First release of open-appsec source code

components/include/byteorder.h

@@ -0,0 +1,48 @@
+#ifndef __BYTEORDER_H__
+#define __BYTEORDER_H__
+
+// Byte Order (Net-to-Host, Host-to-Net) operations
+//
+// C provides htons, ntohs, htonl, ntohl, but they're not "constexpr" so are unusable in case labels.
+// C++ proposal N3620 adds some function, but it's not accepted (yet?). It uses templates which are,
+//  IMO, a bit complicated so I chose not to adapt it.
+
+static inline constexpr uint16_t
+constHTONS(uint16_t h_ord)
+{
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+    return ((h_ord>>8) & 0xff) |
+        ((h_ord&0xff) << 8);
+#elif __BYTE_ORDER == __BIG_ENDIAN
+    return h_ord;
+#else
+#error unknown byte order
+#endif // __BYTE_ORDER
+}
+
+static inline constexpr uint16_t
+constNTOHS(uint16_t n_ord)
+{
+    return constHTONS(n_ord);    // Same thing
+}
+
+static inline constexpr uint32_t
+constHTONL(uint32_t h_ord)
+{
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+    return ((constHTONS(h_ord>>16)) & 0xffff) |
+        ((constHTONS(h_ord&0xffff)) << 16);
+#elif __BYTE_ORDER == __BIG_ENDIAN
+    return h_ord;
+#else
+#error unknown byte order
+#endif // __BYTE_ORDER
+}
+
+static inline constexpr uint32_t
+constNTOHL(uint32_t n_ord)
+{
+    return constHTONL(n_ord);    // Same thing
+}
+
+#endif // __BYTEORDER_H__