HSERIN + interrupt

Hi everyone,
I was wondering if anyone can enlighten me in achieving my application in mind. I want to receive data from pc with in the following format "A123", B"10", "C5"
where A, B and C is the start data letter and after it are numeric values ranging from 1-255. I did a little research, and mostly I found HSERIN command being used ex.(hserin 1000, _WaitTimeOut, [str rbuffer\5\13]). but not really sure how I can incorporate what I have so far.
The following code (from Mr_e) is what I'm using right now, but I need to incorporate a string filtering for incoming data like "A123".

Code:

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Include "modedefs.bas"
DEFINE osc 20            ' We're using a 4 MHz oscillator


' Define ADCIN parameters
Define ADC_BITS    8  ' Set number of bits in result
Define ADC_CLOCK    3  ' Set clock source (3=rc)
Define ADC_SAMPLEUS 50  ' Set sampling time in uS


adval Var Byte          ' Create adval to store result
i        Var Byte      ' For-loop variable
position Var Byte      ' LED position variable
bright1  Var Byte      ' Brightness variable 


'    PORT setting
    '    ============
        '
        TRISA  = 000001    ' Set PORTA to all input
        ADCON1 = 000010  ' Set PORTA analog and right justify result
        TRISB=000000
        TRISD=000000
        TRISC=000000        ' RC.7 => USART RX pin set to input
                                ' all other pin set to output
                                '
        TRISB=0                ' RB<7:0> set to output
       
'    USART setting
    '    =============
        ' Since we will not use HSERIN/HSEROUT, we must
        ' write directly to internal PIC register
        '
        TXSTA=$24              ' enable transmit and SPBRGH=1
        RCSTA=$90              ' Enable USART and continuous receive
        SPBRG=129          ' BAUD RATE = 9600 BAUDS


'    Interrupt definition
    '    ====================
        '
        PIE1.5  =1            ' enable USART receive interrupt
        INTCON.6 =1            ' enable peripheral interrupt
   
    '    Alias definition
    '    ================
        '
        RCIF      var PIR1.5  ' receiver interrupt
        StatusLED var PORTB.2  ' the LED who show a 'running process'
       
    '    Variable definition
    '    ===================
        '
        Delay    var word    '
        DataIn    var byte    ' use to store RCREG content
        Discard  var byte    ' use to erase RCREG register
        cntr      var byte
        cntr = 1
       
    '    Hardware/software initialisation
    '    ================================                                                                                                                                             
        '
        PORTB=0                ' clear PORTB
        PORTC=0
        PORTD=0       
        on interrupt goto USARTInterrupt


   
    PAUSE 500          ' Wait .5 second


loop1:
    ADCIN 0, adval            ' Store ADC value to adval
    Hserout["Data recieve:",adval,13]
    GOTO loop1              ' Do it forever


    END
   
disable interrupt
USARTInterrupt:
    '    Here's the interrupt routine who will make the user
    '    much happy by giving him the feeling to have the
    '    control on the machine when the status of the user
    '    LED will change
    '
    RCSTA=0                    ' Disable serial port AND
                                ' clear possible error (FERR,OERR)
                               
    datain=RCREG                ' Get data
                               
    while RCif                  ' wait untill the RCREG is empty
          discard=RCREG        ' by reading it and store result in a
    wend                        ' don't care variable
                               
    select case datain          ' What to do with that data???
                               
          case "1"            ' User selection = 1
                PortB.0 = 1       
                               
          case "2"          ' User selection =2
                PortB.0 = 0
    '------------------------------1---------------------------------                                                         
                                             
                               
          end select         
    RCSTA=$90                  ' Re-enable the serial PORT AND
    resume                      ' get out of here
enable interrupt

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Thanks in advance,
tacbanon