Glass Z80 assembler
Copyright © 2013, Laurens Holst
Glass is a cross-platform assembler for the Z80 processor, written in Java 8.
Bug reports and feature requests go here.
Glass is BSD licensed, which means that you are free to use the software and source code in any way you wish as long as attribution is given to the original project and its author(s). For details, please consult the LICENSE file. To submit contributions, please contact the author.
To run Glass from the command line, use the following command.
java -jar glass.jar [OPTION] SOURCE [OBJECT] [SYMBOL]
Source specifies the source file, object the output file, and symbol a text file which will hold a list of symbols and their addresses in the output.
Note that Java 8 must be installed to run Glass.
To check your Java version, invoke the
java -version command.
The assembler syntax follows common style.
Lines are composed as follows:
label: mnemonic arguments ;comment
Note that the white space before the mnemonic is significant; otherwise, it will be interpreted as a label.
All identifiers are case-sensitive. Mnemonics of built-in instructions, directives, registers, flags and annotations are recognised in lowercase and uppercase, but can not be mixed case.
Labels and other identifiers follow the following grammar:
identifier = id_start_char id_char* id_start_char = [a-z] | [A-Z] | _ | . | ? | @ id_char = id_start_char | [0-9] | ' | $
The colon after a label is optional. If a label has no colon, it can not have any leading white space, it must start at column 0.
Standard z80 instruction syntax is used:
ld a,(ix + 10)
Parentheses are used to indicate indirection.
For a complete description of the Z80 instruction set, see the official Zilog documentation: http://www.zilog.com/docs/z80/um0080.pdf
In addition to the documented Z80 instructions, the variations using the undocumented
iylindex registers are supported, as well as the semi-documented
For register jumps,
jp (hl)etc., the parentheses are optional.
R800 multiplication instructions.
Defines a byte or a sequence of bytes.
Defines a word or a sequence of words.
Define double word:
Defines a double word or a sequence of double words.
Defines space for a number of bytes. The first argument indicates the number of bytes, the optional second argument specifies the fill value (default 0).
The first argument can be annotated with
virtual, in which case the address counter will be incremented accordingly, but no object is actually generated in the output. If the virtual annotation is given, you can not specify a fill value.
Changes the address location counter and sets a new origin for subsequent statements.
Assigns a constant value to a symbol.
JIFFY: equ 0FC9EH
Includes another source file. The current working directory is searched, as well as any include paths specified on the command line.
Optionally you can specify a
onceannotation to prevent a file from being included more than once. However it is not recommended to use unless needed.
INCLUDE ONCE "math.asm"
Includes binary data from a file. The current working directory is searched, as well as any include paths specified on the command line.
Optionally you can specify a start position and length:
Defines a macro instruction, composed of all the instructions that follow until the
endmdirective is encountered. The definition’s arguments specify the parameters which are passed when the macro is invoked.
ALIGN: MACRO ?boundary ds ?boundary - 1 - ($ + ?boundary - 1) % ?boundary ENDM ALIGN 100H
All symbols defined in a macro block are local. Symbols in macro instances can be referenced by using the
.operator. Symbols in macro definitions can also be referenced; the contents are assembled on address 0, effectively turning the inner symbols into offsets. This is useful for specifying structures and indexing.
Default values for macro arguments can be specified with
ALIGN: MACRO ?boundary = 100H
Repeats a section of code a number of times. The end of the section is marked with the
endmdirective. The first argument is mandatory and specifies the number of repeats. The second argument specifies a counter parameter, the third the initial value for the counter (default: 0), and the fourth argument specifies the counter increment (default: 1).
REPT 10, ?counter, 0, 2 ld bc,(table + ?counter) REPT 3 add hl,bc ENDM ENDM
All symbols defined in a repeat block are local. If a repeat is labeled, the inner repeat scopes can be accessed by index, e.g.:
Repeats a section of code for each of the arguments specified. The end of the section is marked with the
endmdirective. The first argument is mandatory and specifies the parameter the current repetition’s value is passed to. The remaining arguments are passed one by one as the section is repeated.
IRP ?value, 1, 2, 4, 8, 16, 32, 64, 128 or ?value ENDM
All symbols defined in a indefinite repeat block are local. If a repeat is labeled, the inner repeat scopes can be accessed by index, e.g.:
Defines a section of code as a procedure. Currently mostly serves to establish a local scope.
shift5: PROC ld b,5 jp shiftl.loop ENDP shiftl: PROC ld b,1 loop: add a,a djnz loop ret ENDP
All symbols defined in a procedure block are local. Symbols in inner scopes can be referenced by using the
Conditionally assembles a section of code, or an optional alternative section. The end of the section is either marked with
endif, or with
elsein which case an alternative will follow up to the
endif. The argument is evaluated as an integer, and if the result is nonzero (true) the first section is assembled, and if the result is zero (false) the alternative is assembled if one is provided.
PAD: MACRO ?address IF $ > ?address ERROR "Padding address exceeded." ELSE ds ?address - $ ENDIF ENDM
Generates an error and aborts the compilation. Optionally a message can be specified.
ERROR "Limit exceeded."
Generates a warning. Optionally a message can be specified.
WARNING "Nearly out of space."
Defines a section of code or data that will be assembled inside the space of a ds statement. This allows you to have nonadjacent code or data sections and group them into separate regions, such as ROM and RAM pages. The mandatory argument references the DS statement that is the target of the section.
org 4000H ROM_PAGE1: ds 4000H ROM_PAGE2: ds 4000H RAM: ds VIRTUAL 3000H SECTION ROM_PAGE1 SetValue: ld (value),a ret SECTION RAM value: db 0 ENDS ENDS
Strings support the following escape sequences:
\"(double quotation mark)
\'(single quotation mark)
Numeric escape sequences are not supported. In stead, you can insert them using
the comma operator:
"abc", 0FFH, "def".
The character set used to read files is ISO-8859-1, this maps the file’s bytes 1:1 to the Unicode code points used internally so the object code output matches the input file bytes verbatim.
The assembler uses 32-bit integer math internally. When a 8-bit or 16-bit value is generated, the excessive bits are usually truncated. Except for addresses, used in jumps, calls and indirect loads, they generate an error. Index and relative jump offsets are also checked to be in their allowed range.
a * b
a / b
a % b
a + b
a - b
- Shift left:
a << b
- Shift right:
a >> b
- Less than:
a < b
- Less or equal:
a <= b
- Greater than:
a > b
- Greater or equal:
a >= b
a = b
- Not equal:
a != b
- Bitwise and:
a & b
- Bitwise xor:
a ^ b
- Bitwise or:
a | b
- Logical and:
a && b
- Logical or:
a || b
- Ternary if:
a ? b : c
Logical operators use integers to represent true / false values. 0 means false, any other value means true. They return -1 for true values.
Logical and / or apply short-circuit evaluation and evaluate to the last evaluated value, so they can also be used similar to a ternary operator.
Expressions can span multiple lines when they’re incomplete at the line ends.