character is ", offset-1+'a', 0


Call:		!raw STRING_VALUE [, STRING_VALUE]*
Purpose:	Output the given string(s) without any conversion at
		all.
Parameters:	STRING_VALUE: Can be either a string given in double
		quotes or any formula the value parser accepts.
Examples:	!raw "Loading...", Char_NewLine, "Filename:", 0
		!raw "Offset character is ", offset-1+'a', 0


Call:		!scr STRING_VALUE [, STRING_VALUE]*
Purpose:	Output the given string(s) using the C64 screen code
		conversion table (useful for C64 programs, as you will
		have guessed).
Parameters:	STRING_VALUE: Can be either a string given in double
		quotes or any formula the value parser accepts.
		Please note that formula results won't be converted,
		but single characters involved in calculations will.
Examples:	!scr "Loading...", Char_NewLine, "Filename:", 0
		!scr "Offset character is ", offset-1+'a', 0


Call:		!scrxor XOR_VALUE, STRING_VALUE [, STRING_VALUE]*
Purpose:	Output the given string(s) using the C64 screen code
		conversion table and exclusive-OR-ing the results with
		the given value (useful for C64 programs when inverse
		video is needed, or EBC mode, etc.).
Parameters:	XOR_VALUE: Any formula the value parser accepts.
		STRING_VALUE: Can be either a string given in double
		quotes or any formula the value parser accepts.
		Please note that formula results will be neither
		converted nor exclusive-OR-d.
		Single characters involved in calculations will be
		converted, but not exclusive-OR-d.
Examples:	!scrxor $80, "Loading..."
		!scrxor $a0, "Offset char is ", (offset-1+'a') XOR $a0


----------------------------------------------------------------------
Section:   File stuff
----------------------------------------------------------------------

Call:		!to FILENAME, FILEFORMAT
Purpose:	Define the output file name and file type. If this
		opcode isn't used, ACME still fully processes the
		source code - as the resulting binary isn't stored,
		this only serves to check for errors. Instead of using
		this pseudo opcode, you can also use the command line
		options "--outfile" and "--format".
Parameters:	FILENAME: A file name given in "..." quoting.
		FILEFORMAT: Name of file format. Valid names are:
			cbm	with load address (Commodore format)
			plain	without load address
			apple	with load address and length (Apple II)
		If FILEFORMAT is omitted, ACME gives a warning and
		then defaults to "cbm" (this can be changed using the
		command line option "--format").
Examples:	!to "eprom.p", plain	; don't add a load address
		!to "demo.o", cbm	; add c64-style load address


Call:		!source FILENAME
Purpose:	Assemble another source code file. After having
		processed the new file, ACME continues processing the
		old one.
Parameters:	FILENAME: A file name given in "..." quoting (load
		from current directory) or in <...> quoting (load from
		library).
Aliases:	"!src"
Examples:	!source <6502/std.a>	; Read library file
		!src "Macros.a"		; Read file from current dir


Call:		!binary FILENAME [, [SIZE] [, [SKIP]]]
Purpose:	Insert binary file directly into output file.
Parameters:	FILENAME: A file name given in "..." quoting (load
		from current directory) or in <...> quoting (load from
		library).
		SIZE: Any formula the value parser accepts, but it
		must be solvable even in the first pass. If SIZE is
		given, it is used: If the file is longer, only SIZE
		bytes are read; if it is shorter, ACME will use
		padding until SIZE is reached. If SIZE is omitted,
		ACME will include the file until EOF.
		SKIP: Any formula the value parser accepts. If SKIP is
		omitted, it defaults to zero. ACME will start loading
		the file from file offset SKIP. So C64 coders wanting
		to include C64 files without their load addresses
		should use a SKIP value of 2.
Aliases:	"!bin"
Examples:	!binary <Own/menudata.b>	; insert library file
		!bin "asc2pet.b", 256, 2	; insert 256 bytes
						; from file offset 2.
		!bin "table", 2, 9	; insert 2 bytes from offset 9
		!bin "list",, 9		; insert from offset 9 to EOF


