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n65/utils/opcode_table_to_yaml.rb

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2015-02-18 03:05:37 +00:00
#!/usr/bin/env ruby
###############################################################################
## http://www.6502.org/tutorials/6502opcodes.html
## This web page has information about each and every 6502 instruction
## Specifically:
##
## - Description of what each of the instructions do
## - Which modes are supported by which instructions, immediate, zero page
## zero page x, and y, absolute, indirect, relative etc.
## - The hex codes each instruction assembles to, in each mode.
## - The lengths in bytes of each instruction, by mode
## - The possibly variable number of cycles each instruction takes.
##
## There are 56 of them, and in my programmer laziness I just wrote this
## script to parse the page into the data structure that you see in
## opcodes.yaml. This really helped in creating the assembler, and
## it had basically everything I needed to know, and sped up writing
## this by huge factor. So, yay to this page, and this script!
require 'yaml'
## Instruction name, and output structure to fill in.
name = :adc
output = {name => {}}
## Copy paste the tables from that website into this heredoc:
text =<<-TEXT
Immediate ADC #$44 $69 2 2
Zero Page ADC $44 $65 2 3
Zero Page,X ADC $44,X $75 2 4
Absolute ADC $4400 $6D 3 4
Absolute,X ADC $4400,X $7D 3 4+
Absolute,Y ADC $4400,Y $79 3 4+
Indirect,X ADC ($44,X) $61 2 6
Indirect,Y ADC ($44),Y $71 2 5+
TEXT
## And now iterate over each line to extract the info
lines = text.split(/\n/)
lines.each do |line|
## Grab out the values we care about
parts = line.split
cycles, len, hex = parts[-1], parts[-2], parts[-3]
hex = "0x%X" % hex.gsub('$', '').to_i(16)
match_data = cycles.match(/([0-9]+)(\+?)/)
cycles = match_data[1]
boundary = match_data[2]
hash = {:hex => hex, :len => len, :cycles => cycles, :boundry_add => boundary != ""}
## And now decide which mode the line belongs to, collecting each listed mode
hash = case line
when /^Accumulator/
{:accumulator => hash}
when /^Immediate/
{:immediate => hash}
when /^Zero Page,X/
{:zero_page_x => hash}
when /^Zero Page,Y/
{:zero_page_y => hash}
when /^Zero Page/
{:zero_page => hash}
when /^Absolute,X/
{:absolute_x => hash}
when /^Absolute,Y/
{:absolute_y => hash}
when /^Absolute/
{:absolute => hash}
when /^Indirect,X/
{:indirect_x => hash}
when /^Indirect,Y/
{:indirect_y => hash}
when /^Indirect/
{:indirect => hash}
when /^Implied/
{:implied => hash}
else
{}
end
output[name].merge!(hash)
end
## Now output some yaml, and I only had to do this about 45 times
## instead of laboriously and mistak-pronely doing it by hand.
puts YAML.dump(output).gsub("'", '')
## See opcodes.yaml