From bb7fbcda6c8174dc91d4880759247a18a3a7be60 Mon Sep 17 00:00:00 2001
From: Chris Pressey <cpressey@catseye.tc>
Date: Fri, 16 Oct 2015 22:59:35 +0100
Subject: [PATCH] Add Emitter framework, and 6502 Generator (will likely
 change.)

---
 src/sixtypical/emitter.py | 65 ++++++++++++++++++++++++++++
 src/sixtypical/gen6502.py | 91 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 156 insertions(+)
 create mode 100644 src/sixtypical/emitter.py
 create mode 100644 src/sixtypical/gen6502.py

diff --git a/src/sixtypical/emitter.py b/src/sixtypical/emitter.py
new file mode 100644
index 0000000..53456bf
--- /dev/null
+++ b/src/sixtypical/emitter.py
@@ -0,0 +1,65 @@
+class Word(object):
+    def __init__(self, value):
+        self.value = value
+
+    def size(self):
+        return 2
+
+    def serialize(self):
+        word = self.value
+        low = word & 255
+        high = (word >> 8) & 255
+        return chr(low) + chr(high)
+
+
+class Label(object):
+    def __init__(self, name, addr=None):
+        self.name = name
+        self.addr = addr
+
+    def set_addr(self, addr):
+        self.addr = addr
+
+    def size(self):
+        return 2
+
+    def serialize(self):
+        if self.addr is None:
+            raise ValueError(self.addr)
+        return Word(self.addr).serialize()
+
+
+class Emitter(object):
+    def __init__(self, addr):
+        self.accum = []
+        self.addr = addr
+        self.name_counter = 0
+
+    def gen(self, *things):
+        for thing in things:
+            if isinstance(thing, int):
+                if thing < -127 or thing > 255:
+                    raise ValueError(thing)
+                if thing < 0:
+                    thing += 256
+                self.accum.append(thing)
+                self.addr += 1
+            else:
+                self.accum.append(thing)
+                self.addr += thing.size()
+
+    def serialize(self, stream):
+        for thing in self.accum:
+            if isintance(thing, int):
+                stream.write(chr(thing))
+            else:
+                stream.write(thing.serialize())
+
+    def make_label(self, name=None):
+        if name is None:
+            name = 'label' + self.name_counter
+            self.name_counter += 1
+        return Label(name, addr=self.addr)
+
+    def resolve_label(self, label):
+        label.set_addr(self.addr)
diff --git a/src/sixtypical/gen6502.py b/src/sixtypical/gen6502.py
new file mode 100644
index 0000000..47831ef
--- /dev/null
+++ b/src/sixtypical/gen6502.py
@@ -0,0 +1,91 @@
+"""This is just a sketch for now."""
+
+from sixtypical.emitter import Emitter, Word, Label
+
+
+class Generator(object):
+    def __init__(self, addr):
+        self.emitter = Emitter(addr)
+
+    ### ld ###
+
+    def gen_lda_imm(self, b):
+        self.emitter.emit(0xa9, b)
+
+    def gen_lda_abs(self, addr):
+        self.emitter.emit(0xad, addr)
+
+    def gen_ldx_imm(self, b):
+        self.emitter.emit(0xa2, b)
+
+    def gen_ldx_abs(self, addr):
+        self.emitter.emit(0xae, addr)
+
+    def gen_tax(self):
+        self.emitter.emit(0xaa)
+
+    def gen_tay(self):
+        self.emitter.emit(0xa8)
+
+    def gen_txa(self):
+        self.emitter.emit(0x8a)
+
+    def gen_tya(self):
+        self.emitter.emit(0x98)
+
+    ### st ###
+
+    def gen_sta_abs(self, addr):
+        self.emitter.emit(0x8d, addr)
+
+    def gen_stx_abs(self, addr):
+        self.emitter.emit(0x8e, addr)
+
+    def gen_sty_abs(self, addr):
+        self.emitter.emit(0x8c, addr)
+
+    ### add ###
+
+    def gen_adc_imm(self, b):
+        self.emitter.emit(0x69, b)
+
+    def gen_adc_abs(self, addr):
+        self.emitter.emit(0x6d, addr)
+
+    ### sub ###
+
+    def gen_sbc_imm(self, b):
+        self.emitter.emit(0xe9, b)
+
+    def gen_sbc_abs(self, addr):
+        self.emitter.emit(0xed, addr)
+
+    ### inc ###
+
+    def gen_inc_abs(self, addr):
+        self.emitter.emit(0xee, addr)
+
+    def gen_inx(self):
+        self.emitter.emit(0xe8)
+
+    def gen_iny(self):
+        self.emitter.emit(0xc8)
+
+    ### dec ###
+
+    def gen_dec_abs(self, addr):
+        self.emitter.emit(0xce, addr)
+
+    def gen_dex(self):
+        self.emitter.emit(0xca)
+
+    def gen_dey(self):
+        self.emitter.emit(0x88)
+
+    ### and ###
+
+    def gen_and_imm(self, b):
+        self.emitter.emit(0x29, b)
+
+    def gen_and_abs(self, addr):
+        self.emitter.emit(0x2d, addr)