commit ff63a59cac215de480e2a751db11c78bef4d2c7c
Author: Loic Nageleisen <loic.nageleisen@gmail.com>
Date:   Thu Apr 5 23:45:16 2012 +0200

    almost there, for an initial impl.
    
    ironically test.py ended up way more advanced than dcpu_16.py

diff --git a/dcpu_16.py b/dcpu_16.py
new file mode 100644
index 0000000..ad94ac7
--- /dev/null
+++ b/dcpu_16.py
@@ -0,0 +1,136 @@
+# System width
+w = 16
+wmask = 2**16-1
+
+# Literal values
+literal = xrange(0x00, 0x20)
+
+opcodes = [
+    'nbi',
+    'SET',
+    'ADD',
+    'SUB',
+    'MUL',
+    'DIV',
+    'MOD',
+    'SHL',
+    'SHR',
+    'AND',
+    'BOR',
+    'XOR',
+    'IFE',
+    'IFN',
+    'IFG',
+    'IFB',
+]
+
+class CPU(object):
+
+    class Ops(object):
+        def SET(c, a, b):
+            return None
+        def ADD(c, a, b):
+            return None
+        def SUB(c, a, b):
+            return None
+        def MUL(c, a, b):
+            return None
+        def DIV(c, a, b):
+            return None
+        def MOD(c, a, b):
+            return None
+        def SHL(c, a, b):
+            return (a << b) & wmask
+        def SHR(c, a, b):
+            return (a >> b)
+        def AND(c, a, b):
+            return a & b
+        def BOR(c, a, b):
+            return a | b
+        def XOR(c, a, b):
+            return a ^ b
+        def IFE(c, a, b):
+            return a == b
+        def IFN(c, a, b):
+            return a != b
+        def IFG(c, a, b):
+            return a > b
+        def IFB(c, a, b):
+            return (a & b) != 0
+
+    def __init__(c):
+        c.reset()
+        c.clear()
+
+    def reset(c):
+        """Reset CPU"""
+        c.r = [0 for _ in xrange(0, w)]
+        c.pc = 0
+        c.sp = 0
+        c.o  = False
+        c.skip = False
+
+    def clear(c):
+        """Clear memory"""
+        c.m = [0 for _ in xrange(0, 2**w)]
+
+    def __getitem__(c, addr):
+        """Read value at memory address"""
+        return c.m[addr]
+
+    def __setitem__(c, addr, value):
+        """Write value at memory address"""
+        c.m[addr] = value
+
+    def next_word(c):
+        val = c[c.pc]
+        c.pc += 1
+        return val
+
+    def dispatch_op(c):
+
+        def get_opcode(word):
+            return word & 0xF
+        def get_a(word):
+            return (word >>  4) & 0x3F
+        def get_b(word):
+            return (word >> 10) & 0x3F
+
+        def get_op(word):
+            getattr(CPU.Ops, opcodes[get_opcode(word)])
+
+        def is_nbi(opcode):
+            return opcode == 0x0
+        def is_set(opcode):
+            return 0x0 < opcode <= 0xb
+        def is_skip(opcode):
+            return 0xb < opcode <= 0xf
+        def set_a(value):
+            pass
+
+        word = c.next_word()
+        if c.skip:
+            c.skip = False
+            return
+
+        opcode = get_opcode(word)
+        if is_nbi(opcode):
+            pass
+        elif is_set(opcode):
+            set_a(get_op(opcode)())
+        elif is_skip(opcode):
+            if not get_op(opcode)():
+                c.skip = True
+        else:
+            raise OpcodeError(c.pc, opcode)
+
+
+
+class OpcodeError(Exception):
+    def __init__(self, addr, data):
+        self.addr = addr
+        self.data = data
+
+    def __str__(self):
+        return "Invalid opcode at %s: '%s'" % (self.addr, self.data)
+
diff --git a/test.py b/test.py
new file mode 100644
index 0000000..e0ebcd8
--- /dev/null
+++ b/test.py
@@ -0,0 +1,364 @@
+from __future__ import print_function, division
+
+def log(string):
+    print(" << %s" % string)
+
+#http://0x10c.com/doc/dcpu-16.txt
+spec = '1.1'
+
+w = 16
+wmask = 2**w-1
+
+literals = [l for l in xrange(0, 0x20)]
+
+opcode_map = {}
+valcode_map = {}
+
+
+class opcode(object):
+    def __init__(self, *opcode):
+        self.opcode = opcode
+
+    def __call__(self, f):
+        _opcode_f = f
+        _opcode_f.opcode = self.opcode
