Refactor: internalize endianness macros and simplify MD5 implementation

- oapv_port.h: Introduce cross-platform endianness swap and conversion macros (OAPV_SWAP*, OAPV_LE32_TO_CPU).

- oapv_util.c: Replace manual byte swapping with new macros in MD5 transform to improve readability and maintainability.

- Standardize endianness handling across the codebase.

Signed-off-by: Anemptyship <hanbin1931@gmail.com>

Author: Anemptyship

src/oapv_port.h

@@ -203,5 +203,51 @@ static __inline void oapv_mset_16b(s16 *dst, s16 v, int cnt)
 /* CPU information */
 int oapv_get_num_cpu_cores(void);
 
+/* Endianness handling */
+#if defined(__GNUC__) || defined(__clang__)
+#define OAPV_SWAP16(x) __builtin_bswap16(x)
+#define OAPV_SWAP32(x) __builtin_bswap32(x)
+#define OAPV_SWAP64(x) __builtin_bswap64(x)
+#elif defined(_MSC_VER)
+#define OAPV_SWAP16(x) _byteswap_ushort(x)
+#define OAPV_SWAP32(x) _byteswap_ulong(x)
+#define OAPV_SWAP64(x) _byteswap_uint64(x)
+#else
+#define OAPV_SWAP16(x) ((((x) & 0xff00) >> 8) | (((x) & 0x00ff) << 8))
+#define OAPV_SWAP32(x) ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >> 8) | \
+                        (((x) & 0x0000ff00) << 8)  | (((x) & 0x000000ff) << 24))
+#define OAPV_SWAP64(x) ((((x) & 0xff00000000000000ull) >> 56) | \
+                        (((x) & 0x00ff000000000000ull) >> 40) | \
+                        (((x) & 0x0000ff0000000000ull) >> 24) | \
+                        (((x) & 0x000000ff00000000ull) >> 8)  | \
+                        (((x) & 0x00000000ff000000ull) << 8)  | \
+                        (((x) & 0x0000000000ff0000ull) << 24) | \
+                        (((x) & 0x000000000000ff00ull) << 40) | \
+                        (((x) & 0x00000000000000ffull) << 56))
+#endif
+
+#if defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
+#define OAPV_BIG_ENDIAN 1
+#define OAPV_CPU_TO_LE32(x) OAPV_SWAP32(x)
+#define OAPV_CPU_TO_LE64(x) OAPV_SWAP64(x)
+#define OAPV_LE32_TO_CPU(x) OAPV_SWAP32(x)
+#define OAPV_LE64_TO_CPU(x) OAPV_SWAP64(x)
+#define OAPV_CPU_TO_BE32(x) (x)
+#define OAPV_CPU_TO_BE64(x) (x)
+#define OAPV_BE32_TO_CPU(x) (x)
+#define OAPV_BE64_TO_CPU(x) (x)
+#else
+// Little Endian (Default for x86/ARM)
+#define OAPV_LITTLE_ENDIAN 1
+#define OAPV_CPU_TO_LE32(x) (x)
+#define OAPV_CPU_TO_LE64(x) (x)
+#define OAPV_LE32_TO_CPU(x) (x)
+#define OAPV_LE64_TO_CPU(x) (x)
+#define OAPV_CPU_TO_BE32(x) OAPV_SWAP32(x)
+#define OAPV_CPU_TO_BE64(x) OAPV_SWAP64(x)
+#define OAPV_BE32_TO_CPU(x) OAPV_SWAP32(x)
+#define OAPV_BE64_TO_CPU(x) OAPV_SWAP64(x)
+#endif
+
 #endif /* _OAPV_PORT_H_ */
 

src/oapv_util.c

@@ -44,17 +44,16 @@ static void md5_trans(u32 *buf, const u8 *msg)
 {
     register u32 a, b, c, d;
 
-#if defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)
-    const u32 *blk = (const u32 *)msg;
-#else
+#if OAPV_BIG_ENDIAN
     u32 x[16];
     int i;
-
+    const u32 *ptr = (const u32 *)msg;
     for (i = 0; i < 16; i++) {
-        x[i] = ((u32)msg[i*4+0]) | (((u32)msg[i*4+1]) << 8) | 
-               (((u32)msg[i*4+2]) << 16) | (((u32)msg[i*4+3]) << 24);
+         x[i] = OAPV_LE32_TO_CPU(ptr[i]);
     }
     const u32 *blk = x;
+#else // Little Endian
+    const u32 *blk = (const u32 *)msg;
 #endif
 
     a = buf[0];