In C programming, the placement of the asterisk (*) is critical for determining pointer semantics. When the asterisk appears inside parentheses with a variable, it declares a pointer.

Pointer Declarations

• char *argp[] - Array of pointers to characters
• void (*func_ptr)(int) - Pointer to a function taking an integer parameter
• int *func_sum(int n) - Function returning a pointer to an integer

String Comparison with Pointers

The strcmp function accepts two pointer arguments for string comparison:

if (strcmp(ptr1, ptr2) == 0)
if (strcmp(argp[1], "fpga") == 0)

Structure Pointer Access Operations

Different operations on structure pointers yield different results:

• *pConfig->workThread - Dereferences the pointer pConfig and accesses the workThread member value
• &pConfig->workThread - Obtains the memory address of the workThread member within the structure pointed to by pConfig

The arrow operator (->) has higher precedence than the address-of operator (&).

Structure Member Access Examples

typedef struct {
    uint32_t flipx;
    uint32_t flipy;
} FlipConfig;

FlipConfig flipSettings[MAX_SENSOR_COUNT];

SystemConfig* configPtr = getSystemConfig();
ThreadInfo* threadParam = &configPtr->workerThread;
ThreadParams* params = configPtr->workerThread.privateData;

OSA_mutexLock(threadParam->workLock);
params->isWorking = false;
OSA_mutexUnlock(threadParam->workLock);

Complex Structure Definitions

typedef struct {
    DRV_AmbHandle driverHandle;
    VBP_Config inputConfig;
    DEBUG_CONFIG debugSettings;
    uint8_t sensorCount;
    SEN_CONFIG sensorConfig[MAX_SENSOR_COUNT];
    uint16_t bayerPattern[MAX_SENSOR_COUNT];
    MODEL_CONFIG* modelConfig[MAX_SENSOR_COUNT];
    VIN_CONFIG vinConfig;
    // Various thread information structures
    THREAD_INFO workerThread;
    THREAD_INFO watchdogThread;
    // Additional configuration arrays
    struct vindev_video_info videoInfo[MAX_SENSOR_COUNT];
    struct iav_chan_cfg channelConfig[MAX_CHANNELS];
} SystemConfig;

SystemConfig* getSystemConfig() {
    return globalConfig;
}

Structure Pointer Arrays

typedef struct {
    IspCaliParam* ispCalibration;
    gainCalcFunc gainFunction;
    JpegEncodeInitData jpegInit;
    senInit sensorInitUser;
    setSenBlackFunc blackFunc;
    setAdcOffsetFunc adcOffsetFunc;
    UniqueConfig* uniqueConfig;
    SensorSpecCONFIG* sensorSpec;
} ModelConfig;

ModelConfig* modelConfigArray[MAX_SENSOR_COUNT];

This demonstrates an array of pointers to ModelConfig structures.