+        opcode_map[self.opcode] = _opcode_f
+        return _opcode_f
+
+
+class valcode(object):
+    def __init__(self, valcode):
+        self.valcode = valcode
+
+    def __call__(self, f):
+        _valcode_f = f
+        _valcode_f.valcode = self.valcode
+        try:
+            for code in self.valcode:
+                # currify with (bound) code
+                valcode_map[code] = lambda c, code=code: _valcode_f(c, code)
+                valcode_map[code].__name__ = '%s(code=0x%02X)' % (_valcode_f.__name__, code)
+        except TypeError:
+            valcode_map[self.valcode] = _valcode_f
+        return _valcode_f
+
+
+@opcode(0x0, 0x01)
+def JSR(c, a):
+    """pushes the address of the next instruction to the stack, then sets PC to a"""
+    #pushnext
+    c.pc = c[a]
+
+@opcode(0x1)
+def SET(c, a, b):
+    """sets a to b"""
+    c[a] = c[b]
+
+@opcode(0x2)
+def ADD(c, a, b):
+    """sets a to a+b, sets O to 0x0001 if there's an overflow"""
+    res = (c[a] + c[b])
+    if res > wmask:
+        c.o = 0x0001
+    res = res & wmask
+    c[a] = res
+
+@opcode(0x3)
+def SUB(c, a, b):
+    """sets a to a-b, sets O to 0xFFFF if there's an underflow"""
+    res = (c[a] - c[b])
+    if res & (wmask+1):
+        c.o = 0xFFFF
+    res = res & wmask
+    c[a] = res
+
+@opcode(0x4)
+def MUL(c, a, b):
+    """sets a to a*b, sets O to ((a*b)>>16)&0xFFFF"""
+    res = (c[a] * c[b])
+    c.o = ((c[a] * c[b]) >> w) & wmask
+    res = res & wmask
+    c[a] = res
+
+@opcode(0x5)
+def DIV(c, a, b):
+    """sets a to a/b, sets O to ((a<<16)/b)&0xFFFF"""
+    res = c[a] / c[b]
+    c.o = ((c[a] << w) / c[b]) & wmask
+    c[a] = res
+
+@opcode(0x6)
+def MOD(c, a, b):
+    """sets a to a%b. if b==0, sets a to 0 instead"""
+    if c[b]==0:
+        res = 0
+    else:
+        res = c[a] % c[b]
+    c[a] = res
+
+@opcode(0x7)
+def SHL(c, a, b):
+    """sets a to a<<b. sets O to ((a<<b)>>16)&0xFFFF"""
+    res = (c[a] << c[b])
+    c.o = ((c[a] << c[b]) >> w) & wmask
+    res = res & wmask
+    c[a] = res
+
+@opcode(0x8)
+def SHR(c, a, b):
+    """sets a to a>>b. sets O to ((a>>16)>>b)&0xFFFF"""
+    res = (c[a] >> c[b])
+    c.o = ((c[a] >> w) >> c[b]) & wmask
+    res = res & wmask
+    c[a] = res
+
+@opcode(0x9)
+def AND(c, a, b):
+    """sets a to a&b"""
+    res = c[a] & c[b]
+    c[a] = res
+
+@opcode(0xA)
+def BOR(c, a, b):
+    """sets a to a|b"""
+    res = c[a] | c[b]
+    c[a] = res
+
+@opcode(0xB)
+def XOR(c, a, b):
+    """sets a to a^b"""
+    res = c[a] ^ c[b]
+    c[a] = res
+
+@opcode(0xC)
+def IFE(c, a, b):
+    """performs next instruction only if a==b"""
+    if c[a] == c[b]:
+        c.skip = True
+
+@opcode(0xD)
+def IFN(c, a, b):
+    """performs next instruction only if a!=b"""
+    if c[a] != c[b]:
+        c.skip = True
+
+@opcode(0xE)
+def IFG(c, a, b):
+    """performs next instruction only if a>b"""
+    if c[a] > c[b]:
+        c.skip = True
+
+@opcode(0xF)
+def IFB(c, a, b):
+    """performs next instruction only if (a&b)!=0"""
+    if (c[a] & c[b]) != 0:
+        c.skip = True
+
+
+def make_pointer(c, codestr):
+    """creates a pointer func that evaluates codestr"""
+    def getter(c=c):
+        return eval("%s" % codestr)
+    def setter(data, c=c):
+        exec("%s = %r" % (codestr, data)) in {}, {'c': c, 'data': data}
+    pointer     = getter
+    pointer.codestr = codestr
+    pointer.set = setter
+    return pointer
+
+def pointerize(f):
+    """wraps a function that generates a codestr to create a pointer"""
+    if f.func_code.co_argcount == 1:
+        ptrz = lambda c: make_pointer(c, f(c))
+    elif f.func_code.co_argcount == 2:
+        ptrz = lambda c, code: make_pointer(c, f(c, code))
+    else:
+        raise Exception('%s has too many arguments' % f.__name__)
+    ptrz.__name__ = 'ptr_to_%s' % f.__name__
+    ptrz.__doc__ = f.__doc__
+    return ptrz
+
+@valcode(range(0x00, 0x08))
+@pointerize
+def register(c, code):
+    """register"""
