#!/usr/bin/env python3
#
# This script reads the original Z80 PLA table and processes it to get the list of PLA
# entries in the form suitable to load into the PLA checker program.
#
# Format of the output PLA table:
# 7 bits of modifiers:
# loc 0 If "1", IX or IY flag is reset |\
# 1 If "1", IX or IY flag is set | Only 1 of these 2 can be set
# 2 If "1", in HALT state
# 3 If "1", ALU operation
# 4 If "1", XX regular instruction |\
# 5 If "1", CB instruction table modifier | Only 1 of these 3 can be set
# 6 If "1", ED instruction table modifier |/
#
# Following 16 bits of opcode test in pairs, from bit7 to bit0
# For each pair, if the left bit is "1", the opcode bit has to be 0
# if the right bit is "1", the opcode bit has to be 1
# otherwise the bit is ignored
#
#-------------------------------------------------------------------------------
# Copyright (C) 2014 Goran Devic
#
# This program is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the Free
# Software Foundation; either version 2 of the License, or (at your option)
# any later version.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
# more details.
#-------------------------------------------------------------------------------
import string
import os
# Input PLA table: a text file representing the original (Z80 reverse-engineered)
# table at http://arcfn.com/files/z80-pla-table.html
inFile = "z80-pla-original.txt"
# Output processed PLA table
outFile = "z80-pla.txt"
table = []
def xtostr ( condition ):
if condition:
return "1"
return "."
# Read the content of the input PLA table and add all valid lines (starting with a number)
with open(inFile, 'r') as fIn:
for line in fIn:
seg = line.split()
if len(seg)>1 and seg[0].isdigit():
table.append(line)
# In the original PLA table, entries are listed in reverse order -
table.reverse()
# Control ID to detect errors
controlID = 0
with open(outFile, 'w') as fOut:
fOut.write("# Automatically generated by process-pla.py\n")
pla = []
for entry in table:
# This is an example of an input PLA entry containing different segments:
# ID ALU XX CB ED 0 /0 1 /1 2 /2 6 /6 7 /7 3 /3 4 /4 5 /5 Instruction Ex Description
# 59 1 1 . . . . . . . . . 1 1 . 1 . . 1 . 1 01110xxx ce ld (hl),r (and hlt)
# 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
seg = entry.split()
if len(seg)>22:
# Sanity check
if controlID!=int(seg[0]):
fOut.write("Unexpected entry " + seg[0])
exit(-1)
controlID = controlID + 1
# Decipher [22] into actual PLA entry lines IXY0, IXY1 and HALT (a, b, c)
entry = ""
entry += xtostr("a" in seg[22])
entry += xtostr("b" in seg[22])
entry += xtostr("c" in seg[22])
# Append the rest of the PLA modifiers: ALU, XX, CB and ED
entry += seg[1] + seg[2] + seg[3] + seg[4] + ' '
# Add the instruction decoder bit7 through bit0 in that order
# 7 /7 6 /6 5 /5 4 /4 3 /3 2 /2 1 /1 0 /0
entry += seg[13]+seg[14] +seg[11]+seg[12] +seg[19]+seg[20] +seg[17]+seg[18] +seg[15]+seg[16] +seg[9]+seg[10] +seg[7]+seg[8] +seg[5]+seg[6]
# Check if the new PLA entry is a duplicate (already stored to PLA)
# Append "D" for duplicate entries so they can be skipped easily
if entry in pla:
fOut.write(entry + "\tD\t")
else:
# Store the new PLA line in the PLA list and write it out
pla.append(entry)
fOut.write(entry + "\t-\t")
# Write the ID number, text decode and description
fOut.write(seg[0] + "\t" + seg[21] + "\t" + ' '.join(seg[23:len(seg)]) + "\n")
# The original PLA table passes individual opcode bits that are needed to decode many
# instructions but it does not contain concrete single-bit entries
# We append those bits to the end of our PLA table
fOut.write("....... ...............1\t-\t99\txxxxxxx1\topcode[0]\n")
fOut.write("....... .............1..\t-\t100\txxxxxx1x\topcode[1]\n")
fOut.write("....... ...........1....\t-\t101\txxxxx1xx\topcode[2]\n")
fOut.write("....... .........1......\t-\t102\txxxx1xxx\topcode[3]\n")
fOut.write("....... .......1........\t-\t103\txxx1xxxx\topcode[4]\n")
fOut.write("....... .....1..........\t-\t104\txx1xxxxx\topcode[5]\n")
