From 477bee2e4ca0960a579bcd3a285d026f86dacbce Mon Sep 17 00:00:00 2001
From: Michael Scire <SciresM@gmail.com>
Date: Thu, 4 Apr 2019 12:16:00 -0700
Subject: [PATCH] dmnt-cheat: Add Save/Restore register opcode

---
 stratosphere/dmnt/source/dmnt_cheat_vm.cpp | 32 ++++++++++++++++++++++
 stratosphere/dmnt/source/dmnt_cheat_vm.hpp |  8 ++++++
 2 files changed, 40 insertions(+)

diff --git a/stratosphere/dmnt/source/dmnt_cheat_vm.cpp b/stratosphere/dmnt/source/dmnt_cheat_vm.cpp
index 7aef982c9..cc1c3820f 100644
--- a/stratosphere/dmnt/source/dmnt_cheat_vm.cpp
+++ b/stratosphere/dmnt/source/dmnt_cheat_vm.cpp
@@ -188,6 +188,12 @@ void DmntCheatVm::LogOpcode(const CheatVmOpcode *opcode) {
                         break;
                 }
             break;
+        case CheatVmOpcodeType_SaveRestoreRegister: 
+            this->LogToDebugFile("Opcode: Save or Restore Register\n");
+            this->LogToDebugFile("Dst Idx:   %x\n", opcode->save_restore_reg.dst_index);
+            this->LogToDebugFile("Src Idx:   %x\n", opcode->save_restore_reg.src_index);
+            this->LogToDebugFile("Is Save:   %d\n", opcode->save_restore_reg.is_save);
+            break;
         default:
             this->LogToDebugFile("Unknown opcode: %x\n", opcode->opcode);
             break;
@@ -462,6 +468,19 @@ bool DmntCheatVm::DecodeNextOpcode(CheatVmOpcode *out) {
                 }
             }
             break;
+        case CheatVmOpcodeType_SaveRestoreRegister:
+            {
+                /* C10D0Sx0 */
+                /* C1 = opcode 0xC1 */
+                /* D = destination index. */
+                /* S = source index. */
+                /* x = 1 if saving a register, 0 if restoring a register. */
+                /* NOTE: If we add more save slots later, current encoding is backwards compatible. */
+                opcode.save_restore_reg.dst_index = (first_dword >> 16) & 0xF;
+                opcode.save_restore_reg.src_index = (first_dword >> 8) & 0xF;
+                opcode.save_restore_reg.is_save = ((first_dword >> 4) & 0xF) != 0;
+            }
+            break;
         case CheatVmOpcodeType_ExtendedWidth:
         default:
             /* Unrecognized instruction cannot be decoded. */
@@ -532,6 +551,7 @@ u64 DmntCheatVm::GetCheatProcessAddress(const CheatProcessMetadata* metadata, Me
 void DmntCheatVm::ResetState() {
     for (size_t i = 0; i < DmntCheatVm::NumRegisters; i++) {
         this->registers[i] = 0;
+        this->saved_values[i] = 0;
         this->loop_tops[i] = 0;
     }
     this->instruction_ptr = 0;
@@ -585,6 +605,10 @@ void DmntCheatVm::Execute(const CheatProcessMetadata *metadata) {
         for (size_t i = 0; i < NumRegisters; i++) {
             this->LogToDebugFile("Registers[%02x]: %016lx\n", i, this->registers[i]);
         }
+
+        for (size_t i = 0; i < NumRegisters; i++) {
+            this->LogToDebugFile("SavedRegs[%02x]: %016lx\n", i, this->saved_values[i]);
+        }
         this->LogOpcode(&cur_opcode);
         
         /* Increment conditional depth, if relevant. */
@@ -964,6 +988,14 @@ void DmntCheatVm::Execute(const CheatProcessMetadata *metadata) {
                     }
                 }
                 break;
+            case CheatVmOpcodeType_SaveRestoreRegister:
+                /* Save or restore a register. */
+                if (cur_opcode.save_restore_reg.is_save) {
+                    this->saved_values[cur_opcode.save_restore_reg.dst_index] = this->registers[cur_opcode.save_restore_reg.src_index];
+                } else {
+                    this->registers[cur_opcode.save_restore_reg.dst_index] = this->saved_values[cur_opcode.save_restore_reg.src_index];
+                }
+                break;
             default:
                 /* By default, we do a no-op. */
                 break;
diff --git a/stratosphere/dmnt/source/dmnt_cheat_vm.hpp b/stratosphere/dmnt/source/dmnt_cheat_vm.hpp
index 4140a6251..5689f8fd8 100644
--- a/stratosphere/dmnt/source/dmnt_cheat_vm.hpp
+++ b/stratosphere/dmnt/source/dmnt_cheat_vm.hpp
@@ -43,6 +43,7 @@ enum CheatVmOpcodeType : u32 {
     
     /* Extended width opcodes. */
     CheatVmOpcodeType_BeginRegisterConditionalBlock = 0xC0,
+    CheatVmOpcodeType_SaveRestoreRegister = 0xC1,
 };
 
 enum MemoryAccessType : u32 {
@@ -191,6 +192,11 @@ struct BeginRegisterConditionalOpcode {
     VmInt value;
 };
 
+struct SaveRestoreRegisterOpcode {
+    u32 dst_index;
+    u32 src_index;
+    bool is_save;
+};
 
 struct CheatVmOpcode {
     CheatVmOpcodeType opcode;
@@ -208,6 +214,7 @@ struct CheatVmOpcode {
         PerformArithmeticRegisterOpcode perform_math_reg;
         StoreRegisterToAddressOpcode str_register;
         BeginRegisterConditionalOpcode begin_reg_cond;
+        SaveRestoreRegisterOpcode save_restore_reg;
     };
 };
 
@@ -222,6 +229,7 @@ class DmntCheatVm {
         bool decode_success = false;
         u32 program[MaximumProgramOpcodeCount] = {0};
         u64 registers[NumRegisters] = {0};
+        u64 saved_values[NumRegisters] = {0};
         size_t loop_tops[NumRegisters] = {0};
     private:
         bool DecodeNextOpcode(CheatVmOpcode *out);