write a portable version of endian.h, to replace the system's endian.h.

utilising GNU C standard library for some of the functionality, or GNU C
extensions.

include/endian.h

@@ -1,9 +1,45 @@
 /* Copyright (c) 2025 Quinn
  * Licensed under the MIT Licence. See LICENSE for details */
-#pragma once
 
-#if __has_include(<endian.h>)
+#ifndef PORTABLE_ENDIAN_H
-#include <endian.h>
+#define PORTABLE_ENDIAN_H 1
+
+#if defined(__GNUC__)
+
+/* test for the byteswap header */
+#if __has_include(<byteswap.h>)
+#include <byteswap.h>
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+#define le16toh(x) (x)
+#define le32toh(x) (x)
+#define le64toh(x) (x)
+#define htole16(x) (x)
+#define htole32(x) (x)
+#define htole64(x) (x)
+#define be16toh(x) __bswap_16(x)
+#define be32toh(x) __bswap_32(x)
+#define be64toh(x) __bswap_64(x)
+#define htobe16(x) __bswap_16(x)
+#define htobe32(x) __bswap_32(x)
+#define htobe64(x) __bswap_64(x)
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+#define le16toh(x) __bswap_16(x)
+#define le32toh(x) __bswap_32(x)
+#define le64toh(x) __bswap_64(x)
+#define htole16(x) __bswap_16(x)
+#define htole32(x) __bswap_32(x)
+#define htole64(x) __bswap_64(x)
+#define be16toh(x) (x)
+#define be32toh(x) (x)
+#define be64toh(x) (x)
+#define htobe16(x) (x)
+#define htobe32(x) (x)
+#define htobe64(x) (x)
+#else
+#error machine architecture unsupported! Expected either big-endian or little-endian, make sure to use a compiler which defines __BYTE_ORDER__ (like clang or gcc)
+#endif /* byte order */
+
+/* otherwise, utilise the compiler built-ins */
 #else
 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
 #define le16toh(x) __uint16_identity(x)
@@ -33,5 +69,12 @@
 #define htobe64(x) __uint64_identity(x)
 #else
 #error machine architecture unsupported! Expected either big-endian or little-endian, make sure to use a compiler which defines __BYTE_ORDER__ (like clang or gcc)
-#endif
+#endif /* byte order */
-#endif
+
+#endif /* has byteswap.h */
+
+#else
+#error GNU C is unavailable
+#endif /* __GNUC__ */
+
+#endif /* PORTABLE_ENDIAN_H */

makefile

@@ -51,7 +51,7 @@ PROF = rel
 CFLAGS += -DNDEBUG -O2
 endif
 
-CFLAGS  += $(shell pkg-config --cflags glfw3 libarchive) -Ilib/glad/include
+CFLAGS  += $(shell pkg-config --cflags glfw3 libarchive) -Iinclude -Ilib/glad/include
 LDFLAGS += $(shell pkg-config --libs glfw3 libarchive) -lm
 
 # get source files

src/dat/mcx.c

@@ -3,12 +3,12 @@
 #include "mcx.h"
 
 #include <assert.h>
+#include <endian.h>
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
 
-#include "../util/compat/endian.h"
 #include "../util/intdef.h"
 
 #define TABLE  0x2000 // table byte size

src/dat/nbt.c

@@ -3,11 +3,11 @@
 #include "nbt.h"
 
 #include <assert.h>
+#include <endian.h>
 #include <stddef.h>
 #include <stdlib.h>
 #include <string.h>
 
-#include "../util/compat/endian.h"
 #include "../util/intdef.h"
 
 #define MAX_DEPTH 512

src/dat/nbt.h

@@ -3,11 +3,11 @@
 #pragma once
 
 #include <assert.h>
+#include <endian.h>
 #include <stdbool.h>
 #include <stdlib.h>
 
 #include "../util/atrb.h"
-#include "../util/compat/endian.h"
 #include "../util/intdef.h"
 
 /* NBT (named binary tag) is a tree data structure. Tags have a numeric type ID, name and a payload.