Pointer to Struct with Bitfields

Code

#include <stdio.h>

struct UART_ControlRegister {
    unsigned int baudrate : 4;
    unsigned int tx_enable : 1;
    unsigned int rx_enable : 1;
    unsigned int tx_irq_en : 1;
    unsigned int rx_irq_en : 1;
    unsigned int parity_en : 1;
    unsigned int stop_bits : 1;
    unsigned int reserved : 22;
};

void configure_uart(struct UART_ControlRegister *reg) {
    // Your logic here
    reg -> baudrate = 9;
    reg -> tx_enable = 1;
    reg -> rx_enable = 1;
    reg -> tx_irq_en = 1;
    reg -> rx_irq_en = 0;
    reg -> parity_en = 1;
    reg -> stop_bits = 0;
}

int main() {
    struct UART_ControlRegister reg = {0};

    configure_uart(&reg);

    printf("baudrate = %u\n", reg.baudrate);
    printf("tx_enable = %u\n", reg.tx_enable);
    printf("rx_enable = %u\n", reg.rx_enable);
    printf("tx_irq_en = %u\n", reg.tx_irq_en);
    printf("rx_irq_en = %u\n", reg.rx_irq_en);
    printf("parity_en = %u\n", reg.parity_en);
    printf("stop_bits = %u", reg.stop_bits);

    return 0;
}

Solving Approach

• Define the struct with bitfields.
• Receive a pointer to the struct in a function.
• Use pointer (->) to set fields:
  • baudrate = 9
  • tx_enable = 1
  • rx_enable = 1
  • tx_irq_en = 1
  • rx_irq_en = 0
  • parity_en = 1
  • stop_bits = 0
• Print each field using the struct fields.
• Test by creating a struct instance, passing its pointer to the function.