class Z80::Program::Register

Z80 registers are populated as singleton methods. You must not create instances of this class directly.

Available registers for use within your programs:

a, b, c, d, e, h, l, ixh, ixl, iyh, iyl, af, bc, de, hl, ix, iy, sp, i, r

There are also special registers internally used by the compiler which indicate indirect memory access:

bc_, de_, hl_, iy_, ix_, sp_ # do not use them in your programs

Instead for addressing values with registers in memory use one-element array wrapped around a 16bit register:

[bc], [de], [hl], [iy - 2], [ix + 1], [sp]

Sometimes it's desired to use arguments in macros as 8bit registers and a pair of them as 16bit register. It's possible thanks to Register#split and Register#| methods:

macro :foo do |_, rh, rl, tt|
  th, tl = tt.split
           ld  rh|rl, tl
           inc rh|rl
           ld  rh|rl, th
end

foo h, l, bc

Attributes

index[RW]

name[R]

prefix[R]

to_s[R]

to_str[R]

Public Class Methods

[](index) click to toggle source

# File lib/z80/registers.rb, line 43
def [](index)
        @@registers[index]
end

names() click to toggle source

# File lib/z80/registers.rb, line 46
def names
        @@names8 + @@namesi8 + @@names_index8 + @@names_bcdep8 + @@names16 + @@names_index16 + @@names_other
end

new(name, opc) click to toggle source

# File lib/z80/registers.rb, line 51
def initialize(name, opc)
        @name = name
        @index = 0
        @opc = opc & 0xff
        @bit8 = name.size != 2 && opc & 7 == opc
        @prefix = name.index(?x) ? "\xDD" : name.index(?y) ? "\xFD" : nil
end

Public Instance Methods

+(other) click to toggle source

This method makes possible to write indexed expressions with ix/iy registers. Example:

ld a, [ix + 7]

# File lib/z80/registers.rb, line 126
def +(other)
        self[other, :+]
end

-(other) click to toggle source

This method makes possible to write indexed expressions with ix/iy registers. Example:

ld a, [ix - 7]

# File lib/z80/registers.rb, line 132
def -(other)
        self[other, :-]
end

[](index = 0, sgn = :+) click to toggle source

Method used internally by mnemonics to make pointer of a label or register. Example:

ld  b, [ix + 2]
ld  [hl], b

# File lib/z80/registers.rb, line 99
def [](index = 0, sgn = :+)
        raise Syntax, "sgn must be :+ or :- only" unless sgn == :+ or sgn == :-
        if name.size == 2 or pointer?
                if index != 0 and name[0] != ?i
                        raise Syntax, "Only ix and iy registers may be pointers with an index."
                elsif !index.respond_to?(:to_alloc)
                        sindex = sgn == :+ ? index.to_i : -index.to_i
                        raise Syntax, "Pointer index out of range." unless (-128..127).include?(sindex)
                end
                raise Syntax, "Register #{name} can not be a pointer." unless r = @@regindex[name + '_'] or (pointer? and r = self)
                r = r.dup
                if r.index == 0
                        r.index = sgn == :- ? -index : index
                elsif index.respond_to?(:to_alloc) and !r.index.respond_to?(:to_alloc)
                        r.index = index.send(sgn, r.index)
                elsif index != 0
                        r.index = r.index.send(sgn, index)
                end
                r
        else
                raise Syntax, "Only 16-bits registers may be pointers."
        end
end

bit8?() click to toggle source

# File lib/z80/registers.rb, line 145
def bit8?; @bit8; end

match16?(other) click to toggle source

Checks if self can adjoin with other: self|other

# File lib/z80/registers.rb, line 66
def match16?(other)
        other.is_a?(Register) and %w[bc de hl ixhixl iyhiyl].include?(name + other.name)
end

one_of?(ary) click to toggle source

# File lib/z80/registers.rb, line 146
def one_of?(ary); ary.include?(name); end

pointer?() click to toggle source

# File lib/z80/registers.rb, line 61
def pointer?
        name[-1] == '_'
end

size() click to toggle source

# File lib/z80/registers.rb, line 58
def size
        name.size
end

split() click to toggle source

Disjoins one of 16 bit registers: bc de hl ix or iy to array of 8bit registers: [hi, lo].

Useful when defining macros that may use registers passed by parameters.

# File lib/z80/registers.rb, line 73
def split
        case name
        when 'bc', 'de', 'hl'
                [@@regindex[name[0]], @@regindex[name[1]]]
        when 'ix', 'iy'
                [@@regindex[name + 'h'], @@regindex[name + 'l']]
        else
                raise Syntax, "Only paired registers: bc, de, hl, ix, iy can be disjoined."
        end
end

to_debug() click to toggle source

# File lib/z80/registers.rb, line 135
def to_debug
        if pointer?
                "(#{name[0,2]}" + if prefix
                        '%.1s%02xH'
                end.to_s + ')'
        else
                name
        end
end

to_i() click to toggle source

# File lib/z80/registers.rb, line 144
def to_i; @opc; end

|(other) click to toggle source

Adjoins two 8 bit registers to form one 16 bit register.

Useful when defining macros that may use registers passed by parameters.

# File lib/z80/registers.rb, line 87
def |(other)
        if match16? other
                @@regindex[name + other.name] || @@regindex[name[0,2]]
        else
                raise Syntax, "Only paired registers: bc, de, hl, ix, iy can be adjoined."
        end
end