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Linted instruction.rb a bit

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Saf 2020-08-30 12:35:07 -07:00
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lib/n65/instruction.rb
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@ -1,153 +1,150 @@
# frozen_string_literal: true
require_relative 'opcodes' require_relative 'opcodes'
require_relative 'regexes' require_relative 'regexes'
module N65 module N65
# Represents a single 6502 Instruction
####
## Represents a single 6502 Instruction
class Instruction class Instruction
attr_reader :op, :arg, :mode, :hex, :description, :length, :cycles, :boundry_add, :flags, :address attr_reader :op, :arg, :mode, :hex, :description, :length, :cycles, :boundry_add, :flags, :address
## Custom Exceptions # Custom Exceptions
class InvalidInstruction < StandardError; end class InvalidInstruction < StandardError; end
class UnresolvedSymbols < StandardError; end class UnresolvedSymbols < StandardError; end
class InvalidAddressingMode < StandardError; end class InvalidAddressingMode < StandardError; end
class AddressOutOfRange < StandardError; end class AddressOutOfRange < StandardError; end
class ArgumentTooLarge < StandardError; end class ArgumentTooLarge < StandardError; end
## Include Regexes # Include Regexes
include Regexes include Regexes
AddressingModes = { ADDRESSING_MODES = {
:relative => { relative: {
:example => 'B** my_label', example: 'B** my_label',
:display => '%s $%.4X', display: '%s $%.4X',
:regex => /$^/i, # Will never match this one regex: /$^/i,
:regex_label => /^#{Branches}\s+#{Sym}$/ regex_label: /^#{Branches}\s+#{Sym}$/
}, },
:immediate => { immediate: {
:example => 'AAA #$FF', example: 'AAA #$FF',
:display => '%s #$%.2X', display: '%s #$%.2X',
:regex => /^#{Mnemonic}\s+#{Immediate}$/, regex: /^#{Mnemonic}\s+#{Immediate}$/,
:regex_label => /^#{Mnemonic}\s+#(<|>)#{Sym}$/ regex_label: /^#{Mnemonic}\s+#(<|>)#{Sym}$/
}, },
:implied => { implied: {
:example => 'AAA', example: 'AAA',
:display => '%s', display: '%s',
:regex => /^#{Mnemonic}$/ regex: /^#{Mnemonic}$/
}, },
:zero_page => { zero_page: {
:example => 'AAA $FF', example: 'AAA $FF',
:display => '%s $%.2X', display: '%s $%.2X',
:regex => /^#{Mnemonic}\s+#{Num8}$/, regex: /^#{Mnemonic}\s+#{Num8}$/,
:regex_label => /^#{Mnemonic}\s+#{Sym}\s+zp$/ regex_label: /^#{Mnemonic}\s+#{Sym}\s+zp$/
}, },
:zero_page_x => { zero_page_x: {
:example => 'AAA $FF, X', example: 'AAA $FF, X',
:display => '%s $%.2X, X', display: '%s $%.2X, X',
:regex => /^#{Mnemonic}\s+#{Num8}\s?,\s?#{XReg}$/, regex: /^#{Mnemonic}\s+#{Num8}\s?,\s?#{XReg}$/,
:regex_label => /^#{Mnemonic}\s+#{Sym}\s?,\s?#{XReg}\s+zp$/ regex_label: /^#{Mnemonic}\s+#{Sym}\s?,\s?#{XReg}\s+zp$/
}, },
:zero_page_y => { zero_page_y: {
:example => 'AAA $FF, Y', example: 'AAA $FF, Y',
:display => '%s $%.2X, Y', display: '%s $%.2X, Y',
:regex => /^#{Mnemonic}\s+#{Num8}\s?,\s?#{YReg}$/, regex: /^#{Mnemonic}\s+#{Num8}\s?,\s?#{YReg}$/,
