Construct UART Data Frame with Parity Bit

Code

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

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

uint8_t create_uart_frame(uint8_t data, UART_Control *ctrl) {
    // Your logic here
    
    union {
        struct {
            
            uint8_t data : 7;
            uint8_t parity : 1;
        } bits;
        uint8_t raw;
    } record;

    record.raw = data;
     //count bits
    uint8_t bits_cnt = 0;
    for (int i=0; i<7;i++)
        bits_cnt+=((record.bits.data >> i) & 0x01);

    if (ctrl->parity_enable){ //parity enabled
        //parity type
        if (ctrl->parity_type) {//odd
 
            if (bits_cnt % 2 == 0) record.bits.parity=1;
            else record.bits.parity=0;
        }
        else{ //even
            if (bits_cnt % 2 == 0) record.bits.parity=0;
            else record.bits.parity=1; 
        }
    }       
    else {//no parity
    record.bits.parity=0;
    }   
    return record.raw;
}

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;
}

Solving Approach

 

 

 

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Input

85 1 0

Expected Output

frame = 0x55