----------------------------------------------------------------------
Section:   Labels
----------------------------------------------------------------------

Call:		!zone [TITLE] [ { BLOCK } ]
Purpose:	Switch to new zone of local labels. Zones can either
		be nested or used sequentially.
Parameters:	TITLE: May consist of letters and digits. Its only
		purpose is to be displayed in error messages, so it'll
		be omitted in most cases.
		BLOCK: A block of assembler statements
		If no block is given, the previous zone is terminated
		and the new zone is started.
		If a block is given, the old zone continues after the
		block.
Aliases:	"!zn"
Examples:	.backgroundcolor = 0	; some local label
		!zone File_IO		; new zone begins here
		.backgroundcolor = 1	; so this is a different label
		!zn LinkedList_Init
		.backgroundcolor = 2
		!zone LinkedList {	; start of nested zone
			; imagine some code here...
			!zone LinkedList_Init
			; imagine some more code here...
			!zone LinkedList_Body {
				; imagine yet some more code here...
				!zone LinkedList_SecondPart
				; imagine still some more code here...
			}
			!zone LinkedList_End
			; you know what to imagine here...
		}
		.backgroundcolor = 3	; => "Label already defined."


Call:		!sl FILENAME
Purpose:	Save all the global labels to the given file after the
		assembly is finished. This table could be loaded
		during another assembly session using the "!source"
		pseudo opcode.
Parameters:	FILENAME: A file name given in "..." quoting.
Examples:	!sl "Labels.a"	; produce label dump after assembly
		!sl "global"	; produce label dump after assembly


----------------------------------------------------------------------
Section:   Flow control
----------------------------------------------------------------------

Call:		!if CONDITION { BLOCK } [ else { BLOCK } ]
Purpose:	Conditional assembly. If the given condition is true,
		the first block of statements will be parsed;
		if it isn't, the second block will be parsed instead
		(if present).
Parameters:	CONDITION: Any formula the value parser accepts, but
		it must be solvable even in the first pass.
		BLOCK: A block of assembler statements.
Examples:	!text "Black", 0	; Choose wording according to
		!if country = uk {	; content of "country" label.
			!text "Grey"
		} else {
			!text "Gray"
		}
		!byte 0
		!text "White", 0

		; Insert debug commands if label "debug" is not zero:
		!if debug { lda #"z":jsr char_output }


Call:		!ifdef LABEL { BLOCK } [ else { BLOCK } ]
or:		!ifdef LABEL STATEMENT
Call:		!ifndef LABEL { BLOCK } [ else { BLOCK } ]
or:		!ifndef LABEL STATEMENT
Purpose:	Conditional assembly, depending on whether a label is
		already defined or not.
		With "ifdef", if the label is defined, the first block
		of statements will be parsed; if it isn't, the second
		block will be parsed instead (if present).
		With "ifndef", it's the other way around: If the label
		isn't defined, the first block of statements will be
		parsed; if it is defined, the second block will be
		parsed instead (if present).
		CAUTION: These opcodes were added to speed up parsing
		of library files (see example below). They can be used
		to tell passes apart, therefore only use them in your
		own files if you're sure you *really* know what you
		are doing - using them in the wrong way will result in
		loads of error messages.
Parameters:	LABEL: Any valid label name.
		BLOCK: A block of assembler statements.
		STATEMENT: Any assembler statement.
Examples:	; this was taken from <6502/std.a>:
		!ifdef Lib_6502_std_a !eof	; in later passes,
		Lib_6502_std_a = 1		; skip this file.
		; During the first pass, the label is not defined,
		; therefore the file will get parsed. During all
		; further passes, the label is already defined,
		; therefore the file will be skipped.

