Subversion Repositories a-z80

#!/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")