:regex_label => /^#{Mnemonic}\s+#{Sym}\s?,\s?#{YReg}\s+zp$/ regex_label: /^#{Mnemonic}\s+#{Sym}\s?,\s?#{YReg}\s+zp$/
}, },
:absolute => { absolute: {
:example => 'AAA $FFFF', example: 'AAA $FFFF',
:display => '%s $%.4X', display: '%s $%.4X',
:regex => /^#{Mnemonic}\s+#{Num16}$/, regex: /^#{Mnemonic}\s+#{Num16}$/,
:regex_label => /^#{Mnemonic}\s+#{Sym}$/ regex_label: /^#{Mnemonic}\s+#{Sym}$/
}, },
:absolute_x => { absolute_x: {
:example => 'AAA $FFFF, X', example: 'AAA $FFFF, X',
:display => '%s $%.4X, X', display: '%s $%.4X, X',
:regex => /^#{Mnemonic}\s+#{Num16}\s?,\s?#{XReg}$/, regex: /^#{Mnemonic}\s+#{Num16}\s?,\s?#{XReg}$/,
:regex_label => /^#{Mnemonic}\s+#{Sym}\s?,\s?#{XReg}$/ regex_label: /^#{Mnemonic}\s+#{Sym}\s?,\s?#{XReg}$/
}, },
:absolute_y => { absolute_y: {
:example => 'AAA $FFFF, Y', example: 'AAA $FFFF, Y',
:display => '%s $%.4X, Y', display: '%s $%.4X, Y',
:regex => /^#{Mnemonic}\s+#{Num16}\s?,\s?#{YReg}$/, regex: /^#{Mnemonic}\s+#{Num16}\s?,\s?#{YReg}$/,
:regex_label => /^#{Mnemonic}\s+#{Sym}\s?,\s?#{YReg}$/ regex_label: /^#{Mnemonic}\s+#{Sym}\s?,\s?#{YReg}$/
}, },
:indirect => { indirect: {
:example => 'AAA ($FFFF)', example: 'AAA ($FFFF)',
:display => '%s ($%.4X)', display: '%s ($%.4X)',
:regex => /^#{Mnemonic}\s+\(#{Num16}\)$/, regex: /^#{Mnemonic}\s+\(#{Num16}\)$/,
:regex_label => /^#{Mnemonic}\s+\(#{Sym}\)$/ regex_label: /^#{Mnemonic}\s+\(#{Sym}\)$/
}, },
:indirect_x => { indirect_x: {
:example => 'AAA ($FF, X)', example: 'AAA ($FF, X)',
:display => '%s ($%.2X, X)', display: '%s ($%.2X, X)',
:regex => /^#{Mnemonic}\s+\(#{Num8}\s?,\s?#{XReg}\)$/, regex: /^#{Mnemonic}\s+\(#{Num8}\s?,\s?#{XReg}\)$/,
:regex_label => /^#{Mnemonic}\s+\(#{Sym}\s?,\s?#{XReg}\)$/ regex_label: /^#{Mnemonic}\s+\(#{Sym}\s?,\s?#{XReg}\)$/
}, },
:indirect_y => { indirect_y: {
:example => 'AAA ($FF), Y)', example: 'AAA ($FF), Y)',
:display => '%s ($%.2X), Y', display: '%s ($%.2X), Y',
:regex => /^#{Mnemonic}\s+\(#{Num8}\)\s?,\s?#{YReg}$/, regex: /^#{Mnemonic}\s+\(#{Num8}\)\s?,\s?#{YReg}$/,
:regex_label => /^#{Mnemonic}\s+\(#{Sym}\)\s?,\s?#{YReg}$/ regex_label: /^#{Mnemonic}\s+\(#{Sym}\)\s?,\s?#{YReg}$/
}
} }
}.freeze
#### # Parse one line of assembly, returns nil if the line
## Parse one line of assembly, returns nil if the line # is ultimately empty of asm instructions
## is ultimately empty of asm instructions # Raises SyntaxError if the line is malformed in some way
## Raises SyntaxError if the line is malformed in some way
def self.parse(line) def self.parse(line)
# Try to parse this line in each addressing mode
## Try to parse this line in each addressing mode ADDRESSING_MODES.each do |mode, parse_info|
AddressingModes.each do |mode, parse_info| # We have regexes that match each addressing mode
## We have regexes that match each addressing mode
match_data = parse_info[:regex].match(line) match_data = parse_info[:regex].match(line)
unless match_data.nil? unless match_data.nil?