		; if the following code gets included several times,
		; only assemble it at the first location:
		!ifndef my_label {my_label} ; only define if undefined
		!if *=my_label {
			; imagine some code here...
			; this block will only be assembled at the
			; first location where it is included. all
			; further instances will be skipped.
		}


Call:		!for LABEL, TIMES { BLOCK }
Purpose:	Looping assembly. The block of statements will be
		parsed TIMES times. For a more flexible possibility,
		have a look at "!do" below.
Parameters:	LABEL: Any valid label name. The label's value will
		show the number of the current loop cycle:
		In the first cycle it will have the value 1, in the
		last cycle it will have the value TIMES.
		TIMES: Any formula the value parser accepts, but it
		must be solvable even in the first pass. Negative
		values are forbidden, zero causes the block to be
		skipped.
		BLOCK: A block of assembler statements.
		Please note that it is impossible to change the number
		of loop cycles "inside" the loop by fiddling with the
		counter (using the "!set" pseudo opcode): The "!for"
		routine keeps its own copy of the counter value and
		only sets the label value, it never reads it back.
		This was done to eliminate a possibility to hang ACME.
Examples:	; conversion table: integer to BCD
	int2BCD	!for Outer, 10 {
			!for Inner, 10 {
				!byte ((Outer-1) << 4) OR (Inner-1)
			}
		}
		!fill 156, $ff	; values above 99 give 255 (invalid)

		; conversion table: BCD to integer
	BCD2int	!for Outer, 10 {
			!for Inner, 10 {
				!byte 10 * (Outer-1) + (Inner-1)
			}
			!fill 6, $ff	; invalid BCD values give 255
		}
		!fill 96, $ff		; invalid BCD values give 255


Call:		!set LABEL = VALUE
Purpose:	Assign given value to label even if the label already
		has a different value. Needed for loop counters when
		using "!do", for example. Only use this opcode for
		something else if you're sure you *really* know what
		you are doing... :)
Parameters:	LABEL: Any valid label name.
		VALUE: Any formula the value parser accepts.
Example:	see "!do" below


Call:		!do [KEYWORD CONDITION] { BLOCK } [KEYWORD CONDITION]
Purpose:	Looping assembly. The block of statements can be
		parsed several times, depending on the given
		condition(s).
		Conditions may be placed before or after the block (or
		even at both places), they are then parsed in every
		repetition before or after the block respectively. If
		there is a condition before the block and it isn't
		met when first checked, the block will be skipped.
Parameters:	KEYWORD: Either "until" or "while" (without quotes).
		CONDITION: Any formula the value parser accepts, but
		it must be solvable even in the first pass.
		BLOCK: A block of assembler statements.
Examples:	; a loop with conditions at both start and end
		!set a = 0			; init loop counter
		!do while loop_flag = TRUE {
			lda #a
			sta label+a
			!set a = a + 1
		} until a > 6

		; a loop with a condition at the start
		!do while * < $c000 { nop }

		; a loop with a condition at the end
		!do { !wo * + base } while * < base + 345

		; a never ending loop - this will cause an error
		!do while 3 < 4 { nop } until 3 = 4

		; an empty loop - this will hang ACME
		!do until 3 = 4 {     } while 3 < 4


Call:		!endoffile
Purpose:	Stop processing the current source file. Using this
		pseudo opcode you can add explanatory text inside your
		source file without having to comment out every single
		line of it.
Aliases:	"!eof"
Example:	rts	; some assembler mnemonic
		!eof
		Though this text isn't preceded by a semicolon, it is
		treated as if it were a comment. In fact, ACME doesn't
		even parse this anymore - the file gets closed when
		"!eof" is reached.


