I have an Xcode project that include a .c file and .h header file. I am getting a duplicate symbol error and I cannot pinpoint what part of my code is the issue or maybe if it's a configuration issue in my Xcode settings or not.
Here's my .h header file code with my declarations:
#define smc_h
#include <stdint.h>
#include <mach/mach.h>
#include <IOKit/IOKitLib.h>
typedef struct {
uint32_t datasize;
uint32_t datatype;
uint8_t data[8];
} SMCVal_t;
extern io_connect_t conn;
kern_return_t openSMC(void);
kern_return_t closeSMC(void);
kern_return_t readSMC(char *key, SMCVal_t *val);
double convertToFahrenheit(SMCVal_t *val);
#endif /* smc_h */
And here is my .c implementation:
#include "smc.h"
#include <mach/mach.h>
#include <IOKit/IOKitLib.h>
io_connect_t conn;
kern_return_t openSMC(void) {
kern_return_t result;
kern_return_t service;
io_iterator_t iterator;
service = IOServiceGetMatchingServices(kIOMainPortDefault, IOServiceMatching("AppleSMC"), &iterator);
if(service == 0) {
printf("error: could not match dictionary");
return 0;
}
result = IOServiceOpen(service, mach_task_self(), 0, &conn);
IOObjectRelease(service);
return 0;
}
kern_return_t closeSMC(void) {
return IOServiceClose(conn);
}
kern_return_t readSMC(char *key, SMCVal_t *val) {
kern_return_t result;
uint32_t keyCode = *(uint32_t *)key;
SMCVal_t inputStruct;
SMCVal_t outputStruct;
inputStruct.datasize = sizeof(SMCVal_t);
inputStruct.datatype = 'I' << 24; //a left shift operation. turning the I into an int by shifting the ASCII value 24 bits to the left
inputStruct.data[0] = keyCode;
result = IOConnectCallStructMethod(conn, 5, &inputStruct, sizeof(SMCVal_t), &outputStruct, (size_t*)&inputStruct.datasize);
if (result == kIOReturnSuccess) {
if (val -> datasize > 0) {
if (val -> datatype == ('f' << 24 | 'l' << 16 | 't' << 8 )) { //bit shifting to from 32bit operation associated with the ASCII charecters'f', 'l', and 't', sets datatype field.
double temp = *(double *)val -> data;
return temp;
}
}
}
return 0.0;
}
double convertToFahrenheit(SMCVal_t *val) {
if(val -> datatype == ('f' << 24 | 'l' << 16 | 't' << 8 )) { //checking if val->datatype is equal to the result of the bit-shifting operation.
double temp = *(double *)val -> data;
return (temp * 9.0 / 5.0) + 32.0;
}
return 0.0;
}