From a529a16822e69627cd896585ffbdec63612ab68f Mon Sep 17 00:00:00 2001
From: Kawe Mazidjatari <48657826+Mauler125@users.noreply.github.com>
Date: Sat, 27 Jan 2024 01:36:29 +0100
Subject: [PATCH] RTech: add helpers for parsing patch header data

Should significantly reduce noise in code
---
 r5dev/rtech/pak/paktools.cpp | 42 ++++++++++++++++++++++++++++++++++++
 r5dev/rtech/pak/paktools.h   |  4 ++++
 2 files changed, 46 insertions(+)

diff --git a/r5dev/rtech/pak/paktools.cpp b/r5dev/rtech/pak/paktools.cpp
index 3900b125..c30f9199 100644
--- a/r5dev/rtech/pak/paktools.cpp
+++ b/r5dev/rtech/pak/paktools.cpp
@@ -145,3 +145,45 @@ const PakLoadedInfo_t* Pak_GetPakInfo(const char* const pakName)
 	Warning(eDLL_T::RTECH, "%s - Failed to retrieve pak info for name '%s'\n", __FUNCTION__, pakName);
 	return nullptr;
 }
+
+//-----------------------------------------------------------------------------
+// returns a pointer to the patch data header
+//-----------------------------------------------------------------------------
+PakPatchDataHeader_t* Pak_GetPatchDataHeader(PakFileHeader_t* const pakHeader)
+{
+	// shouldn't be called if the pak doesn1't have patches!
+	assert(pakHeader->patchIndex > 0);
+	return reinterpret_cast<PakPatchDataHeader_t*>(reinterpret_cast<uint8_t* const>(pakHeader) + sizeof(PakFileHeader_t));
+}
+
+//-----------------------------------------------------------------------------
+// returns a pointer to the patch file header
+//-----------------------------------------------------------------------------
+PakPatchFileHeader_t* Pak_GetPatchFileHeader(PakFileHeader_t* const pakHeader, const int index)
+{
+	assert(pakHeader->patchIndex > 0 && index < pakHeader->patchIndex);
+	uint8_t* address = reinterpret_cast<uint8_t* const>(pakHeader);
+
+	// skip the file header
+	address += sizeof(PakFileHeader_t);
+
+	// skip the patch data header, the patch file headers start from there
+	address += sizeof(PakPatchDataHeader_t);
+	PakPatchFileHeader_t* const patchHeaders = reinterpret_cast<PakPatchFileHeader_t* const>(address);
+
+	return &patchHeaders[index];
+}
+
+//-----------------------------------------------------------------------------
+// returns the patch number belonging to the index provided
+//-----------------------------------------------------------------------------
+short Pak_GetPatchNumberForIndex(PakFileHeader_t* const pakHeader, const int index)
+{
+	const uint8_t* patchHeader = reinterpret_cast<const uint8_t*>(Pak_GetPatchFileHeader(pakHeader, pakHeader->patchIndex - 1));
+
+	// skip the last patch file header, the patch number start from there
+	patchHeader += sizeof(PakPatchFileHeader_t);
+	const short* patchNumber = reinterpret_cast<const short*>(patchHeader);
+
+	return patchNumber[index];
+}
diff --git a/r5dev/rtech/pak/paktools.h b/r5dev/rtech/pak/paktools.h
index af32e13c..1755781f 100644
--- a/r5dev/rtech/pak/paktools.h
+++ b/r5dev/rtech/pak/paktools.h
@@ -11,4 +11,8 @@ extern PakGuid_t Pak_StringToGuid(const char* const string);
 extern const PakLoadedInfo_t* Pak_GetPakInfo(const PakHandle_t pakId);
 extern const PakLoadedInfo_t* Pak_GetPakInfo(const char* const pakName);
 
+extern PakPatchDataHeader_t* Pak_GetPatchDataHeader(PakFileHeader_t* const pakHeader);
+extern PakPatchFileHeader_t* Pak_GetPatchFileHeader(PakFileHeader_t* const pakHeader, const int index);
+extern short Pak_GetPatchNumberForIndex(PakFileHeader_t* const pakHeader, const int index);
+
 #endif // !RTECH_PAKTOOLS_H