Move latency timer updates to openPort() function

src/main/c/Windows/SerialPort_Windows.c

@@ -272,7 +272,7 @@ JNIEXPORT jobjectArray JNICALL Java_com_fazecast_jSerialComm_SerialPort_getCommP
 									break;
 								}
 
-						// Update the port description and latency if not already open
+						// Update the port description if not already open
 						if (!isOpen)
 						{
 							LONG comPortNumber = 0;
@@ -284,85 +284,6 @@ JNIEXPORT jobjectArray JNICALL Java_com_fazecast_jSerialComm_SerialPort_getCommP
 								for (int j = 0; j < serialPorts.length; ++j)
 									if (wcscmp(serialPorts.ports[j]->portPath, comPort) == 0)
 									{
-										// Reduce the port's latency timer to minimum value of 2
-										HKEY key, paramKey = 0;
-										if (RegOpenKeyExW(HKEY_LOCAL_MACHINE, L"SYSTEM\\CurrentControlSet\\Enum\\FTDIBUS", 0, KEY_READ, &key) == ERROR_SUCCESS)
-										{
-											DWORD index = 0, latency = 2, subkeySize = 255, portNameSize = 16, oldLatency = 2, oldLatencySize = sizeof(DWORD);
-											wchar_t *subkey = (wchar_t*)malloc(subkeySize*sizeof(wchar_t)), *regPortName = (wchar_t*)malloc(portNameSize*sizeof(wchar_t));
-											while (RegEnumKeyExW(key, index++, subkey, &subkeySize, NULL, NULL, NULL, NULL) == ERROR_SUCCESS)
-											{
-												char *subkeyString = (char*)malloc(subkeySize);
-												memset(subkeyString, 0, subkeySize);
-												wcstombs(subkeyString, subkey, subkeySize);
-												subkeySize = 255;
-												portNameSize = 16;
-												memset(regPortName, 0, portNameSize * sizeof(wchar_t));
-												wcscat_s(subkey, subkeySize, L"\\0000\\Device Parameters");
-												if (RegOpenKeyExW(key, subkey, 0, KEY_QUERY_VALUE, &paramKey) == ERROR_SUCCESS)
-												{
-													if ((RegQueryValueExW(paramKey, L"PortName", NULL, NULL, (LPBYTE)regPortName, &portNameSize) == ERROR_SUCCESS) && (wcscmp(serialPorts.ports[j]->portPath, regPortName) == 0))
-														RegQueryValueExW(paramKey, L"LatencyTimer", NULL, NULL, (LPBYTE)&oldLatency, &oldLatencySize);
-													RegCloseKey(paramKey);
-												}
-												if (oldLatency > latency)
-												{
-													if (RegOpenKeyExW(key, subkey, 0, KEY_SET_VALUE, &paramKey) == ERROR_SUCCESS)
-													{
-														RegSetValueExW(paramKey, L"LatencyTimer", 0, REG_DWORD, (LPBYTE)&latency, sizeof(latency));
-														RegCloseKey(paramKey);
-													}
-													else
-													{
-														// Create registry update file
-														char *workingDirectory = _getcwd(NULL, 0);
-														wchar_t *workingDirectoryWide = _wgetcwd(NULL, 0);
-														int workingDirectoryLength = strlen(workingDirectory) + 1;
-														char *registryFileName = (char*)malloc(workingDirectoryLength + 8);
-														wchar_t *paramsString = (wchar_t*)malloc((workingDirectoryLength + 11) * sizeof(wchar_t));
-														sprintf(registryFileName, "%s\\del.reg", workingDirectory);
-														swprintf(paramsString, workingDirectoryLength + 11, L"/s %s\\del.reg", workingDirectoryWide);
-														FILE *registryFile = fopen(registryFileName, "wb");
-														if (registryFile)
-														{
-															fprintf(registryFile, "Windows Registry Editor Version 5.00\n\n");
-															fprintf(registryFile, "[HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\Enum\\FTDIBUS\\%s\\0000\\Device Parameters]\n", subkeyString);
-															fprintf(registryFile, "\"LatencyTimer\"=dword:00000002\n\n");
-															fclose(registryFile);
-														}
-
-														// Launch a new administrative process to update the registry value
-														SHELLEXECUTEINFOW shExInfo = { 0 };
-														shExInfo.cbSize = sizeof(shExInfo);
-														shExInfo.fMask = SEE_MASK_NOCLOSEPROCESS;
-														shExInfo.hwnd = NULL;
-														shExInfo.lpVerb = L"runas";
-														shExInfo.lpFile = L"C:\\Windows\\regedit.exe";
-														shExInfo.lpParameters = paramsString;
-														shExInfo.lpDirectory = NULL;
-														shExInfo.nShow = SW_SHOW;
-														shExInfo.hInstApp = 0;
-														if (ShellExecuteExW(&shExInfo))
-														{
-															WaitForSingleObject(shExInfo.hProcess, INFINITE);
-															CloseHandle(shExInfo.hProcess);
-														}
-
-														// Delete the registry update file
-														remove(registryFileName);
-														free(workingDirectoryWide);
-														free(workingDirectory);
-														free(registryFileName);
-														free(paramsString);
-													}
-												}
-												free(subkeyString);
-											}
-											RegCloseKey(key);
-											free(regPortName);
-											free(subkey);
-										}
-
 										// Update the port description
 										serialPorts.ports[j]->enumerated = 1;
 										size_t descLength = 8+strlen(devInfo[i].Description);
@@ -523,6 +444,86 @@ JNIEXPORT jlong JNICALL Java_com_fazecast_jSerialComm_SerialPort_openPortNative(
 		return 0;
 	}
 
