text: /*
   * Copyright 2012 Matthew McCormick
   * Copyright 2013 Justin Crawford <Justasic@gmail.com>
   * Copyright 2015 Pawel 'l0ner' Soltys
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  #include <mach/mach.h>
  #include <unistd.h> // usleep()
  
  #include "cpu.h"
  
  uint8_t get_cpu_count()
  {
    return sysconf( _SC_NPROCESSORS_ONLN );
  }
  
  // OSX or BSD based system, use BSD APIs instead
  // See: http://www.opensource.apple.com/source/xnu/xnu-201/osfmk/mach/host_info.h
  // and: http://web.mit.edu/darwin/src/modules/xnu/osfmk/man/
  
  host_cpu_load_info_data_t _get_cpu_percentage()
  {
    kern_return_t              error;
    mach_msg_type_number_t     count;
    host_cpu_load_info_data_t  r_load;
    mach_port_t                mach_port;
  
    count = HOST_CPU_LOAD_INFO_COUNT;
    mach_port = mach_host_self();
    error = host_statistics(mach_port, HOST_CPU_LOAD_INFO, 
        ( host_info_t )&r_load, &count );
  
    if ( error != KERN_SUCCESS )
    {
      return host_cpu_load_info_data_t();
    }
  
    return r_load;
  }
  
  float cpu_percentage( unsigned int cpu_usage_delay )
  {
    // Get the load times from the XNU kernel
    host_cpu_load_info_data_t load1 = _get_cpu_percentage();
    usleep( cpu_usage_delay );
    host_cpu_load_info_data_t load2 = _get_cpu_percentage();
  
    // Current load times
    unsigned long long current_user = load1.cpu_ticks[CP_USER];
    unsigned long long current_system = load1.cpu_ticks[CP_SYS];
    unsigned long long current_nice = load1.cpu_ticks[CP_NICE];
    unsigned long long current_idle = load1.cpu_ticks[CP_IDLE];
    // Next load times
    unsigned long long next_user = load2.cpu_ticks[CP_USER];
    unsigned long long next_system = load2.cpu_ticks[CP_SYS];
    unsigned long long next_nice = load2.cpu_ticks[CP_NICE];
    unsigned long long next_idle = load2.cpu_ticks[CP_IDLE];
    // Difference between the two
    unsigned long long diff_user = next_user - current_user;
    unsigned long long diff_system = next_system - current_system;
    unsigned long long diff_nice = next_nice - current_nice;
    unsigned long long diff_idle = next_idle - current_idle;
  
    return static_cast<float>( diff_user + diff_system + diff_nice ) / 
      static_cast<float>( diff_user + diff_system + diff_nice + diff_idle ) * 
      100.0;
  }
  
  