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Preprocess cheats to get rid of hacks that try to modify the cheat engine, add support for C2 cheat opcode

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Gericom
2026-03-14 12:27:35 +01:00
parent 8c8f36f5c6
commit d0f25a51d9
5 changed files with 142 additions and 3 deletions
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80
arm7/source/loader/CheatPreprocessor.cpp Normal file
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#include "common.h"
#include <iterator>
#include <algorithm>
#include <span>
#include "CheatPreprocessor.h"
// Based on original code by edo9300: https://github.com/edo9300/nitrohax-usercheat-supercard/blob/master/arm9/source/cheat.cpp.
static constexpr u64 NOP = 0x00000000D4000000;
static constexpr u64 D4_ORR_HACK = 0xE1833004023FE424;
static constexpr u64 D4_AND_HACK = 0xE0033004023FE424;
static constexpr u64 D4_ADD_HACK = 0xE0833004023FE424;
static constexpr u64 DB_CODE_FIX_HACK = 0x0A000003023FE4D8;
// Make 0x0E handler execute the data as arm
static constexpr u64 ASM_HACK_START = 0x012FFF11023FE074;
// Restore behaviour of 0x0E handler
static constexpr u64 ASM_HACK_END = 0xE3520003023FE074;
void CheatPreprocessor::PreprocessCheat(pload_cheat_t* cheat) const
{
PatchD4Hack(cheat, D4_ORR_HACK, 0x1);
PatchD4Hack(cheat, D4_AND_HACK, 0x2);
PatchD4Hack(cheat, D4_ADD_HACK, 0x0);
PatchDBFix(cheat);
PatchAsmHack(cheat);
}
void CheatPreprocessor::PatchD4Hack(pload_cheat_t* cheat, u64 hackPattern, u8 patchedInstructionFlag) const
{
std::span<u64> u64Data((u64*)cheat->opcodes, cheat->length / sizeof(u64));
auto start = std::ranges::find(u64Data, hackPattern);
if (start != u64Data.end())
{
*start++ = NOP;
auto end = std::find(start, u64Data.end(), D4_ADD_HACK);
auto it = std::find_if(start, end, [] (auto elem) { return (elem & 0xFFFFFFFF) == 0xD4000000; });
if (it != end)
{
// Replace 0xD4 code with nitrohax's custom operator code
*it |= patchedInstructionFlag;
}
if (end != u64Data.end())
{
*end++ = NOP;
}
}
}
void CheatPreprocessor::PatchDBFix(pload_cheat_t* cheat) const
{
std::span<u64> u64Data((u64*)cheat->opcodes, cheat->length / sizeof(u64));
auto start = std::ranges::find(u64Data, DB_CODE_FIX_HACK);
if (start != u64Data.end())
{
*start++ = NOP;
}
}
void CheatPreprocessor::PatchAsmHack(pload_cheat_t* cheat) const
{
// Make the asm cheats designed for ards work with nitrohax
std::span<u64> u64Data((u64*)cheat->opcodes, cheat->length / sizeof(u64));
auto start = std::ranges::find(u64Data, ASM_HACK_START);
if (start != u64Data.end())
{
*start++ = NOP;
auto end = std::find(start, u64Data.end(), ASM_HACK_END);
auto it = std::find_if(start, end, [] (auto elem) { return (elem & 0xFFFFFFFF) == 0xE0000000; });
if (it != end)
{
// Replace 0x0E code with nitrohax's 0xC2 in arm mode (0xXXXXXXXXE0000000 - 0xXXXXXXXX1E000000 = 0xXXXXXXXXC2000000)
*it -= 0x1E000000;
}
if (end != u64Data.end())
{
*end++ = NOP;
}
}
}