## We must have a straight instruction without symbols, construct # We must have a straight instruction without symbols, construct
## an Instruction from the match_data, and return it # an Instruction from the match_data, and return it
_, op, arg_hex, arg_bin = match_data.to_a _, op, arg_hex, arg_bin = match_data.to_a
## Until I think of something better, it seems that the union regex # Until I think of something better, it seems that the union regex
## puts a hexidecimal argument in one capture, and a binary in the next # puts a hexidecimal argument in one capture, and a binary in the next
## This is annoying, but still not as annoying as using Treetop to parse # This is annoying, but still not as annoying as using Treetop to parse
if arg_hex != nil if !arg_hex.nil?
return Instruction.new(op, arg_hex.to_i(16), mode) return Instruction.new(op, arg_hex.to_i(16), mode)
elsif arg_bin != nil elsif !arg_bin.nil?
return Instruction.new(op, arg_bin.to_i(2), mode) return Instruction.new(op, arg_bin.to_i(2), mode)
else else
return Instruction.new(op, nil, mode) return Instruction.new(op, nil, mode)
end end
else else
## Can this addressing mode even use labels? # Can this addressing mode even use labels?
unless parse_info[:regex_label].nil? unless parse_info[:regex_label].nil?
## See if it does in fact have a symbolic argument # See if it does in fact have a symbolic argument
match_data = parse_info[:regex_label].match(line) match_data = parse_info[:regex_label].match(line)
unless match_data.nil? unless match_data.nil?
## We have found an assembly instruction containing a symbolic # We have found an assembly instruction containing a symbolic
## argument. We can resolve this symbol later by looking at the # argument. We can resolve this symbol later by looking at the
## symbol table in the #exec method # symbol table in the #exec method
match_array = match_data.to_a match_array = match_data.to_a
## If we have a 4 element array, this means we matched something # If we have a 4 element array, this means we matched something
## like LDA #<label, which is a legal immediate one byte value # like LDA #<label, which is a legal immediate one byte value
## by taking the msb. We need to make that distinction in the # by taking the msb. We need to make that distinction in the
## Instruction, by passing an extra argument # Instruction, by passing an extra argument
if match_array.size == 4 if match_array.size == 4
_, op, byte_selector, arg = match_array _, op, byte_selector, arg = match_array
return Instruction.new(op, arg, mode, byte_selector.to_sym) return Instruction.new(op, arg, mode, byte_selector.to_sym)
@ -160,60 +157,49 @@ module N65
end end
end end
## We just don't recognize this line of asm, it must be a Syntax Error # We just don't recognize this line of asm, it must be a Syntax Error
fail(SyntaxError, line) raise(SyntaxError, line)
end end
# Create an instruction. Having the instruction op a downcased symbol is nice
#### # because that can later be used to index into our opcodes hash in OpCodes
## Create an instruction. Having the instruction op a downcased symbol is nice # OpCodes contains the definitions of each OpCode
## because that can later be used to index into our opcodes hash in OpCodes
## OpCodes contains the definitions of each OpCode
def initialize(op, arg, mode, byte_selector = nil) def initialize(op, arg, mode, byte_selector = nil)
@byte_selector = byte_selector.nil? ? nil : byte_selector.to_sym @byte_selector = byte_selector.nil? ? nil : byte_selector.to_sym
fail(InvalidInstruction, "Bad Byte selector: #{byte_selector}") unless [:>, :<, nil].include?(@byte_selector) raise(InvalidInstruction, "Bad Byte selector: #{byte_selector}") unless [:>, :<, nil].include?(@byte_selector)
## Lookup the definition of this opcode, otherwise it is an invalid instruction ## Lookup the definition of this opcode, otherwise it is an invalid instruction
@op = op.downcase.to_sym @op = op.downcase.to_sym
definition = OpCodes[@op] definition = OpCodes[@op]
fail(InvalidInstruction, op) if definition.nil? raise(InvalidInstruction, op) if definition.nil?
@arg = arg @arg = arg
## Be sure the mode is an actually supported mode. # Be sure the mode is an actually supported mode.
@mode = mode.to_sym @mode = mode.to_sym
fail(InvalidAddressingMode, mode) unless AddressingModes.has_key?(@mode) raise(InvalidAddressingMode, mode) unless ADDRESSING_MODES.key?(@mode)
raise(InvalidInstruction, "#{op} cannot be used in #{mode} mode") if definition[@mode].nil?
if definition[@mode].nil?
fail(InvalidInstruction, "#{op} cannot be used in #{mode} mode")
end
@description, @flags = definition.values_at(:description, :flags) @description, @flags = definition.values_at(:description, :flags)
@hex, @length, @cycles, @boundry_add = definition[@mode].values_at(:hex, :len, :cycles, :boundry_add) @hex, @length, @cycles, @boundry_add = definition[@mode].values_at(:hex, :len, :cycles, :boundry_add)
end end
# Is this instruction a zero page instruction?
####
## Is this instruction a zero page instruction?
def zero_page_instruction? def zero_page_instruction?
