A non-traditional matrix keyboard scanning function

#define scan_key_port P3

uchar key_scan()
{
    uchar sccode,recode;
    uchar key_value;
    scan_key_port=0xf0; /* Send all "0" row scan code, column line input*/
    if((scan_key_port&0xf0)!=0xf0) /* If a key is pressed*/
    {
        delay_1ms(1); /* Delay to de-bounce*/
        if((scan_key_port&0xf0)!=0xf0) /* If a key is pressed*/
        {
            sccode=0xfe; /* Scan the initial value line by line*/
            while((sccode&0x10)!=0)
            {
                scan_key_port=sccode; /* Output row scan code*/
                if((scan_key_port&0xf0)!=0xf0) /* A key is pressed in this line*/
                {
                    recode=(scan_key_port&0xf0)|0x0f;
                    key_value=(~sccode)+(~recode);/* return the signature*/
                 }
                else sccode=(sccode<<1)|0x01; /* shift the row scan one position to the left*/
            }
        }
     } 
    else { //if no key is pressed
     scan_key_port = 0xff;
  return (0);
}
    scan_key_port = 0xff; /*release the key scan port*/
    switch(key_value){ /*display the silk screen corresponding to the key
*/     case 0x11:
     return('0');
    
    case 0x12:
     return('1');
    
    case 0x14:
     return('2');
    
    case 0x21:
     return('3');
    
    case 0x22:
     return('4');
    
    case 0x24:
     return('5');
    
    case 0x41:
     return('6');
    
    case 0x42:
     return('7');
    
    case 0x44:
     return('8');
    
    case 0x81:
     return('9');
    
    case 0x82:
     return('A');
    
    case 0x84:
     return('B');
    
    case 0x18:
     return('C');
    
    case 0x28:
     return('D');
    
    case 0x48:
     return('E');
    
    case 0x88:
     return('F');
    }
}