什麼約6502彙編由大衛比茲利：
#!/usr/bin/env python3
# asm6502.py
"""
A simple but powerful 6502 assembler
Author : David Beazley (http://www.dabeaz.com)
Copyright (C) 2010
Parses assembly language of the following form:
var=value ; Variable assignment
label: OP ADDR ; Labeled opcode and address
OP ADDR ; Opcode and address
Addressing modes are as follows:
#value ; immediate mode (8-bit value)
%value ; zero-page mode
%value,X ; zero-page X indexed
%value,Y ; zero-page Y indexed
value ; absolute
value,X ; absolute Y indexed
value,Y ; absolute Y indexed
[value] ; indirect
[value,X] ; indirect, X indexed
[value,Y] ; indirect, Y indexed
values and labels can be any Python expression, but the final value must
evaluate to an integer value. Use a numeric label to set the memory
location of instructions to follow.
"""
from collections import Callable
import re
# Exception used for errors
class AssemblyError(Exception): pass
# Functions used in the creation of object code (used in the table below)
def VALUE_L(pc, value):
return value & 0xff
def VALUE_H(pc, value):
return (value & 0xff00) >> 8
def RELATIVE_ADDR(pc, value):
offset = value - (pc + 2)
return offset & 0xff
# Table of 6502 opcodes and supported addressing modes
opcodes_6502 = {
'DATA' : {
'immed' : [VALUE_L],
},
'ADC' : {
'immed' : [0x69, VALUE_L],
'zerop' : [0x65, VALUE_L],
'zerop_x' : [0x75, VALUE_L],
'abs' : [0x6D, VALUE_L, VALUE_H],
'abs_x' : [0x7D, VALUE_L, VALUE_H],
'abs_y' : [0x79, VALUE_L, VALUE_H],
'indirect_x' : [0x61, VALUE_L],
'indirect_y' : [0x71, VALUE_L],
},
'AND' : {
'immed' : [0x29, VALUE_L],
'zerop' : [0x25, VALUE_L],
'zerop_x' : [0x35, VALUE_L],
'abs' : [0x2D, VALUE_L, VALUE_H],
'abs_x' : [0x3D, VALUE_L, VALUE_H],
'abs_y' : [0x39, VALUE_L, VALUE_H],
'indirect_x' : [0x21, VALUE_L],
'indirect_y' : [0x31, VALUE_L],
},
'ASL' : {
'accum' : [0x0a],
'zerop' : [0x06, VALUE_L],
'zerop_x' : [0x16, VALUE_L],
'abs' : [0x0e, VALUE_L, VALUE_H],
'abs_x' : [0x1e, VALUE_L, VALUE_H],
},
'BIT' : {
'zerop' : [0x24, VALUE_L],
'abs' : [0x2c, VALUE_L, VALUE_H],
},
'BPL' : {
'immed' : [0x10, VALUE_L],
'abs' : [0x10, RELATIVE_ADDR],
},
'BMI' : {
'immed' : [0x30, VALUE_L],
'abs' : [0x30, RELATIVE_ADDR],
},
'BVC' : {
'immed' : [0x50, VALUE_L],
'abs' : [0x50, RELATIVE_ADDR],
},
'BVS' : {
'immed' : [0x70, VALUE_L],
'abs' : [0x70, RELATIVE_ADDR],
},
'BCC' : {
'immed' : [0x90, VALUE_L],
'abs' : [0x90, RELATIVE_ADDR],
},
'BCS' : {
'immed' : [0xb0, VALUE_L],
'abs' : [0xb0, RELATIVE_ADDR],
},
'BNE' : {
'immed' : [0xd0, VALUE_L],
'abs' : [0xd0, RELATIVE_ADDR],
},
'BEQ' : {
'immed' : [0xf0, VALUE_L],
'abs' : [0xf0, RELATIVE_ADDR],
},
'BRK' : {
'accum' : [0x00],
'immed' : [0x00, VALUE_L],
},
'CMP' : {
'immed' : [0xc9, VALUE_L],
