本文共 5241 字，大约阅读时间需要 17 分钟。

下面的代码是从 CUB中摘录出来的。

/** * Utility for parsing command line arguments */struct CommandLineArgs{    std::vector
   
        keys;    std::vector
    
         values;    std::vector
     
          args;    cudaDeviceProp              deviceProp;    float                       device_giga_bandwidth;    size_t                      device_free_physmem;    size_t                      device_total_physmem;    /**     * Constructor     */    CommandLineArgs(int argc, char **argv) :        keys(10),        values(10)    {        using namespace std;        // Initialize mersenne generator        unsigned int mersenne_init[4]=  {0x123, 0x234, 0x345, 0x456};        mersenne::init_by_array(mersenne_init, 4);        for (int i = 1; i < argc; i++)        {            string arg = argv[i];            if ((arg[0] != '-') || (arg[1] != '-'))            {                args.push_back(arg);                continue;            }            string::size_type pos;            string key, val;            if ((pos = arg.find('=')) == string::npos) {                key = string(arg, 2, arg.length() - 2);                val = "";            } else {                key = string(arg, 2, pos - 2);                val = string(arg, pos + 1, arg.length() - 1);            }            keys.push_back(key);            values.push_back(val);        }    }    /**     * Checks whether a flag "--
      
       " is present in the commandline     */    bool CheckCmdLineFlag(const char* arg_name)    {        using namespace std;        for (int i = 0; i < int(keys.size()); ++i)        {            if (keys[i] == string(arg_name))                return true;        }        return false;    }    /**     * Returns number of naked (non-flag and non-key-value) commandline parameters     */    template 
       
            int NumNakedArgs()    {        return args.size();    }    /**     * Returns the commandline parameter for a given index (not including flags)     */    template 
        
          void GetCmdLineArgument(int index, T &val) { using namespace std; if (index < args.size()) { istringstream str_stream(args[index]); str_stream >> val; } } /** * Returns the value specified for a given commandline parameter --
         
          =
          
            */ template 
           
             void GetCmdLineArgument(const char *arg_name, T &val) { using namespace std; for (int i = 0; i < int(keys.size()); ++i) { if (keys[i] == string(arg_name)) { istringstream str_stream(values[i]); str_stream >> val; } } } /** * Returns the values specified for a given commandline parameter --
            
             =
             
              ,
              
               * */ template 
               
                 void GetCmdLineArguments(const char *arg_name, std::vector
                
                  &vals) { using namespace std; if (CheckCmdLineFlag(arg_name)) { // Clear any default values vals.clear(); // Recover from multi-value string for (int i = 0; i < keys.size(); ++i) { if (keys[i] == string(arg_name)) { string val_string(values[i]); istringstream str_stream(val_string); string::size_type old_pos = 0; string::size_type new_pos = 0; // Iterate comma-separated values T val; while ((new_pos = val_string.find(',', old_pos)) != string::npos) { if (new_pos != old_pos) { str_stream.width(new_pos - old_pos); str_stream >> val; vals.push_back(val); } // skip over comma str_stream.ignore(1); old_pos = new_pos + 1; } // Read last value str_stream >> val; vals.push_back(val); } } } } /** * The number of pairs parsed */ int ParsedArgc() { return (int) keys.size(); } /** * Initialize device */ cudaError_t DeviceInit(int dev = -1) { cudaError_t error = cudaSuccess; do { int deviceCount; error = CubDebug(cudaGetDeviceCount(&deviceCount)); if (error) break; if (deviceCount == 0) { fprintf(stderr, "No devices supporting CUDA.\n"); exit(1); } if (dev < 0) { GetCmdLineArgument("device", dev); } if ((dev > deviceCount - 1) || (dev < 0)) { dev = 0; } error = CubDebug(cudaSetDevice(dev)); if (error) break; CubDebugExit(cudaMemGetInfo(&device_free_physmem, &device_total_physmem)); int ptx_version; error = CubDebug(cub::PtxVersion(ptx_version)); if (error) break; error = CubDebug(cudaGetDeviceProperties(&deviceProp, dev)); if (error) break; if (deviceProp.major < 1) { fprintf(stderr, "Device does not support CUDA.\n"); exit(1); } device_giga_bandwidth = float(deviceProp.memoryBusWidth) * deviceProp.memoryClockRate * 2 / 8 / 1000 / 1000; if (!CheckCmdLineFlag("quiet")) { printf( "Using device %d: %s (PTX version %d, SM%d, %d SMs, " "%lld free / %lld total MB physmem, " "%.3f GB/s @ %d kHz mem clock, ECC %s)\n", dev, deviceProp.name, ptx_version, deviceProp.major * 100 + deviceProp.minor * 10, deviceProp.multiProcessorCount, (unsigned long long) device_free_physmem / 1024 / 1024, (unsigned long long) device_total_physmem / 1024 / 1024, device_giga_bandwidth, deviceProp.memoryClockRate, (deviceProp.ECCEnabled) ? "on" : "off"); fflush(stdout); } } while (0); return error; }};
                
               
              
             
            
           
          
         
        
       
      
     
    
   

使用：

int mian(int argc,char *argv){    int num_items = 150;    // Initialize command line    CommandLineArgs args(argc, argv);    g_verbose = args.CheckCmdLineFlag("v");    args.GetCmdLineArgument("n", num_items);    // Print usage    if (args.CheckCmdLineFlag("help"))    {        printf("%s "               "[--n= "               "[--device=
   
    ] "               "[--v] "               "\n", argv[0]);        exit(0);    }return 0;}
   

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