Tool z80asm directives - z88dk/z88dk GitHub Wiki

Directives

z80asm accepts the following assembly directives.

ALIGN expression[, filler]

The first ALIGN statement in a section tells the linker to reserve space before the start of the section so that the section start address is a multiple of the constant expression.

A subsequent ALIGN statement is translated into DEFS.

ASSERT expression

Evaluate the constant expression and abort assembly with an assertion failure error if the expression is false.

.ASSUME ADL=0/1

Used in ez80/ez80_z80 machine to change the ADL mode. The ADL mode influences how some opcodes are coded (for 16 or 24 bit addresses).

BINARY|INCBIN "filename"

Loads a binary file at the current location in the object file.

CALL_OZ expression

Calls the Z88 operating system. The expression is a 16-bit expression and must evaluate to a constant. This is assembled as follows:

RST $20  
DEFB x ; 8-bit parameter

RST $20  
DEFW x ; 16-bit parameter

CALL_PKG expression

Calls the Z88 operating system. The expression is a 16-bit expression and must evaluate to a constant and be different from zero. This is assembled as follows:

RST $08  
DEFW expression

CU.WAIT ver, hor

Calls the z80n copper unit, see Copper unit.

Encoded as: (big-endian)

0x8000 + (hor << 9) + ver

where:

0 <= ver <= 311, 0 <= hor <= 55

CU.MOVE reg, val

Calls the z80n copper unit, see Copper unit.

Encoded as: (big-endian)

(reg << 8) + val

where:

0 <= reg <= 127, 0 <= val <= 255

CU.STOP

Calls the z80n copper unit, see Copper unit.

Encoded as:

0xFFFF

CU.NOP

Calls the z80n copper unit, see Copper unit.

Encoded as:

0x0000

DEFB|DB|DEFM|DM|BYTE expression|"string"[,...]

Stores a sequence of bytes at the current location.

Expressions may be computed at the link phase, i.e. they may refer to external or address symbols.

Strings are interpreted in the host operating system character set and may contain C-escape sequences.

DEFW|DW|WORD expression[,...]

Stores a sequence of 16-bit words in low-high byte order (little endian) at the current location.

Expressions may be computed at the link phase, i.e. they may refer to external or address symbols.

DEFDB|DDB expression[,...]

Stores a sequence of 16-bit words in high-low byte order (big endian) at the current location.

Expressions may be computed at the link phase, i.e. they may refer to external or address symbols.

DEFP|DP|PTR expression[,...]

Stores a sequence of 24-bit words in low-high byte order (little endian) at the current location.

Expressions may be computed at the link phase, i.e. they may refer to external or address symbols.

DEFQ|DQ|DWORD expression[,...]

Stores a sequence of 32-bit words in low-high byte order (little endian) at the current location.

Expressions may be computed at the link phase, i.e. they may refer to external or address symbols.

DEFC|DC name = expression, ...

Define a symbol variable that may either be a constant or an expression.

Expressions may be computed at the link phase, i.e. they may refer to external or address symbols.

DEFGROUP { name[=expression], ... }

Define a set of symbols like the C enum statement. The symbol values start at zero and are incremented for each consecutive symbol, or a new value can be defined with the optional constant expression, e.g.

  DEFGROUP  
  {  
     sym_null  
     sym_ten = 10, sym_eleven, sym_twelve  
  }

DEFINE name,...

Defines a set of symbols as logically true (1).

DEFS size[, fill_byte]

Allocate a storage area of the given size with the given fill_byte, where size and fill_byte are constant expressions.

If the fill_byte is not supplied, it defaults to zero or to the value supplied in the command line -fVALUE option.

DEFS|DS size, "string"

Create a fixed-length string, filling the remaining space, if any, with the filler byte (default zero or the value of the -fVALUE option), e.g.

  DEFS 10, "hello" ; => "hello", 0,0,0,0,0

DEFVARS origin { [name] size_id count, ... }

Define a set of symbols like the C struct statement.

origin is a constant expression that defines the base address of the structure elements. If origin is -1, then the structure elements follow the values of the previous DEFVARS statement that had an origin different from zero. The origin=0 structures are not continued with -1.

name is the symbol that is defined with the structure offset, i.e. origin for the first symbol, and incremented by the size of each element for the subsequent elements.

size_id is one of the following identifiers:

size_id	size
DS.B	8-bits
DS.W	16-bits
DS.P	24-bits
DS.Q	32-bits

count is the number of size_id elements stored at the location.

Example:

  DEFVARS $4000 
  {
    v1    DS.B 1          ; v1 = $4000
    v2    DS.B 3          ; v2 = $4001
    v3    DS.W 1          ; v3 = $4004
          DS.W 1          ; reserve one word
  }
  DEFVARS 0               ; stand-alone struct
  {
    prev  DS.W 1          ; prev = 0
    next  DS.W 1          ; next = 2
    data  DS.w 1          ; data = 4
  }
  DEFVARS -1              ; continue $4000 struct
  {
    v4    DS.Q 1          ; v4 = $4008
  }