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authorJack <66967891+ASpoonPlaysGames@users.noreply.github.com>2023-12-27 00:32:01 +0000
committerGitHub <noreply@github.com>2023-12-27 01:32:01 +0100
commitf5ab6fb5e8be7b73e6003d4145081d5e0c0ce287 (patch)
tree90f2c6a4885dbd181799e2325cf33588697674e1 /primedev/core/structs.h
parentbb8ed59f6891b1196c5f5bbe7346cd171c8215fa (diff)
downloadNorthstarLauncher-f5ab6fb5e8be7b73e6003d4145081d5e0c0ce287.tar.gz
NorthstarLauncher-f5ab6fb5e8be7b73e6003d4145081d5e0c0ce287.zip
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>
Diffstat (limited to 'primedev/core/structs.h')
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+#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