+    v = "c.r[%r]" % code
+    log(v)
+    return v
+
+@valcode(range(0x08, 0x10))
+@pointerize
+def register_value(c, code):
+    """[register]"""
+    v = "c.m[c.r[%r-0x07]]" % code
+    log(v)
+    return v
+
+@valcode(range(0x10, 0x18))
+@pointerize
+def next_word_plus_register_value(c, code):
+    """[next word + register]"""
+    v = "c.m[%r + %r-0x0f]" % (c.m[c.pc], code)
+    log(v)
+    c.pc += 1
+    return v
+
+@valcode(0x18)
+@pointerize
+def pop(c):
+    """POP / [SP++]"""
+    v = "c.m[%r]" % c.sp
+    log(v)
+    c.sp += 1
+    return v
+
+@valcode(0x19)
+@pointerize
+def peek(c):
+    """PEEK / [SP]"""
+    v = "c.m[%r]" % c.sp
+    log(v)
+    return v
+
+@valcode(0x1A)
+@pointerize
+def push(c):
+    """PUSH / [--SP]"""
+    c.sp -= 1
+    v = "c.m[%r]" % c.sp
+    log(v)
+    return v
+
+@valcode(0x1B)
+@pointerize
+def stack_pointer(c):
+    """stack pointer"""
+    v = "c.sp"
+    log(v)
+    return v
+
+@valcode(0x1C)
+@pointerize
+def program_counter(c):
+    """program counter"""
+    v = "c.pc"
+    log(v)
+    return v
+
+@valcode(0x1D)
+@pointerize
+def overflow(c):
+    """overflow"""
+    v = "c.o"
+    log(v)
+    return v
+
+@valcode(0x1E)
+@pointerize
+def next_word_value(c):
+    """[next_word]"""
+    v = "c.m[%r]" % c.m[c.pc]
+    c.pc += 1
+    log(v)
+    return v
+
+@valcode(0x1F)
+@pointerize
+def next_word(c):
+    """next_word (literal)"""
+    v = "c.m[%r]" % c.pc
+    c.pc += 1
+    log(v)
+    return v
+
+@valcode(range(0x20, 0x40))
+@pointerize
+def literal(c, code):
+    """literal value 0x00-0x1F (literal)"""
+    v = "%r" % (code - 0x20)
+    log(v)
+    return v
+
+
+
+class CPU(object):
+    def __init__(c, debug=False):
+        c.clear()
+        c.reset()
+        c.debug = debug
+
+    def reset(c):
+        """reset CPU"""
+        c.r = [0 for _ in xrange(0, 8)]
+        c.pc = 0x0000
+        c.sp = 0x0000
+        c.o  = 0x0000
+        c.skip = False
+
+    def clear(c):
+        """clear memory"""
+        c.m = [0 for _ in xrange(0, 2**w)]
+
+    def _pointer(c, code):
+        """get pointer to value code"""
+        try:
+            return valcode_map[code](c)
+        except KeyError:
+            raise Exception("Invalid value code")
+
+    def __getitem__(c, code):
+        """get pointer to value"""
+        return c._pointer(code)()
+
+    def __setitem__(c, code, value):
+        """set value at pointer"""
+        c._pointer(code).set(value)
+
+    def step(c):
+        """start handling [PC]"""
+        word = c.m[c.pc]
+        c.pc += 1
+        opcode = word & 0xF
+        try:
+            op = opcode_map[(opcode,)]
+            log(op.__name__)
+        except KeyError:
+            raise Exception('Invalid opcode %01X at PC=%04X' % (opcode, c.pc))
+        a = word >>  4 & 0x3F
+        b = word >> 10 & 0x3F
+        if c.skip:
+            c.skip = False
+        else:
+            op(c, a, b)
+        if c.debug:
+            log(c.dump_r())
+
+    def dump_r(c):
+        """human-readable register status"""
+        return " ".join( "%s=%04X" %
+                (["A", "B", "C",
+                  "X", "Y", "Z",
+                  "I", "J",
+                  "PC", "SP", "O",
+                  ][i],
+                  (c.r + [c.pc, c.sp, c.o])[i])
+                for i in range(11))
+
+    def load_m(c, io=None):
+        """load data in memory"""
+        # TODO: load from io object
+        data = [
+            0x7c01, 0x0030, 0x7de1, 0x1000, 0x0020, 0x7803, 0x1000, 0xc00d,
+            0x7dc1, 0x001a, 0xa861, 0x7c01, 0x2000, 0x2161, 0x2000, 0x8463,
+            0x806d, 0x7dc1, 0x000d, 0x9031, 0x7c10, 0x0018, 0x7dc1, 0x001a,
+            0x9037, 0x61c1, 0x7dc1, 0x001a, 0x0000, 0x0000, 0x0000, 0x0000,
+        ]
+        for i in xrange(len(data)):
+            c.m[i] = data[i]
+
+    def dump_m(c, io):
+        """dump memory data"""
+        # TODO: save to io object
+        pass
+
+