Call:		!warn STRING_VALUE
Purpose:	Show a warning during assembly.
Parameters:	STRING_VALUE: A string given in double quotes.
Example:	!if * > $a000 {
			!warn "Program reached ROM area."
		}


Call:		!error STRING_VALUE
Purpose:	Generate an error during assembly (therefore, no
		output file will be generated).
Parameters:	STRING_VALUE: A string given in double quotes.
Example:	rts	; end of some function
	start	!source "colors.a"
	end	!if end-start > 256 {
			!error "Color strings exceed 256 chars!"
		}


Call:		!serious STRING_VALUE
Purpose:	Generate a serious error, immediately stopping
		assembly.
Parameters:	STRING_VALUE: A string given in double quotes.
Example:	!source "part1.a"	; sets part1_version
		!source "part2.a"	; sets part2_version
		!if part1_version != part2_version {
			!serious "part1.a and part2.a don't match!"
		}


----------------------------------------------------------------------
Section:   Macro usage
----------------------------------------------------------------------

Call:		!macro TITLE [[~]LABEL [, [~]LABEL]*] { BLOCK }
Purpose:	Define a macro.
Parameters:	TITLE: The macro's desired name (same rules as for
		label names). If the title's first character is a dot
		("."), the macro will be local (though why anyone
		could want this is beyond me).
		LABEL: The desired name for the parameter value at
		call time. Normally, these parameter labels should be
		local (first character a dot), as different macro
		calls will almost for sure have different parameter
		values.
		If you prefix LABEL with a '~' character, it will be
		called by reference, not by value: Changing the value
		inside the macro will result in the "outer" label to
		be changed as well.
		BLOCK: A block of assembler statements.
Examples:	; far branch, as defined in <6502/std.a>
		!macro bne .target {
			beq * + 5
			jmp .target
		}

		; increase 16-bit counters
		!macro dinc .target {
			inc .target
			bne +	; "bne * + 5" would not work in zp
			inc .target + 1
		+
		}
		; Yes, anonymous label references can be used with
		; macros (unlike several other assemblers). That's
		; because ACME's macros are implemented more like
		; real functions.

		; load A and X
		!macro ldax .target {
			lda .target
			ldx .target + 1
		}

		; store A and X
		!macro stax .target {
			sta .target
			stx .target + 1
		}

		; use call-by-reference for return value
		!macro reserve ~.address, .amount {
			.address = external_pc
			!set external_pc = external_pc + .amount
		}

		; define a pixel row of a C64 hardware sprite
		!macro SpriteLine .v {
			!by .v>>16, (.v>>8)&255, .v&255
		}


Call:		+TITLE [ARGUMENT [, ARGUMENT]*]
Purpose:	Call a macro, using the given parameter values.
Parameters:	TITLE: The macro's name as given in its definition.
		ARGUMENT: This is either any formula the value parser
		accepts, or (new in release 0.86) a '~' character
		followed by a label name. The '~'-prefix indicates
		call-by-reference semantics, which means that when the
		macro changes the label's value, the caller's label's
		value will change as well.
Examples:	inc label
		bne mark	; "near" branch
		inc label2
		+bne mark2	; "far" branch

		inc $fa		; increase  8-bit counter
		+dinc $fb	; increase 16-bit counter

		ldy label	; get byte
		+ldax label2	; get two bytes

		; using macro calls in a macro definition
		!macro cp16 .source, .target {
			+ldax .source
			+stax .target
		}

		; use call-by-reference for return value
		!set external_pc = $0400
		+reserve ~.line_buffer, 80
		+reserve ~.in_buffer, 256
		+reserve ~.out_buffer, 256
		+reserve ~.byte_var, 1

		; define a C64 hardware sprite
		;            765432107654321076543210
		+SpriteLine %........................
		+SpriteLine %.#......................
		+SpriteLine %.##.....................
		+SpriteLine %.###....................
		+SpriteLine %.####...................
		+SpriteLine %.#####..................
		+SpriteLine %.######.................
		+SpriteLine %.#######................
		+SpriteLine %.########...............
		+SpriteLine %.#########..............
		+SpriteLine %.########...............
		+SpriteLine %.######.................
		+SpriteLine %.######.................
		+SpriteLine %.##..##.................
		+SpriteLine %.#....##................
		+SpriteLine %......##................
		+SpriteLine %.......##...............
		+SpriteLine %.......##...............
		+SpriteLine %........##..............
		+SpriteLine %........##..............
		+SpriteLine %........................
		!byte 0	; pad to 64-byte block