'zerop' : [0xc5, VALUE_L],
'zerop_x' : [0xd5, VALUE_L],
'abs' : [0xcD, VALUE_L, VALUE_H],
'abs_x' : [0xdD, VALUE_L, VALUE_H],
'abs_y' : [0xd9, VALUE_L, VALUE_H],
'indirect_x' : [0xc1, VALUE_L],
'indirect_y' : [0xd1, VALUE_L],
},
'CPX' : {
'immed' : [0xe0, VALUE_L],
'zerop' : [0xe4, VALUE_L],
'abs' : [0xec, VALUE_L, VALUE_H],
},
'CPY' : {
'immed' : [0xc0, VALUE_L],
'zerop' : [0xc4, VALUE_L],
'abs' : [0xcc, VALUE_L, VALUE_H],
},
'DEC' : {
'zerop' : [0xc6, VALUE_L],
'zerop_x' : [0xd6, VALUE_L],
'abs' : [0xce, VALUE_L, VALUE_H],
'abs_x' : [0xde, VALUE_L, VALUE_H],
},
'EOR' : {
'immed' : [0x49, VALUE_L],
'zerop' : [0x45, VALUE_L],
'zerop_x' : [0x55, VALUE_L],
'abs' : [0x4D, VALUE_L, VALUE_H],
'abs_x' : [0x5D, VALUE_L, VALUE_H],
'abs_y' : [0x59, VALUE_L, VALUE_H],
'indirect_x' : [0x41, VALUE_L],
'indirect_y' : [0x51, VALUE_L],
},
'CLC' : {
'accum' : [0x18],
},
'SEC' : {
'accum' : [0x38],
},
'CLI' : {
'accum' : [0x58],
},
'SEI' : {
'accum' : [0x78],
},
'CLV' : {
'accum' : [0xb8],
},
'CLD' : {
'accum' : [0xd8],
},
'SED' : {
'accum' : [0xf8],
},
'INC' : {
'zerop' : [0xe6, VALUE_L],
'zerop_x' : [0xf6, VALUE_L],
'abs' : [0xee, VALUE_L, VALUE_H],
'abs_x' : [0xfe, VALUE_L, VALUE_H],
},
'JMP' : {
'abs' : [0x4c, VALUE_L, VALUE_H],
'indirect' : [0x6c, VALUE_L, VALUE_H]
},
'JSR' : {
'abs' : [0x20, VALUE_L, VALUE_H],
},
'LDA' : {
'immed' : [0xA9, VALUE_L],
'zerop' : [0xA5, VALUE_L],
'zerop_x' : [0xB5, VALUE_L],
'abs' : [0xAD, VALUE_L, VALUE_H],
'abs_x' : [0xBD, VALUE_L, VALUE_H],
'abs_y' : [0xB9, VALUE_L, VALUE_H],
'indirect_x' : [0xA1, VALUE_L],
'indirect_y' : [0xB1, VALUE_L],
},
'LDX' : {
'immed' : [0xa2, VALUE_L],
'zerop' : [0xa6, VALUE_L],
'zerop_y' : [0xb6, VALUE_L],
'abs' : [0xae, VALUE_L, VALUE_H],
'abs_y' : [0xbe, VALUE_L, VALUE_H],
},
'LDY' : {
'immed' : [0xa0, VALUE_L],
'zerop' : [0xa4, VALUE_L],
'zerop_x' : [0xb4, VALUE_L],
'abs' : [0xac, VALUE_L, VALUE_H],
'abs_x' : [0xbc, VALUE_L, VALUE_H],
},
'LSR' : {
'accum' : [0x4a],
'zerop' : [0x46, VALUE_L],
'zerop_x' : [0x56, VALUE_L],
'abs' : [0x4e, VALUE_L, VALUE_H],
'abs_x' : [0x5e, VALUE_L, VALUE_H],
},
'NOP' : {
'accum' : [0xea],
},
'ORA' : {
'immed' : [0x09, VALUE_L],
'zerop' : [0x05, VALUE_L],
'zerop_x' : [0x15, VALUE_L],
'abs' : [0x0D, VALUE_L, VALUE_H],
'abs_x' : [0x1D, VALUE_L, VALUE_H],
'abs_y' : [0x19, VALUE_L, VALUE_H],
'indirect_x' : [0x01, VALUE_L],
'indirect_y' : [0x11, VALUE_L],
},
'TAX' : {
'accum' : [0xaa],
},
'TXA' : {
'accum' : [0x8a],
},
'DEX' : {
'accum' : [0xca],
},
'INX' : {
'accum' : [0xe8],
},
'TAY' : {
'accum' : [0xa8],
},
'TYA' : {
'accum' : [0x98],
},
'DEY' : {
'accum' : [0x88],
},
'INY' : {
'accum' : [0xc8],
},
'ROL' : {
'accum' : [0x2a],
'zerop' : [0x26, VALUE_L],
'zerop_x' : [0x36, VALUE_L],
