From a75d9c67819e3a26269ce489c83f1978b1297a5e Mon Sep 17 00:00:00 2001
From: Maurizio Porrato <maurizio.porrato@gmail.com>
Date: Sat, 25 Jan 2020 10:31:08 +0000
Subject: [PATCH] Added simple disassembler

---
 disasm.py | 72 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100755 disasm.py

diff --git a/disasm.py b/disasm.py
new file mode 100755
index 0000000..a2adb3f
--- /dev/null
+++ b/disasm.py
@@ -0,0 +1,72 @@
+#!/usr/bin/env python3
+
+import struct
+
+
+OPCODES = (
+    None , 'SET', 'ADD', 'SUB', 'MUL', 'MLI', 'DIV', 'DVI',
+    'MOD', 'MDI', 'AND', 'BOR', 'XOR', 'SHR', 'ASR', 'SHL',
+    'IFB', 'IFC', 'IFE', 'IFN', 'IFG', 'IFA', 'IFL', 'IFU',
+    None , None , 'ADX', 'SBX', None , None , 'STI', 'STD'
+)
+
+OPCODES_X = (
+    None , 'JSR', None , None , None , None , None , None ,
+    'INT', 'IAG', 'IAS', 'RFI', 'IAQ', None , None , None ,
+    'HWN', 'HWQ', 'HWI', None , None , None , None , None ,
+    None , None , None , None , None , None , None , None
+)
+
+ADDRESSING = (
+    'A', 'B', 'C', 'X', 'Y', 'Z', 'I', 'J',
+    '[A]', '[B]', '[C]', '[X]', '[Y]', '[Z]', '[I]', '[J]',
+    '[A+n]', '[B+n]', '[C+n]', '[X+n]', '[Y+n]', '[Z+n]', '[I+n]', '[J+n]',
+    'POP/PUSH', 'PEEK', 'PEEK n', 'SP', 'PC', 'EX', '[n]', 'n'
+)
+
+def read_word(f):
+    b = f.read(2)
+    if len(b) < 2:
+        raise EOFError()
+    return struct.unpack("<H", b)[0]
+
+def disassemble(filename):
+    with open(filename, 'rb') as f:
+        pc = 0
+        while True:
+            try:
+                w = read_word(f)
+            except EOFError:
+                break
+            ins = [w]
+            op = w & 0x1f
+            b = (w >> 5) & 0x1f
+            a = (w >> 10) & 0x3f
+            if a < 0x20:
+                a_str = ADDRESSING[a]
+                if 'n' in a_str:
+                    w = read_word(f)
+                    ins.append(w)
+                    a_str = a_str.replace('n', str(w))
+            else:
+                a_str = str(int(a) - 0x21)
+            a_str = a_str.split('/')[0]
+            if op == 0:
+                mnemonic = "%s %s" % (OPCODES_X[b], a_str)
+            else:
+                b_str = ADDRESSING[b]
+                if 'n' in b_str:
+                    w = read_word(f)
+                    ins.append(w)
+                    b_str = b_str.replace('n', str(w))
+                b_str = b_str.split('/')[-1]
+                mnemonic = "%s %s, %s" % (OPCODES[op], b_str, a_str)
+            print("%5d:\t%-20s; %s" % (pc, mnemonic, ' '.join(["%04x" % x for x in ins])))
+            pc += len(ins)
+
+
+if __name__ == '__main__':
+    import sys
+
+    if len(sys.argv) > 1:
+        disassemble(sys.argv[1])