Since release 0.86, different macros are allowed to have the same name
as long as their parameter lists differ in size (number of arguments)
or type (call-by-value vs. call-by-reference). So
		!macro process_bytes b1,b2 {...whatever...}
		!macro process_bytes b1,b2,b3 {...whatever...}
		!macro process_bytes b1,b2,~b3 {...whatever...}
can *all* be used at the same time without any name clash.


----------------------------------------------------------------------
Section:   Segment assembly
----------------------------------------------------------------------

Call:		*= EXPRESSION [,MODIFIER]*
Purpose:	Set program counter to given value and start new
		segment. This opcode must be given at least once
		(or the command line option "--setpc" must be used).
		If segments overlap each other, warnings will be
		issued. Because some people do this overlapping
		on purpose, the warnings can be suppressed using
		modifier keywords.
		Future versions of ACME may issue errors instead of
		warnings.
Parameters:	EXPRESSION: Any formula the value parser accepts, but
		it must be solvable even in the first pass.
		MODIFIER: "overlay" or "invisible" (without quotes):
		"overlay" suppresses the warning "Segment starts
		inside another one, overwriting it".
		"invisible" makes the new segment invisible, so that
		_other_ segments will never raise the warning "Segment
		reached another one, overwriting it".
Examples:	!to "TinyDemo", cbm	; define output file + format
		*= $0801		; start at C64 BASIC start
		!src "basicmacros.a"	; include macro definitions
		+basic_header		; call program header macro
		!src "main.a"		; include main program
		*= $1000		; jump to new segment
		!bin "music.b"		; load music to $1000
		*= $8000		; jump to new segment
		!bin "pic.b"		; load graphics to $8000
		*= $8010, overlay, invisible	; go back and patch
				; the graphics, suppressing warnings
		; After assembly, ACME will save everything from $0801
		; up to the highest address written to. The resulting
		; file will contain some big unused areas (zero'd),
		; but demos will get compressed anyway... :)


Call:		!initmem EXPRESSION
Purpose:	Define "unchanged" memory. ACME will fill its output
		buffer completely with the given value before storing
		the assembled code. So gaps between segments will
		contain the desired byte when writing the output file.
		Instead of using this pseudo opcode, you can also use
		the "--initmem" command line option. If neither is
		used, the buffer is cleared.
Parameters:	EXPRESSION: Any formula the value parser accepts, but
		it must be solvable even in the first pass (because
		this opcode will be ignored in all later passes).
Examples:	!to "TinyDemo", cbm	; define output file + format
		!initmem $ea		; default memory content $ea.
		*= $0801		; start at C64 BASIC start
		!src "basicmacros.a"	; include macro definitions
		+basic_header		; call program header macro
		!src "main.a"		; include main program
		*= $1000		; jump to new segment
		!bin "music.b"		; load music to $1000
		*= $8000		; jump to new segment
		!bin "pic.b"		; load graphics to $8000
		*= $8010, overlay, invisible	; go back and patch
				; the graphics, suppressing warnings
		; This is the same example as before, but now the big
		; unused areas will contain the value $ea instead of
		; zero.

		!initmem $ff	; Default memory content is now $ff.
		; Useful if you want to store your code in an EPROM.