'abs' : [0x2e, VALUE_L, VALUE_H],
'abs_x' : [0x3e, VALUE_L, VALUE_H],
},
'ROR' : {
'accum' : [0x6a],
'zerop' : [0x66, VALUE_L],
'zerop_x' : [0x76, VALUE_L],
'abs' : [0x6e, VALUE_L, VALUE_H],
'abs_x' : [0x7e, VALUE_L, VALUE_H],
},
'RTI' : {
'accum' : [0x40],
},
'RTS' : {
'accum' : [0x60],
},
'SBC' : {
'immed' : [0xe9, VALUE_L],
'zerop' : [0xe5, VALUE_L],
'zerop_x' : [0xf5, VALUE_L],
'abs' : [0xeD, VALUE_L, VALUE_H],
'abs_x' : [0xfD, VALUE_L, VALUE_H],
'abs_y' : [0xf9, VALUE_L, VALUE_H],
'indirect_x' : [0xe1, VALUE_L],
'indirect_y' : [0xf1, VALUE_L],
},
'STA' : {
'zerop' : [0x85, VALUE_L],
'zerop_x' : [0x95, VALUE_L],
'abs' : [0x8D, VALUE_L, VALUE_H],
'abs_x' : [0x9D, VALUE_L, VALUE_H],
'abs_y' : [0x99, VALUE_L, VALUE_H],
'indirect_x' : [0x81, VALUE_L],
'indirect_y' : [0x91, VALUE_L],
},
'TXS' : {
'accum' : [0x9a],
},
'TSX' : {
'accum' : [0xba],
},
'PHA' : {
'accum' : [0x48],
},
'PLA' : {
'accum' : [0x68],
},
'PHP' : {
'accum' : [0x08],
},
'PLP' : {
'accum' : [0x28],
},
'STX' : {
'zerop' : [0x86, VALUE_L],
'zerop_y' : [0x96, VALUE_L],
'abs' : [0x8e, VALUE_L, VALUE_H],
},
'STY' : {
'zerop' : [0x84, VALUE_L],
'zerop_x' : [0x94, VALUE_L],
'abs' : [0x8c, VALUE_L, VALUE_H],
},
}
# Parse address modes for various 6502 instructions
def parse_address_mode(mode):
# Accumulator or implicit. Example: INC
if not mode or mode == 'A': return ("accum","0")
# Immediate value. Example : LDA #13
if mode.startswith("#"): return ("immed", mode[1:])
# Strip unneeded whitespace if not an immediate value
mode = mode.replace(' ','')
# Zero-page address with indexing. Example : LDA %25, X
if mode.startswith("%"):
if mode.endswith(",X"): return ("zerop_x", mode[1:-2])
elif mode.endswith(",Y"): return ("zerop_y", mode[1:-2])
else: return ("zerop", mode[1:])
# Indirect addressing.Example : LDA [0xFF00, X]
if mode.startswith("["):
if mode.endswith(",X]"): return ("indirect_x", mode[1:-3])
elif mode.endswith(",Y]"): return ("indirect_y",mode[1:-3])
elif mode.endswith("]"): return ("indirect", mode[1:-1])
# Absolute address, with indexing. Example : LDA 0xFF00, X
if mode.endswith(",X"): return ("abs_x",mode[:-2])
elif mode.endswith(",Y"): return ("abs_y",mode[:-2])
else: return ("abs",mode)
# Parse an opcode line into intermediate object code. Returns a tuple
# (value, objcode) where value is a string to be evaluated in the 2nd pass
def parse_opcode(line):
fields = line.split(None,1)
opcode = fields[0]
arg = fields[1] if len(fields) == 2 else ""
mode,value = parse_address_mode(arg)
opcodemodes = opcodes_6502.get(opcode)
if not opcodemodes:
raise AssemblyError("Unknown opcode '%s'" % opcode)
objcode = opcodemodes.get(mode)
if not objcode:
raise AssemblyError("Invalid addressing mode '%s' for opcode %s" % (arg,opcode))
