text: 
  #include "BatteryMeter.h"
  
  #include <CoreFoundation/CoreFoundation.h>
  #include <CoreFoundation/CFString.h>
  #include <IOKit/ps/IOPowerSources.h>
  #include <IOKit/ps/IOPSKeys.h>
  
  void Battery_getData(double* level, ACPresence* isOnAC) {
     CFTypeRef power_sources = IOPSCopyPowerSourcesInfo();
  
     *level = -1;
     *isOnAC = AC_ERROR;
  
     if(NULL == power_sources) {
        return;
     }
  
     if(power_sources != NULL) {
        CFArrayRef list = IOPSCopyPowerSourcesList(power_sources);
        CFDictionaryRef battery = NULL;
        int len;
  
        if(NULL == list) {
           CFRelease(power_sources);
  
           return;
        }
  
        len = CFArrayGetCount(list);
  
        /* Get the battery */
        for(int i = 0; i < len && battery == NULL; ++i) {
           CFDictionaryRef candidate = IOPSGetPowerSourceDescription(power_sources,
                                       CFArrayGetValueAtIndex(list, i)); /* GET rule */
           CFStringRef type;
  
           if(NULL != candidate) {
              type = (CFStringRef) CFDictionaryGetValue(candidate,
                     CFSTR(kIOPSTransportTypeKey)); /* GET rule */
  
              if(kCFCompareEqualTo == CFStringCompare(type, CFSTR(kIOPSInternalType), 0)) {
                 CFRetain(candidate);
                 battery = candidate;
              }
           }
        }
  
        if(NULL != battery) {
           /* Determine the AC state */
           CFStringRef power_state = CFDictionaryGetValue(battery, CFSTR(kIOPSPowerSourceStateKey));
  
           *isOnAC = (kCFCompareEqualTo == CFStringCompare(power_state, CFSTR(kIOPSACPowerValue), 0))
                   ? AC_PRESENT
                   : AC_ABSENT;
  
           /* Get the percentage remaining */
           double current;
           double max;
  
           CFNumberGetValue(CFDictionaryGetValue(battery, CFSTR(kIOPSCurrentCapacityKey)),
                   kCFNumberDoubleType, &current);
           CFNumberGetValue(CFDictionaryGetValue(battery, CFSTR(kIOPSMaxCapacityKey)),
                   kCFNumberDoubleType, &max);
  
           *level = (current * 100.0) / max;
  
           CFRelease(battery);
        }
  
        CFRelease(list);
        CFRelease(power_sources);
     }
  }
  
  