Add a fully implementation of endian.h

include/endian.h

@@ -0,0 +1,91 @@
+// Copyright (c) 2026 Quoc Trung (https://github.com/thisisaname1928)
+// This software is released under the GNU General Public License v3.0. See
+// LICENSE file for details. This header needs to maintain in any file it is
+// present in, as per the GPL license terms.
+#ifndef ENDIAN_H
+#define ENDIAN_H
+
+#include <stdint.h>
+
+// PDP_ENDIAN too old, no need to implement it
+#define LITTLE_ENDIAN 1234
+#define BIG_ENDIAN 4321
+
+#if defined(__BYTE_ORDER__)
+#define __LIBC_BYTE_ORDER __BYTE_ORDER__
+#elif defined(__BYTE_ORDER)
+#define __LIBC_BYTE_ORDER __BYTE_ORDER
+#endif
+
+// manually detect byte order
+#if !defined(__BYTE_ORDER__) && !defined(__BYTE_ORDER)
+#if defined(__x86_64__) || defined(__i386__) || defined(_M_IX86)
+#define __LIBC_BYTE_ORDER LITTLE_ENDIAN
+#elif defined(__powerpc__) || defined(__m68k__)
+#define __LIBC_BYTE_ORDER BIG_ENDIAN
+#else
+#error "BoredOS libc doesn't support this architecture!"
+#endif
+#endif
+
+#if defined(_MSC_VER)
+#define __bswap16(x) _byteswap_ushort(x)
+#define __bswap32(x) _byteswap_ulong(x)
+#define __bswap64(x) _byteswap_uint64(x)
+#elif defined(__GNUC__) || defined(__clang__)
+#define __bswap16(x) __builtin_bswap16(x)
+#define __bswap32(x) __builtin_bswap32(x)
+#define __bswap64(x) __builtin_bswap64(x)
+#else
+#define __bswap16(x) (uint16_t)(((uint16_t)(x) << 8) | ((uint16_t)(x) >> 8))
+#define __bswap32(x)                                                           \
+  (uint32_t)((((uint32_t)(x) >> 24) & 0xff) |                                  \
+             (((uint32_t)(x) >> 8) & 0xff00) |                                 \
+             (((uint32_t)(x) << 8) & 0xff0000) |                               \
+             (((uint32_t)(x) << 24) & 0xff000000))
+#define __bswap64(x)                                                           \
+  (uint64_t)((((uint64_t)(x) >> 56) & 0x00000000000000ffULL) |                 \
+             (((uint64_t)(x) >> 40) & 0x000000000000ff00ULL) |                 \
+             (((uint64_t)(x) >> 24) & 0x0000000000ff0000ULL) |                 \
+             (((uint64_t)(x) >> 8) & 0x00000000ff000000ULL) |                  \
+             (((uint64_t)(x) << 8) & 0x000000ff00000000ULL) |                  \
+             (((uint64_t)(x) << 24) & 0x0000ff0000000000ULL) |                 \
+             (((uint64_t)(x) << 40) & 0x00ff000000000000ULL) |                 \
+             (((uint64_t)(x) << 56) & 0xff00000000000000ULL))
+#endif
+
+#if (__LIBC_BYTE_ORDER == LITTLE_ENDIAN)
+#define be16toh(x) (__bswap16(x))
+#define be32toh(x) (__bswap32(x))
+#define be64toh(x) (__bswap64(x))
+
+#define htobe16(x) (__bswap16(x))
+#define htobe32(x) (__bswap32(x))
+#define htobe64(x) (__bswap64(x))
+
+#define htole16(x) ((uint16_t)(x))
+#define htole32(x) ((uint32_t)(x))
+#define htole64(x) ((uint64_t)(x))
+
+#define le16toh(x) ((uint16_t)(x))
+#define le32toh(x) ((uint32_t)(x))
+#define le64toh(x) ((uint64_t)(x))
+#else
+#define be16toh(x) ((uint16_t)(x))
+#define be32toh(x) ((uint32_t)(x))
+#define be64toh(x) ((uint64_t)(x))
+
+#define htobe16(x) ((uint16_t)(x))
+#define htobe32(x) ((uint32_t)(x))
+#define htobe64(x) ((uint64_t)(x))
+
+#define htole16(x) (__bswap16(x))
+#define htole32(x) (__bswap32(x))
+#define htole64(x) (__bswap64(x))
+
+#define le16toh(x) (__bswap16(x))
+#define le32toh(x) (__bswap32(x))
+#define le64toh(x) (__bswap64(x))
+#endif
+
+#endif