macos doesn't support endian.h

Author: pfeatherstone

src/http_async.h

@@ -1,6 +1,5 @@
 #pragma once
 
-#include <endian.h>
 #include <boost/asio/version.hpp>
 #include <boost/asio/compose.hpp>
 #include <boost/asio/read.hpp>
@@ -149,6 +148,66 @@ namespace http
 
     namespace details
     {
+
+//----------------------------------------------------------------------------------------------------------------
+
+        constexpr uint16_t byte_swap16(uint16_t v)
+        {
+            return static_cast<uint16_t>(((v & 0x00FF) << 8) | ((v & 0xFF00) >> 8));
+        }
+
+        constexpr uint32_t byte_swap32(uint32_t v)
+        {
+            return static_cast<uint32_t>(((v & 0x000000FF) << 24) |
+                                         ((v & 0x0000FF00) << 8)  |
+                                         ((v & 0x00FF0000) >> 8)  |
+                                         ((v & 0xFF000000) >> 24));
+        }
+
+        constexpr uint64_t byte_swap64(uint64_t v)
+        {
+            return static_cast<uint64_t>(((v & 0x00000000000000FFULL) << 56) |
+                                         ((v & 0x000000000000FF00ULL) << 40) |
+                                         ((v & 0x0000000000FF0000ULL) << 24) |
+                                         ((v & 0x00000000FF000000ULL) << 8)  |
+                                         ((v & 0x000000FF00000000ULL) >> 8)  |
+                                         ((v & 0x0000FF0000000000ULL) >> 24) |
+                                         ((v & 0x00FF000000000000ULL) >> 40) |
+                                         ((v & 0xFF00000000000000ULL) >> 56));
+        }
+
+        static_assert(byte_swap16(0x1234)               == 0x3412,              "bad swap");
+        static_assert(byte_swap32(0x12345678)           == 0x78563412,          "bad swap");
+        static_assert(byte_swap64(0x123456789abcdef1)   == 0xf1debc9a78563412,  "bad swap");
+
+//----------------------------------------------------------------------------------------------------------------
+        
+        inline bool is_little_endian() 
+        {
+            constexpr uint32_t v{0x01020304};
+            const auto*        ptr{reinterpret_cast<const unsigned char*>(&v)};
+            return ptr[0] == 0x04;
+        }
+
+//----------------------------------------------------------------------------------------------------------------
+   
+        inline uint16_t host_to_b16(uint16_t v)
+        {
+            return is_little_endian() ? byte_swap16(v) : v;
+        }
+
+        inline uint32_t host_to_b32(uint32_t v)
+        {
+            return is_little_endian() ? byte_swap32(v) : v;
+        }
+
+        inline uint64_t host_to_b64(uint64_t v)
+        {
+            return is_little_endian() ? byte_swap64(v) : v;
+        }
+
+//----------------------------------------------------------------------------------------------------------------
+   
         template<class AsyncReadStream, class Message>
         struct async_http_read_impl
         {
@@ -701,14 +760,14 @@ namespace http
 
             if (hdr.paylen == 126)
             {
-                uint16_t len = htobe16((uint16_t)pay_len);
+                uint16_t len = host_to_b16((uint16_t)pay_len);
                 memcpy(&buf[off], &len, 2);
                 off += 2;
             }
 
             else if (hdr.paylen == 127)
             {
-                uint64_t len = htobe64((uint64_t)pay_len);
+                uint64_t len = host_to_b64((uint64_t)pay_len);
                 memcpy(&buf[off], &len, 8);
                 off += 8;
             }