[:zero_page, :zero_page_x, :zero_page_y].include?(@mode) %i[zero_page zero_page_x zero_page_y].include?(@mode)
end end
# Execute writes the emitted bytes to virtual memory, and updates PC
#### # If there is a symbolic argument, we can try to resolve it now, or
## Execute writes the emitted bytes to virtual memory, and updates PC # promise to resolve it later.
## If there is a symbolic argument, we can try to resolve it now, or
## promise to resolve it later.
def exec(assembler) def exec(assembler)
promise = assembler.with_saved_state do |saved_assembler| promise = assembler.with_saved_state do |saved_assembler|
@arg = saved_assembler.symbol_table.resolve_symbol(@arg) @arg = saved_assembler.symbol_table.resolve_symbol(@arg)
## If the instruction uses a byte selector, we need to apply that. # If the instruction uses a byte selector, we need to apply that.
@arg = apply_byte_selector(@byte_selector, @arg) @arg = apply_byte_selector(@byte_selector, @arg)
## If the instruction is relative we need to work out how far away it is # If the instruction is relative we need to work out how far away it is
@arg = @arg - saved_assembler.program_counter - 2 if @mode == :relative @arg = @arg - saved_assembler.program_counter - 2 if @mode == :relative
saved_assembler.write_memory(emit_bytes) saved_assembler.write_memory(emit_bytes)
@ -224,23 +210,22 @@ module N65
assembler.write_memory(emit_bytes) assembler.write_memory(emit_bytes)
when String when String
begin begin
## This works correctly now :) # This works correctly now :)
promise.call promise.call
rescue SymbolTable::UndefinedSymbol rescue SymbolTable::UndefinedSymbol
placeholder = [@hex, 0xDE, 0xAD][0...@length] placeholder = [@hex, 0xDE, 0xAD][0...@length]
## I still have to write a placeholder instruction of the right # I still have to write a placeholder instruction of the right
## length. The promise will come back and resolve the address. # length. The promise will come back and resolve the address.
assembler.write_memory(placeholder) assembler.write_memory(placeholder)
return promise promise
end end
end end
end end
# Apply a byte selector to an argument
####
## Apply a byte selector to an argument
def apply_byte_selector(byte_selector, value) def apply_byte_selector(byte_selector, value)
return value if byte_selector.nil? return value if byte_selector.nil?
case byte_selector case byte_selector
when :> when :>
high_byte(value) high_byte(value)
@ -249,47 +234,39 @@ module N65
end end
end end
# Emit bytes from asm structure
####
## Emit bytes from asm structure
def emit_bytes def emit_bytes
case @length case @length
when 1 when 1
[@hex] [@hex]
when 2 when 2
if zero_page_instruction? && @arg < 0 || @arg > 0xff if zero_page_instruction? && @arg.netagive? || @arg > 0xff
fail(ArgumentTooLarge, "For #{@op} in #{@mode} mode, only 8-bit values are allowed") raise(ArgumentTooLarge, "For #{@op} in #{@mode} mode, only 8-bit values are allowed")
end end
[@hex, @arg] [@hex, @arg]
when 3 when 3
[@hex] + break_16(@arg) [@hex] + break_16(@arg)
else else
fail("Can't handle instructions > 3 bytes") raise("Can't handle instructions > 3 bytes")
end end
end end
private private
####
## Break an integer into two 8-bit parts # Break an integer into two 8-bit parts
def break_16(integer) def break_16(integer)
[integer & 0x00FF, (integer & 0xFF00) >> 8] [integer & 0x00FF, (integer & 0xFF00) >> 8]
end end
# Take the high byte of a 16-bit integer
####
## Take the high byte of a 16-bit integer
def high_byte(word) def high_byte(word)
(word & 0xFF00) >> 8 (word & 0xFF00) >> 8
end end
# Take the low byte of a 16-bit integer
####
## Take the low byte of a 16-bit integer
def low_byte(word) def low_byte(word)
word & 0xFF word & 0xFF
end end
end end
end end