mirror of https://github.com/safiire/n65.git
88 lines
2.3 KiB
Ruby
88 lines
2.3 KiB
Ruby
# frozen_string_literal: true
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require_relative '../instruction_base'
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require_relative '../regexes'
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module N65
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# This directive to include bytes
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class Bytes < InstructionBase
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class InvalidByteValue < StandardError; end
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# Try to parse an incbin directive
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def self.parse(line)
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match_data = line.match(/^\.bytes\s+(.+)$/)
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return nil if match_data.nil?
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bytes_array = match_data[1].split(',').map do |byte_string|
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# Does byte_string represent a numeric literal, or is it a symbol?
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# In numeric captures $2 is always binary, $1 is always hex
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case byte_string.strip
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when Regexp.new("^#{Regexes::Num8}$")
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$2.nil? ? $1.to_i(16) : $2.to_i(2)
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when Regexp.new("^#{Regexes::Num16}$")
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value = $2.nil? ? $1.to_i(16) : $2.to_i(2)
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# Break value up into two bytes
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high = (0xff00 & value) >> 8
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low = (0x00ff & value)
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[low, high]
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when Regexp.new("^#{Regexes::Sym}$")
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$1
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else
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raise(InvalidByteValue, byte_string)
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end
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end.flatten
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Bytes.new(bytes_array)
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end
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# Initialize with a byte array
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def initialize(bytes_array)
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@bytes_array = bytes_array
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end
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# Execute on the assembler
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def exec(assembler)
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promise = assembler.with_saved_state do |saved_assembler|
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@bytes_array.map! do |byte|
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case byte
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when Integer
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byte
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when String
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saved_assembler.symbol_table.resolve_symbol(byte)
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else
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raise(InvalidByteValue, byte)
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end
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end
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saved_assembler.write_memory(@bytes_array)
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end
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begin
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promise.call
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rescue SymbolTable::UndefinedSymbol
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# Write the bytes but assume a zero page address for all symbols
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# And just write 0xDE for a placeholder
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placeholder_bytes = @bytes_array.map do |byte|
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case bytes
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when Integer
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byte
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when String
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0xDE
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else
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raise(InvalidByteValue, byte)
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end
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end
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assembler.write_memory(placeholder_bytes)
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promise
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end
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end
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# Display, I don't want to write all these out
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def to_s
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".bytes (#{@bytes_array.length})"
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end
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end
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end
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