Tool z80asm input format - z88dk/z88dk GitHub Wiki

Input Files

z80asm reads text files in the syntax supported by the specific processor being assembled for (see -m option) and produces the corresponding object files.

An input file with a .o extension is assumed to be already in object file format and is just read by the linker. Any other extension is considered an assembly source file (conventionally .asm).

A project list file may be supplied in the command line prefixed by the at-sign (e.g. @project.lst). The list file contains one input file name per line, or another project list prefixed with an at-sign, which is opened recursively. Hash signs (#) and semi-colons (;) mat be used at the start of lines in the list files to include comments.

Both the command line and the list files support wild-cards to expand all the files that match the given pattern.
Note that the Operating System may do its own wildcard expansion and the pattern may need to be quoted in the command line.

A single star in a file name (*) expands to the list of all files/directories that match the complete pattern, where the star represents any sequence of characters. A double-star in a directory name (**) expands to the complete directory sub-tree, when searched recursively.

Input Lines

The assembler parses source files with any of the common end-of-line termination sequences (CR, LF or CR-LF). Each line starts with an optional label and can contain assembly directives (i.e. instructions to the assembler), assembly instructions (i.e. code to be translated into object code for the specific processor) or blanks and comments.

Differently to most other assemblers, white space is not significant, i.e. a label can be defined after white space, and an opcode can be written at column 1.

Continuation Lines

Lines ending with a backslash are logically continued on the next line. This allows breaking a long line, e.g.

ld a,\
1           ; -> 3e 01

Multiple Statements

Multiple statements can be written in a physical line by separating them with a backslash or a colon, e.g.

ld a, 1 \ ret   ; -> 3e 01 c9
ld a, 1 : ret   ; -> 3e 01 c9

Note: the colon is still accepted as a label suffix and as an operator in the ternary condition cond ? t : f.

Comments

Comments start with a semi-colon (;) and end at the end of the line.

Symbols

All symbols in the code (labels, variables, ...) are named with unique identifiers. Identifiers start with a letter or underscore (_), and can contain letters, underscores or digits. Identifiers are case-sensitive.

Labels

A label is defined at the start of a line by prefixing a symbol with a dot (.) or suffixing it with a colon (:), i.e. either .label or label:. The symbol may be used to refer to address in the object code.

Numbers

The assembler accepts numbers in decimal, hexadecimal, octal and binary. Different syntax is allowed to simplify porting of code written for other assemblers. Some of the prefix characters are also used as operators; in this case a space may be needed to signal the difference.

   ld a, %10     ; A = 2 (10 binary)
   ld a, 12 % 10 ; A = 2 (remainder of 12 divided by 10)

All expressions are computed as signed integers with the host platform's integer size (32-bit or 64-bit in the most common platforms).

Decimal numbers are a sequence of decimal digits (0..9), optionally followed by a d or D - all prefixes and suffixes are case-insensitive. Leading zeros are not significant - note the difference from C, where a leading zero means octal.

  ld a, 99
  ld a, 99d
  ld a, 99D

Floating Point numbers are a sequence of decimal digits including a decimal dot (0..9, .), optionally followed by an e and an exponent. They are allowed in the FLOAT directive that encodes them in the current floating point format in the object code.

Hexadecimal numbers are a sequence of hexadecimal digits (0..9 and A..F, case-insensitive), either prefixed or suffixed with an hexadecimal marker. If the marker is a suffix, and the number starts with a letter, then a leading zero has to be added.

  ld a, $FF
  ld a, 0xFF
  ld a, 0FFh

Binary numbers are a sequence of binary digits (0..1), either prefixed or suffixed with a binary marker.

  ld a, %11
  ld a, @11
  ld a, 0b11
  ld a, 11b

Binary numbers can be specified as bitmaps, with # as 1 and - as 0, using the binary prefix (@ or %) immediately followed by a double-quoted string of hashes and dashes.

  defb @"---##---"
  defb @"-##--##-"
  defb %"-##-----"
  defb %"-##-----"
  defb @"-##--##-"
  defb @"---##---"

Keywords

Processor registers (BC, DE, ...) and flags (NZ, Z, ...), and assembly ASMPC, representing the current assembly location, are reserved keywords. They cannot be used as identifiers, and are case-insensitive.

Directives and Opcodes

Assembler directives (ORG, INCLUDE, ...) and processor opcodes (NOP, LD, ...) are interpreted as directives or opcodes when appearing at the start of the statement or after a label definition, or as regular identifiers otherwise. The directives and opcodes are case-insensitive.

  jr: jr jr  ; silly example, jr is both a label and an opcode
             ; while correct code, it's confusing