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dmnt-cheat: Support nested conditionals in VM

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This commit is contained in:
Michael Scire 2019-03-05 01:39:20 -08:00
parent 8c86074da2
commit 853a57e4d4
3 changed files with 52 additions and 11 deletions
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57
stratosphere/dmnt/source/dmnt_cheat_vm.cpp
View file

@ -204,6 +204,17 @@ bool DmntCheatVm::DecodeNextOpcode(CheatVmOpcode *out) {
opcode.opcode = (CheatVmOpcodeType)((((u32)opcode.opcode) << 4) | ((first_dword >> 24) & 0xF));
}
/* detect condition start. */
switch (opcode.opcode) {
case CheatVmOpcodeType_BeginConditionalBlock:
case CheatVmOpcodeType_BeginKeypressConditionalBlock:
opcode.begin_conditional_block = true;
break;
default:
opcode.begin_conditional_block = false;
break;
}
switch (opcode.opcode) {
case CheatVmOpcodeType_StoreStatic:
{
@ -357,16 +368,32 @@ bool DmntCheatVm::DecodeNextOpcode(CheatVmOpcode *out) {
}
void DmntCheatVm::SkipConditionalBlock() {
CheatVmOpcode skip_opcode;
while (this->DecodeNextOpcode(&skip_opcode)) {
/* Decode instructions until we see end of conditional block. */
/* NOTE: This is broken in gateway's implementation. */
/* Gateway currently checks for "0x2" instead of "0x20000000" */
/* In addition, they do a linear scan instead of correctly decoding opcodes. */
/* This causes issues if "0x2" appears as an immediate in the conditional block... */
if (skip_opcode.opcode == CheatVmOpcodeType_EndConditionalBlock) {
break;
if (this->condition_depth > 0) {
/* We want to continue until we're out of the current block. */
size_t desired_depth = this->condition_depth - 1;
CheatVmOpcode skip_opcode;
while (this->DecodeNextOpcode(&skip_opcode) && this->condition_depth > desired_depth) {
/* Decode instructions until we see end of the current conditional block. */
/* NOTE: This is broken in gateway's implementation. */
/* Gateway currently checks for "0x2" instead of "0x20000000" */
/* In addition, they do a linear scan instead of correctly decoding opcodes. */
/* This causes issues if "0x2" appears as an immediate in the conditional block... */
/* We also support nesting of conditional blocks, and Gateway does not. */
if (skip_opcode.begin_conditional_block) {
this->condition_depth++;
} else if (skip_opcode.opcode == CheatVmOpcodeType_EndConditionalBlock) {
this->condition_depth--;
}
}
} else {
/* Skipping, but this->condition_depth = 0. */
/* This is an error condition. */
/* However, I don't actually believe it is possible for this to happen. */
/* I guess we'll throw a fatal error here, so as to encourage me to fix the VM */
/* in the event that someone triggers it? I don't know how you'd do that. */
fatalSimple(ResultDmntCheatVmInvalidCondDepth);
}
}
@ -402,6 +429,7 @@ void DmntCheatVm::ResetState() {
this->loop_tops[i] = 0;
}
this->instruction_ptr = 0;
this->condition_depth = 0;
this->decode_success = true;
}
@ -452,6 +480,11 @@ void DmntCheatVm::Execute(const CheatProcessMetadata *metadata) {
}
this->LogOpcode(&cur_opcode);
/* Increment conditional depth, if relevant. */
if (cur_opcode.begin_conditional_block) {
this->condition_depth++;
}
switch (cur_opcode.opcode) {
case CheatVmOpcodeType_StoreStatic:
{
@ -511,7 +544,11 @@ void DmntCheatVm::Execute(const CheatProcessMetadata *metadata) {
}
break;
case CheatVmOpcodeType_EndConditionalBlock:
/* There is nothing to do here. Just move on to the next instruction. */
/* Decrement the condition depth. */
/* We will assume, graciously, that mismatched conditional block ends are a nop. */
if (this->condition_depth > 0) {
this->condition_depth--;
}
break;
case CheatVmOpcodeType_ControlLoop:
if (cur_opcode.ctrl_loop.start_loop) {

2
stratosphere/dmnt/source/dmnt_cheat_vm.hpp
View file

@ -164,6 +164,7 @@ struct StoreRegisterToAddressOpcode {
struct CheatVmOpcode {
CheatVmOpcodeType opcode;
bool begin_conditional_block;
union {
StoreStaticOpcode store_static;
BeginConditionalOpcode begin_cond;
@ -186,6 +187,7 @@ class DmntCheatVm {
private:
size_t num_opcodes = 0;
size_t instruction_ptr = 0;
size_t condition_depth = 0;
bool decode_success = false;
u32 program[MaximumProgramOpcodeCount] = {0};
u64 registers[NumRegisters] = {0};

2
stratosphere/dmnt/source/dmnt_results.hpp
View file

@ -34,3 +34,5 @@ static constexpr Result ResultDmntCheatInvalidFreezeWidth = MAKERESULT(Modul
static constexpr Result ResultDmntCheatAddressAlreadyFrozen = MAKERESULT(Module_Dmnt, 6601);
static constexpr Result ResultDmntCheatAddressNotFrozen = MAKERESULT(Module_Dmnt, 6602);
static constexpr Result ResultDmntCheatTooManyFrozenAddresses = MAKERESULT(Module_Dmnt, 6603);
static constexpr Result ResultDmntCheatVmInvalidCondDepth = MAKERESULT(Module_Dmnt, 6700);