1 files changed, 100 insertions, 0 deletions
diff --git a/disasm.py b/disasm.py
new file mode 100755
index 0000000..3ba5c2f
--- /dev/null
+++ b/disasm.py
@@ -0,0 +1,100 @@
+#!/usr/bin/env python3
+import sys
+
+mnems = """
+nop
+rot
+nrt
+dup
+swp
+ovr
+drp
+tck
+nip
+equ
+neq
+add
+sub
+mul
+div
+neg
+slt
+ult
+sle
+ule
+lod
+sto
+psh
+pop
+""".split()
+mnems.extend(['???']*(64-len(mnems)))
+def opws(kw):
+	for k in range(16):
+		mnems.append(kw + str(k))
+opws("mark") # who is mark
+opws("loc")
+opws("ret")
+opws("lit")
+
+def dpc(addr):
+	print(f"{addr:04x} | ",end='')
+
+def uuu(b):
+	u=bin(b)[2:].zfill(16)
+	for x in range(0,len(u),4):
+		yield u[x:x+4]
+
+def fbin(b):
+	return '_'.join(uuu(b))
+
+pc = 0
+
+MASK_CALL = 0b1000_0000_0000_0000
+MASK_LIT  = 0b0110_0000_0000_0000
+MASK_JMP  = 0b0100_0000_0000_0000
+def maskeq(x, m):
+	# must be called in the right order
+	return (x&m)==m
+
+def main():
+	while True:
+		global pc
+		bys = sys.stdin.buffer.read(2)
+		if len(bys) < 2: break
+		word = int.from_bytes(bys, 'big')
+		dpc(pc)
+		dpc(word)
+		if maskeq(word, MASK_CALL):
+			disasm_call(word)
+		elif maskeq(word, MASK_LIT):
+			disasm_lit(word)
+		elif maskeq(word, MASK_JMP):
+			disasm_br(word, pc)
+		else:
+			disasm_i(word)
+		pc += 2
+
+def disasm_call(word):
+	addr = word & 0b0111_1111_1111_1111
+	addr = addr << 1
+	print(f"c {addr:04x}")
+def disasm_lit(word):
+	val = word & 0b0001_1111_1111_1111
+	print(f"l {val:04x}")
+def disasm_br(word, pc):
+	is_cond = (word & 0b0001_0000_0000_0000) != 0
+	char = 'b' if is_cond else 'j'
+	rel = (word & 0b0000_1111_1111_1111) - 2048
+	target = rel + pc
+	print(f"{char} {rel:+05x} ={target:04x}")
+def disasm_i(word):
+	opc1 = (word&0b0011_1111_1000_0000)>>7
+	opc2 = (word&0b0000_0000_0111_1111)
+	mnem1 = mnems[opc1]
+	mnem2 = mnems[opc2]
+	if mnem2 == "nop": mnem2 = ""
+	print(f"i {mnem1} {mnem2}")
+
+
+if __name__ == "__main__":
+	main()