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# File 'lib/micro_cisc/compile/instruction.rb', line 149
def parse(operation)
@operation = operation
components = @components[1..-1]
args = []
@immediates = []
@uses_mem_arg = false
@source_is_mem = false
@dest_is_mem = false
while components.size > 0
to_parse = components.shift
if(to_parse.start_with?('$') || to_parse.start_with?('&'))
raise ArgumentError, "Missing ref #{to_parse}" unless @statement.get_var(to_parse)
to_parse = @statement.get_var(to_parse)
components = to_parse.split(/\s/) + components
to_parse = components.shift
end
parsed = parse_component(to_parse)
if ['val', 'reg', 'mem'].include?(parsed.last)
@uses_mem_arg = true if parsed.last == 'mem'
@source_is_mem = true if args.empty? && parsed.last == 'mem'
@dest_is_mem = true if !args.empty? && parsed.last == 'mem'
args << parsed
@immediates << 0
elsif parsed.last == 'op'
@alu_code = validate_alu(parsed, @alu_code)
elsif parsed.last == 'push'
@inc = validate_boolean(parsed, @sign)
elsif parsed.last == 'pop'
@inc = validate_boolean(parsed, @sign)
elsif parsed.last == 'eff'
@eff = validate_effect(parsed, @eff)
elsif (parsed.last == 'disp' || parsed.last == 'imm')
if args.empty?
args << [4, 'val']
@immediates << 0
end
imm =
if parsed.first.is_a?(Numeric)
parsed.first
else
if parsed.first == 'break'
[@label_generator.end_label, parsed.last]
elsif parsed.first == 'loop'
[@label_generator.start_label, parsed.last]
else
parsed
end
end
@immediates[args.size - 1] = imm
else
raise ArgumentError, "Invalid argument for #{@operation}: #{to_parse}"
end
end
if args.size != 2
raise ArgumentError, "Missing source and/or destination arguments"
end
@eff ||= 3
if @inc && !@uses_mem_arg
raise ArgumentError, "Memory argument required to use push and pop"
end
if @operation == 'alu' && !@alu_code
raise ArgumentError, "Compute instruction must have ALU op code"
end
@inc ||= 0
@bit_width = 7
@bit_width -= 4 if @operation == 'alu'
@bit_width -= 1 if @uses_mem_arg
@immediates.each_with_index do |imm, index|
if imm.is_a?(Numeric)
validate_immediate(imm, index)
end
end
if @immediates.last != 0 && @operation == 'alu'
raise ArgumentError, "Destination immediate is not allowed for compute instructions"
elsif @immediates.last != 0 && (!@source_is_mem || !@dest_is_mem)
raise ArgumentError, "Destination immediate is only allowed when both arguments are mem args"
end
@src, @dest, @dir = validate_args(args.first, args.last)
nil
end
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