return (value,list(objcode))
# Takes a sequence of lines and strip comments and blanks
def strip_lines(lines):
for line in lines:
comment_index = line.find(";")
if comment_index >= 0:
line = line[:comment_index]
line = line.strip()
yield line
assign_pat = re.compile(r'(\s*)([a-zA-Z_][a-zA-Z0-9_]*)(\s*=)')
# Parse lines into intermediate object code
def parse_lines(lines,symbols):
for lineno,line in enumerate(lines,1):
if assign_pat.match(line):
exec(line,symbols)
else:
label, *colon, statement = line.rpartition(":")
try:
yield lineno, label, parse_opcode(statement) if statement else (None,None)
except AssemblyError as e:
print("{0:4d} : Error : {1}".format(lineno,e))
# Assemble a sequence of lines into binary
def assemble_6502(lines,pc=0):
objcode = []
symbols = {}
symbols['HIGH'] = lambda x : (x & 0xff00) >> 8
symbols['LOW'] = lambda x : x & 0xff
# Pass 1 : Parse instructions and create intermediate code
for lineno, label, (value, icode) in parse_lines(lines,symbols):
# Try to evaluate numeric labels and set the PC
if label:
try:
pc = int(eval(label,symbols))
except (ValueError,NameError):
symbols[label] = pc
# Store the resulting objcode for later expansion
if icode:
objcode.append((lineno,pc,value,icode))
pc += len(icode)
# Pass 2 : Create final object code by evaluating expressions
execode = []
for lineno, pc, value, icode in objcode:
# Evaluate the value string
try:
symbols['PC'] = pc
realvalue = eval(value,symbols)
if isinstance(realvalue,str):
realvalue = ord(realvalue) & 0xff
if not isinstance(realvalue, int):
raise TypeError("Integer expected in {0}".format(value))
except Exception as e:
print("{0:4d} : Error : {1}".format(lineno,e),file=sys.stderr)
realvalue = 0
ecode = [op(pc,realvalue) if isinstance(op,Callable) else op
for op in icode]
execode.append((lineno,pc,ecode))
return execode
if __name__ == '__main__':
import sys
if len(sys.argv) != 2:
print("Usage %s infile.asm" % sys.argv[0],file=sys.stderr)
raise SystemExit(1)
lines = strip_lines(open(sys.argv[1]))
if 0:
for lineno, pc, opcode in assemble_6502(lines):
print("%04x : " % pc, end="")
print(*(format(op,"02x") for op in opcode))
if 1:
# OSI monitor format
first = 0
lastpc = -1
for lineno, pc, opcode in assemble_6502(lines):
if not first:
first = pc
if lastpc != pc:
print(".%04X/" % pc,end="")
for op in opcode:
print("%02X" % op)
lastpc = pc + len(opcode)
print(".00FB/00")
或許伯克利分校的could be useful，充分說明here
「一點容易的語言」似乎是一年的輕描淡寫...... – Hyperboreus
你說在這裏（http://stackoverflow.com/questions/21288313/assembler-implmentation），你的任務是由於36小時。這仍然是相同的任務或另一個？如果是相同的，請張貼你已經投入的一些努力（一些代碼），有人肯定會幫助你。 – Hyperboreus
@hyperboreus是的，你是對的，但截止日期延遲到星期日下午11:59，這裏是只轉換指令操作部分的代碼： –