NAME

CPU::Z80::Assembler::Parser - Instruction parser for the Z80 assembler

SYNOPSIS

    use CPU::Z80::Assembler::Parser;
    use HOP::Stream 'drop';

    my $stream = z80parser($z80lexer);
    my $value = eval_expr($expr, $address, \%symbol_table)

DESCRIPTION

This module transforms the sequence of tokens retrieved from CPU::Z80::Assembler::Lexer into a sequence of decoded assembly instructions.

EXPORTS

By default the 'z80parser' and 'eval_expr' subroutines are exported. To disable that, do:

    use CPU::Z80::Assembler::Parser ();

FUNCTIONS

z80parser

This takes as parameter a HOP::Stream as returned by z80lexer, and returns a HOP::Stream with the tokes described below.

eval_expr

This takes as parameter an expression as a HOP::Stream of tokens, the current address of the expression (to evaluate the '$' expression) and a reference to a hash with all defined symbols. Each symbol may be either a scalar value, or an expression. The eval_expr function evaluates recursively all the sub-expressions and returns the value. It dies if any used label is not defined, or if there is a circular reference.

TOKENS

The following tokens are returned by the stream:

    ["LINE", $line_text, $line_nr, $file]

Indicates that the next tokens belong to the given file, and line number, and contains the whole line text. This token is usefull to remember the current location in the source file, to show in listings or error messages.

    ["org", address]

Translation of an ORG instruction with the address argument.

    ["LABEL", name]

Defines the label with the given name at the current location.

    ["LABEL", name, expr]

Defines the label with the given name as the result of evaluating the given expression. The expression is only evaluated on pass 2, after all labels are defined. An expression is a HOP::Stream containing all the tokens of the expression.

    ["OPCODE", byte, [type, expr] ]

Defines an assembled opcode with the list of bytes to load to the object code.

The bytes that need to be computed as the result of an expression evaluation are returned as a pair [type, expression], where type is:

"sb"

for signed byte;

"ub"

for unsigned byte;

"w"

for word. When a "w" expression is used, the "OPCODE" token includes an empty array ref, so that the size of the instruction matches the size of the token array minus 1.

An expression is a HOP::Stream containing all the tokens of the expression.

BUGS and FEEDBACK

See CPU::Z80::Assembler.

SEE ALSO

HOP::Stream CPU::Z80::Assembler CPU::Z80::Assembler::Lexer

AUTHORS, COPYRIGHT and LICENCE

See CPU::Z80::Assembler.