Throw an exception if an illegal device or platform index is specified

platforms/cuda/src/CudaContext.cpp

@@ -120,7 +120,9 @@ CudaContext::CudaContext(const System& system, int deviceIndex, bool useBlocking
     int numDevices;
     string errorMessage = "Error initializing Context";
     CHECK_RESULT(cuDeviceGetCount(&numDevices));
-    if (deviceIndex < 0 || deviceIndex >= numDevices) {
+    if (deviceIndex < -1 || deviceIndex >= numDevices)
+        throw OpenMMException("Illegal value for CudaDeviceIndex: "+intToString(deviceIndex));
+    if (deviceIndex == -1) {
         // Try to figure out which device is the fastest.
 
         int bestSpeed = -1;

platforms/opencl/src/OpenCLContext.cpp

@@ -89,23 +89,27 @@ OpenCLContext::OpenCLContext(const System& system, int platformIndex, int device
         contextIndex = platformData.contexts.size();
         std::vector<cl::Platform> platforms;
         cl::Platform::get(&platforms);
+        if (platformIndex < -1 || platformIndex >= (int) platforms.size())
+            throw OpenMMException("Illegal value for OpenCLPlatformIndex: "+intToString(platformIndex));
         const int minThreadBlockSize = 32;
 
         int bestSpeed = -1;
         int bestDevice = -1;
         int bestPlatform = -1;
         for (int j = 0; j < platforms.size(); j++) {
-            // if they supplied a valid platformIndex, we only look through that platform
-            if (j != platformIndex && platformIndex >= 0 && platformIndex < (int) platforms.size())
+            // If they supplied a valid platformIndex, we only look through that platform
+            if (j != platformIndex && platformIndex != -1)
                 continue;
 
             string platformVendor = platforms[j].getInfo<CL_PLATFORM_VENDOR>();
             vector<cl::Device> devices;
             platforms[j].getDevices(CL_DEVICE_TYPE_ALL, &devices);
+            if (deviceIndex < -1 || deviceIndex >= (int) devices.size())
+                throw OpenMMException("Illegal value for OpenCLDeviceIndex: "+intToString(deviceIndex));
 
             for (int i = 0; i < (int) devices.size(); i++) {
-                // if they supplied a valid deviceIndex, we only look through that one
-                if (i != deviceIndex && deviceIndex >= 0 && deviceIndex < (int) devices.size())
+                // If they supplied a valid deviceIndex, we only look through that one
+                if (i != deviceIndex && deviceIndex != -1)
                     continue;
                 if (platformVendor == "Apple" && (devices[i].getInfo<CL_DEVICE_TYPE>() == CL_DEVICE_TYPE_CPU))
                     continue; // The CPU device on OS X won't work correctly.