Folder restructuring from primedev (#624)v1.21.2-rc3v1.21.2

Copies of over the primedev folder structure for easier cherry-picking of further changes

Co-authored-by: F1F7Y <filip.bartos07@proton.me>

1 files changed, 77 insertions, 0 deletions

diff --git a/primedev/core/structs.h b/primedev/core/structs.h
new file mode 100644
index 00000000..037233a6
--- /dev/null
+++ b/primedev/core/structs.h
@@ -0,0 +1,77 @@
+#pragma once
+//clang-format off
+// About this file:
+// This file contains several macros used to define reversed structs
+// The reason we use these macros is to make it easier to update existing structs
+// when new fields are reversed
+// This means we dont have to manually add padding, and recalculate when updating
+
+// Technical note:
+// While functionally, these structs act like a regular struct, they are actually
+// defined as unions with anonymous structs in them.
+// This means that each field is essentially an offset into a union.
+// We acknowledge that this goes against C++'s active-member guideline for unions
+// However, this is not such a big deal here as these structs will not be constructed
+
+// Usage:
+// To use these macros, define a struct like so:
+/*
+OFFSET_STRUCT(Name)
+{
+	STRUCT_SIZE(0x100)		// Total in-memory struct size
+	FIELD(0x0, int field)	// offset, signature
+}
+*/
+
+#define OFFSET_STRUCT(name) union name
+#define STRUCT_SIZE(size) char __size[size];
+#define STRUCT_FIELD_OFFSET(offset, signature)                                                                                             \
+	struct                                                                                                                                 \
+	{                                                                                                                                      \
+		char CONCAT2(pad, __LINE__)[offset];                                                                                               \
+		signature;                                                                                                                         \
+	};
+
+// Special case for a 0-offset field
+#define STRUCT_FIELD_NOOFFSET(offset, signature) signature;
+
+// Just puts two tokens next to each other, but
+// allows us to force the preprocessor to do another pass
+#define FX(f, x) f x
+
+// Macro used to detect if the given offset is 0 or not
+#define TEST_0 ,
+// MSVC does no preprocessing of integer literals.
+// On other compilers `0x0` gets processed into `0`
+#define TEST_0x0 ,
+
+// Concats the first and third argument and drops everything else
+// Used with preprocessor expansion in later passes to move the third argument to the fourth and change the value
+#define ZERO_P_I(a, b, c, ...) a##c
+
+// We use FX to prepare to use ZERO_P_I.
+// The right block contains 3 arguments:
+// NIF_
+// CONCAT2(TEST_, offset)
+// 1
+//
+// If offset is not 0 (or 0x0) the preprocessor replaces
+// it with nothing and the third argument stays 1
+//
+// If the offset is 0, TEST_0 expands to , and 1 becomes the fourth argument
+//
+// With those arguments we call ZERO_P_I and the first and third arugment get concat.
+// We either end up with:
+// NIF_ (if offset is 0) or
+// NIF_1 (if offset is not 0)
+#define IF_ZERO(m) FX(ZERO_P_I, (NIF_, CONCAT2(TEST_, m), 1))
+
+// These macros are used to branch after we processed if the offset is zero or not
+#define NIF_(t, ...) t
+#define NIF_1(t, ...) __VA_ARGS__
+
+// FIELD(S), generates an anonymous struct when a non 0 offset is given, otherwise just a signature
+#define FIELD(offset, signature) IF_ZERO(offset)(STRUCT_FIELD_NOOFFSET, STRUCT_FIELD_OFFSET)(offset, signature)
+#define FIELDS FIELD
+
+//clang-format on