76. Construct UART Data Frame with Parity Bit

#include <stdio.h>
#include <stdint.h>

typedef struct {
    uint8_t parity_enable : 1;
    uint8_t parity_type   : 1;
    uint8_t reserved      : 6;
} UART_Control;

int count_set_bits(uint8_t data){
    int count = 0;
    while(data != 0){
        count += (data & 0x01);
        data >>= 1;
    }
    return count;
}

uint8_t create_uart_frame(uint8_t data, UART_Control *ctrl) {
    if(!(ctrl -> parity_enable)){
        return data;
    }
    else{
        uint8_t parity = 0;
        int count = count_set_bits(data);
        if(ctrl -> parity_type == 0){
            if(count % 2 != 0) parity = 0x01; 
        }
        else{
            if(count % 2 == 0) parity = 0x01;
        }
        return (parity << 7) | data;
    }
    
}

int main() {
    uint8_t data;
    scanf("%hhu", &data);  // 7-bit input

    uint8_t parity_enable, parity_type;
    scanf("%hhu %hhu", &parity_enable, &parity_type);

    UART_Control ctrl;
    ctrl.parity_enable = parity_enable;
    ctrl.parity_type = parity_type;

    uint8_t frame = create_uart_frame(data, &ctrl);
    printf("frame = 0x%02X", frame);

    return 0;
}