+	// Reduce the port's latency timer to minimum value of 2
+	HKEY key, paramKey = 0;
+	if (RegOpenKeyExW(HKEY_LOCAL_MACHINE, L"SYSTEM\\CurrentControlSet\\Enum\\FTDIBUS", 0, KEY_READ, &key) == ERROR_SUCCESS)
+	{
+		DWORD index = 0, subkeySize = 255, portNameSize = 16;
+		wchar_t *subkey = (wchar_t*)malloc(subkeySize*sizeof(wchar_t)), *regPortName = (wchar_t*)malloc(portNameSize*sizeof(wchar_t));
+		while (RegEnumKeyExW(key, index++, subkey, &subkeySize, NULL, NULL, NULL, NULL) == ERROR_SUCCESS)
+		{
+			DWORD latency = 2, oldLatency = 2, oldLatencySize = sizeof(DWORD);
+			char *subkeyString = (char*)malloc(subkeySize + 2);
+			memset(subkeyString, 0, subkeySize + 2);
+			wcstombs(subkeyString, subkey, subkeySize + 1);
+			subkeySize = 255;
+			portNameSize = 16;
+			memset(regPortName, 0, portNameSize * sizeof(wchar_t));
+			wcscat_s(subkey, subkeySize, L"\\0000\\Device Parameters");
+			if (RegOpenKeyExW(key, subkey, 0, KEY_QUERY_VALUE, &paramKey) == ERROR_SUCCESS)
+			{
+				if ((RegQueryValueExW(paramKey, L"PortName", NULL, NULL, (LPBYTE)regPortName, &portNameSize) == ERROR_SUCCESS) && (wcscmp(port->portPath + 4, regPortName) == 0))
+					RegQueryValueExW(paramKey, L"LatencyTimer", NULL, NULL, (LPBYTE)&oldLatency, &oldLatencySize);
+				RegCloseKey(paramKey);
+			}
+			if (oldLatency > latency)
+			{
+				if (RegOpenKeyExW(key, subkey, 0, KEY_SET_VALUE, &paramKey) == ERROR_SUCCESS)
+				{
+					RegSetValueExW(paramKey, L"LatencyTimer", 0, REG_DWORD, (LPBYTE)&latency, sizeof(latency));
+					RegCloseKey(paramKey);
+				}
+				else
+				{
+					// Create registry update file
+					char *workingDirectory = _getcwd(NULL, 0);
+					wchar_t *workingDirectoryWide = _wgetcwd(NULL, 0);
+					int workingDirectoryLength = strlen(workingDirectory) + 1;
+					char *registryFileName = (char*)malloc(workingDirectoryLength + 8);
+					wchar_t *paramsString = (wchar_t*)malloc((workingDirectoryLength + 11) * sizeof(wchar_t));
+					sprintf(registryFileName, "%s\\del.reg", workingDirectory);
+					swprintf(paramsString, workingDirectoryLength + 11, L"/s %s\\del.reg", workingDirectoryWide);
+					FILE *registryFile = fopen(registryFileName, "wb");
+					if (registryFile)
+					{
+						fprintf(registryFile, "Windows Registry Editor Version 5.00\n\n");
+						fprintf(registryFile, "[HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\Enum\\FTDIBUS\\%s\\0000\\Device Parameters]\n", subkeyString);
+						fprintf(registryFile, "\"LatencyTimer\"=dword:00000002\n\n");
+						fclose(registryFile);
+					}
+
+					// Launch a new administrative process to update the registry value
+					SHELLEXECUTEINFOW shExInfo = { 0 };
+					shExInfo.cbSize = sizeof(shExInfo);
+					shExInfo.fMask = SEE_MASK_NOCLOSEPROCESS;
+					shExInfo.hwnd = NULL;
+					shExInfo.lpVerb = L"runas";
+					shExInfo.lpFile = L"C:\\Windows\\regedit.exe";
+					shExInfo.lpParameters = paramsString;
+					shExInfo.lpDirectory = NULL;
+					shExInfo.nShow = SW_SHOW;
+					shExInfo.hInstApp = 0;
+					if (ShellExecuteExW(&shExInfo))
+					{
+						WaitForSingleObject(shExInfo.hProcess, INFINITE);
+						CloseHandle(shExInfo.hProcess);
+					}
+
+					// Delete the registry update file
+					remove(registryFileName);
+					free(workingDirectoryWide);
+					free(workingDirectory);
+					free(registryFileName);
+					free(paramsString);
+				}
+			}
+			free(subkeyString);
+		}
+		RegCloseKey(key);
+		free(regPortName);
+		free(subkey);
+	}
+
 	// Try to open the serial port with read/write access
 	if ((port->handle = CreateFileW(portName, GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_FLAG_NO_BUFFERING | FILE_FLAG_WRITE_THROUGH | FILE_FLAG_OVERLAPPED, NULL)) != INVALID_HANDLE_VALUE)
 	{