Fix MVSC vs MinGW differences in byteswap semantics

Author: cboulay

mock/include/ByteSwap.h

@@ -0,0 +1,26 @@
+#pragma once
+
+// Cross-platform byte swap utilities
+// MSVC uses _byteswap_*, GCC/Clang use __builtin_bswap*
+
+#ifdef _MSC_VER
+#include <cstdlib>  // for _byteswap_*
+
+inline uint16_t bswap16(uint16_t value) { return _byteswap_ushort(value); }
+inline int16_t bswap16(int16_t value) { return static_cast<int16_t>(_byteswap_ushort(static_cast<uint16_t>(value))); }
+inline uint32_t bswap32(uint32_t value) { return _byteswap_ulong(value); }
+inline int32_t bswap32(int32_t value) { return static_cast<int32_t>(_byteswap_ulong(static_cast<uint32_t>(value))); }
+inline uint64_t bswap64(uint64_t value) { return _byteswap_uint64(value); }
+inline int64_t bswap64(int64_t value) { return static_cast<int64_t>(_byteswap_uint64(static_cast<uint64_t>(value))); }
+
+#else
+// GCC/Clang
+
+inline uint16_t bswap16(uint16_t value) { return __builtin_bswap16(value); }
+inline int16_t bswap16(int16_t value) { return static_cast<int16_t>(__builtin_bswap16(static_cast<uint16_t>(value))); }
+inline uint32_t bswap32(uint32_t value) { return __builtin_bswap32(value); }
+inline int32_t bswap32(int32_t value) { return static_cast<int32_t>(__builtin_bswap32(static_cast<uint32_t>(value))); }
+inline uint64_t bswap64(uint64_t value) { return __builtin_bswap64(value); }
+inline int64_t bswap64(int64_t value) { return static_cast<int64_t>(__builtin_bswap64(static_cast<uint64_t>(value))); }
+
+#endif

mock/src/DataStreamGenerator.cpp

@@ -1,4 +1,5 @@
 #include "DataStreamGenerator.h"
+#include "ByteSwap.h"
 #include <chrono>
 #include <cstring>
 #include <iostream>
@@ -166,8 +167,8 @@ void DataStreamGenerator::generateSyntheticData(std::vector<uint8_t>& buffer) {
 
         // Write header (network byte order = big endian)
         AmpDataPacketHeader header;
-        header.ampID = __builtin_bswap64(state.ampId);
-        header.length = __builtin_bswap64(dataSize);
+        header.ampID = bswap64(state.ampId);
+        header.length = bswap64(dataSize);
         std::memcpy(buffer.data(), &header, sizeof(header));
 
         // Generate sample packets
@@ -186,8 +187,8 @@ void DataStreamGenerator::generateSyntheticData(std::vector<uint8_t>& buffer) {
 
         // Write header
         AmpDataPacketHeader header;
-        header.ampID = __builtin_bswap64(state.ampId);
-        header.length = __builtin_bswap64(dataSize);
+        header.ampID = bswap64(state.ampId);
+        header.length = bswap64(dataSize);
         std::memcpy(buffer.data(), &header, sizeof(header));
 
         // Generate sample packets

mock/src/ECIHandler.cpp

@@ -1,4 +1,5 @@
 #include "ECIHandler.h"
+#include "ByteSwap.h"
 #include <cstring>
 #include <iostream>
 
@@ -208,7 +209,7 @@ void ECIHandler::handleNTPReturnSynch(std::shared_ptr<asio::ip::tcp::socket> soc
     // Send back 8-byte NTP time (simplified - just use our sync time)
     int64_t ntpTime = syncTime_;
     if (bigEndian_) {
-        ntpTime = __builtin_bswap64(ntpTime);
+        ntpTime = bswap64(ntpTime);
     }
     asio::write(*socket, asio::buffer(&ntpTime, 8));
 }
@@ -286,14 +287,14 @@ bool ECIHandler::readBytes(std::shared_ptr<asio::ip::tcp::socket> socket, void*
 
 int32_t ECIHandler::swapIfNeeded(int32_t value) const {
     if (bigEndian_) {
-        return __builtin_bswap32(value);
+        return bswap32(value);
     }
     return value;
 }
 
 int16_t ECIHandler::swapIfNeeded(int16_t value) const {
     if (bigEndian_) {
-        return __builtin_bswap16(value);
+        return bswap16(value);
     }
     return value;
 }