From d4907eb204bb86f9a83d7c805f3bd58320f9278d Mon Sep 17 00:00:00 2001
From: Forest Belton <65484+forestbelton@users.noreply.github.com>
Date: Tue, 3 Aug 2021 19:28:18 -0400
Subject: [PATCH] Implement operand mutation

---
 ex.py                        | 21 +--------------------
 gbso/cpu/insn.py             |  3 +++
 gbso/program/mutate.py       | 27 +++++++++++++++++++--------
 tests/program/test_mutate.py |  3 +++
 4 files changed, 26 insertions(+), 28 deletions(-)

diff --git a/ex.py b/ex.py
index d2d4476..66da56d 100644
--- a/ex.py
+++ b/ex.py
@@ -1,16 +1,8 @@
 from gbso.cpu.insn import *
 from gbso.cpu.regs import R8, R16
 
-from gbso.optimize import (
-    DEFAULT_PROB_INSN,
-    DEFAULT_PROB_INSN_UNUSED,
-    DEFAULT_PROB_OPCODE,
-    DEFAULT_PROB_OPERAND,
-    DEFAULT_PROB_SWAP,
-    optimize,
-)
+from gbso.optimize import optimize
 from gbso.program.program import Program
-from gbso.program.mutate import mutate_program
 
 rLCDC = 0xFF40
 rIE = 0xFFFF
@@ -30,14 +22,3 @@ prgm = Program(
 
 optimized_prgm = optimize(prgm)
 optimized_prgm.display()
-
-for _ in range(10):
-    prgm = mutate_program(
-        prgm,
-        prob_opcode=DEFAULT_PROB_OPCODE,
-        prob_operand=DEFAULT_PROB_OPERAND,
-        prob_swap=DEFAULT_PROB_SWAP,
-        prob_insn=DEFAULT_PROB_INSN,
-        prob_insn_unused=DEFAULT_PROB_INSN_UNUSED,
-    )
-    prgm.display()
diff --git a/gbso/cpu/insn.py b/gbso/cpu/insn.py
index 6c4f2e2..9e557ff 100644
--- a/gbso/cpu/insn.py
+++ b/gbso/cpu/insn.py
@@ -1047,6 +1047,9 @@ class DEC_HL(Insn):
         return "DEC (HL)"
 
 
+# TODO: Implement DAA
+
+
 @dataclass
 class CPL(Insn):
     @staticmethod
diff --git a/gbso/program/mutate.py b/gbso/program/mutate.py
index 0b87bc1..1ce64e1 100644
--- a/gbso/program/mutate.py
+++ b/gbso/program/mutate.py
@@ -1,9 +1,10 @@
+from dataclasses import replace
 from enum import Enum
-from gbso.cpu.regs import R16, R16_WITHOUT_SP, R8
 from random import choice, randint, random, randrange
 from typing import List, Tuple, Type, TypeVar, Union
 
 from gbso.cpu.insn import ALL_INSN_CLASSES, Insn, Operand, UNUSED, get_signature_class
+from gbso.cpu.regs import R16, R16_WITHOUT_SP, R8
 from gbso.program.program import Program
 
 
@@ -31,19 +32,16 @@ def mutate_program(
         ]
     )
     new_prgm = prgm
-    print("======")
+
     if mutation == Mutation.OPCODE:
-        print("OPCODE")
         new_prgm = mutate_opcode(prgm)
     elif mutation == Mutation.OPERAND:
-        print("OPERAND")
         new_prgm = mutate_operand(prgm)
     elif mutation == Mutation.SWAP:
-        print("SWAP")
         new_prgm = mutate_swap(prgm)
     elif mutation == Mutation.INSTRUCTION:
-        print("INSN")
         new_prgm = mutate_insn(prgm, prob_insn_unused)
+
     return new_prgm
 
 
@@ -57,9 +55,22 @@ def mutate_opcode(prgm: Program) -> Program:
     return Program(insns=insns)
 
 
-# TODO: Implement
+# God, this is ugly... a better approach would be to store operands as a tuple
+# instead of individual named fields.
 def mutate_operand(prgm: Program) -> Program:
-    return prgm
+    insn_index = randrange(len(prgm.insns))
+    insn = prgm.insns[insn_index]
+
+    operand_index = randrange(len(insn.signature()))
+    operand_type = insn.signature()[operand_index]
+    operand_name = list(vars(insn).keys())[operand_index]
+
+    insns = prgm.insns.copy()
+    insns[insn_index] = replace(
+        insn, **{operand_name: create_random_operand(operand_type)}
+    )
+
+    return Program(insns=insns)
 
 
 def mutate_swap(prgm: Program) -> Program:
diff --git a/tests/program/test_mutate.py b/tests/program/test_mutate.py
index 473cb99..33605b5 100644
--- a/tests/program/test_mutate.py
+++ b/tests/program/test_mutate.py
@@ -1,6 +1,9 @@
 from gbso.cpu.insn import ADD_A_N, ADD_A_R, DEC_HL, LD_RR_NN
 from gbso.program.mutate import *
 
+# NOTE: All of these trial counts and probabilities could be a lot more precise,
+# but it is easier to just throw extra trials at the problem.
+
 
 def test_mutate_swap():
     trials = 1000