----------------------------------------------------------------------
Section:   Offset assembly
----------------------------------------------------------------------

Call:		!pseudopc EXPRESSION [ { BLOCK } ]
Purpose:	Assemble code as if the program counter had the given
		value, effectively producing a program that has to be
		copied to a different address space before being run.
		After having processed the block of statements with
		the new program counter, the updated (!) old program
		counter is used again.
		Thanks to the block syntax, offset assembly can now be
		nested. Then the old program counter would not
		necessarily be the *real* program counter, but could
		be a pseudopc as well. ;)
Parameters:	EXPRESSION: Any formula the value parser accepts, but
		it must be solvable even in the first pass.
		BLOCK: A block of assembler statements.
Examples:	ldx #.shifted_end-.shifted_start
	-		lda .shifted_start-1,x
			sta .target-1,x
			dex
			bne -
		jmp .target
	.shifted_start
		!pseudopc $0400 {
	.target	; imagine some code here...
		; it should be copied to $0400 and executed *there*
		}
	.shifted_end


----------------------------------------------------------------------
Section:   CPU support pseudo opcodes (especially 65816 support)
----------------------------------------------------------------------

Call:		!cpu KEYWORD [ { BLOCK } ]
Purpose:	Select the processor to produce code for. If this PO
		isn't used, ACME defaults to the 6502 CPU (or to the
		one selected by the "--cpu" command line option).
		ACME will give errors if you try to assemble commands
		the chosen CPU does not have. You can change the
		chosen CPU at any time. When used with block syntax,
		the previously chosen CPU value is restored
		afterwards.
Parameters:	KEYWORD: Currently valid keywords are:
		6502	allows official mnemonics and addressing modes
		6510	adds mnemonics for some undocumented opcodes
			(but includes all the official 6502 stuff)
		65c02	allows official 65c02 stuff (includes 6502)
		65816	allows official 65816 stuff (includes 65c02)
		BLOCK: A block of assembler statements.
Examples:	!if cputype = $65c02 {
			!cpu 65c02 {	; temporarily allow 65c02 stuff
				stz .todelete
			}
		} else {
			pha
			lda #0
			sta .todelete
			pla
		}
		rts
		!cpu 65816	; allow 65816 commands from here on


Call:		!al [ { BLOCK } ]
Purpose:	Assume long (16 bits) accumulator. Only allowed when
		producing code for the 65816 CPU. When used with block
		syntax, the previous configuration is restored
		afterwards.


Call:		!as [ { BLOCK } ]
Purpose:	Assume short (8 bits) accumulator. Only needed when
		producing code for the 65816 CPU. When used with block
		syntax, the previous configuration is restored
		afterwards. Short accumulator is the default in every
		pass.


Call:		!rl [ { BLOCK } ]
Purpose:	Assume long (16 bits) index registers. Only allowed
		when producing code for the 65816 CPU. When used with
		block syntax, the previous configuration is restored
		afterwards.


Call:		!rs [ { BLOCK } ]
Purpose:	Assume short (8 bits) index registers. Only needed
		when producing code for the 65816 CPU. When used with
		block syntax, the previous configuration is restored
		afterwards. Short registers are the default in every
		pass.


----------------------------------------------------------------------
Section:   Deprecated pseudo opcodes (they still work at the moment)
----------------------------------------------------------------------

Call:		!cbm
Purpose:	Use PetSCII as the text conversion table. Now
		superseded by the "!convtab" pseudo opcode.
Old usage:	!cbm		; gives "use !ct pet instead" warning
Now use:	!convtab pet	; does the same without warning


Call:		!subzone [TITLE] { BLOCK }
Purpose:	Allows nesting of zones. Now superseded by "!zone"
		because that allows nesting as well.
Parameters:	TITLE: May consist of letters and digits. Its only
		purpose is to be displayed in error messages, so it'll
		be omitted in most cases.
		BLOCK: A block of assembler statements.
Aliases:	"!sz"
Old usage:	!subzone graphics {
			!source "graphics.a"
		}
Now use:	!zone graphics {
			!source "graphics.a"
		}


Call:		!realpc
Purpose:	Restore the program counter to its real value,
		therefore finishing offset assembly. Because
		"!pseudopc" now knows block syntax and can be nested,
		there's no reason to use "!realpc" any more.
Old usage:	!pseudopc $0400
		; imagine some code here...
		!realpc
Now use:	!pseudopc $0400 {
			; imagine some code here...
		}