Time equation questions

From an earlier thread I have applied some knowledge from Mike, Phil & Jonny Mac.

I am playing around with time equations. I recieve time of day from a RTC object in a string buffer. I was looking at a way of converting that string buffer back into a number and then being able to do some calculations with it like subtracting one time from another to figure the difference and be able to display it.

Here's my playground of code:

CON
        _clkmode = xtal1 + pll16x                                               'Standard clock mode * crystal frequency = 80 MHz
        _xinfreq = 5_000_000

        MS_001   = 80_000_000 / 1_000  

VAR
  long  time, seconds, TimeBuffer1, TimeBuffer2

  byte  TimeString1[10], TimeString2[10]
   
OBJ

  term : "fullduplexserial"  
  
PUB main | hours, minutes, secs, seconds1, seconds2, totalsecs1, totalsecs2, diffseconds

  term.start(31, 30, %0000, 115_200)

  pause(1000)
  
  seconds := 122

  time := time + seconds

  minutes := time / 60
  secs := time // 60

  term.dec(time)
  term.str(string(" Seconds = "))
  term.dec(minutes)
  term.str(string(" Minutes and "))
  term.dec(secs)  
  term.str(string(" Seconds",13, 13))

  TimeString1[0] := "1"                                 ' Assign ASCII string numbers to buffer
  TimeString1[1] := "2"
  TimeString1[2] := ":"
  TimeString1[3] := "0"
  TimeString1[4] := "5"
  TimeString1[5] := ":"
  TimeString1[6] := "3"
  TimeString1[7] := "0"
  TimeString1[8] := 0

  TimeString2[0] := "1"
  TimeString2[1] := "1"
  TimeString2[2] := ":"
  TimeString2[3] := "0"
  TimeString2[4] := "8"
  TimeString2[5] := ":"
  TimeString2[6] := "5"
  TimeString2[7] := "5"
  TimeString2[8] := 0

  term.str(@TimeString1)                                ' Display ASCII strings
  term.tx(32)
  term.str(@TimeString2)
  term.tx(13)

  TimeBuffer1 := (StrToDec(@TimeString1))               ' Convert ASCII number strings to decimal number
  TimeBuffer2 := (StrToDec(@TimeString2)) 
                                                        
  term.dec(StrToDec(@TimeString1))                      ' Display decimal number
  term.tx(32)
  term.dec(StrToDec(@TimeString2))
  term.tx(13)


  term.dec(TimeBuffer1 // 10)                           ' Play wih Modulus function to see what it does
  term.tx(" ")
  term.dec(TimeBuffer1 // 100)
  term.tx(" ") 
  term.dec(TimeBuffer1 // 1000)
  term.tx(" ") 
  term.dec(TimeBuffer1 // 10000)
  term.tx(" ") 
  term.dec(TimeBuffer1 // 100000)
  term.tx(" ") 
  term.dec(TimeBuffer1 // 1000000)
  term.tx(" ") 
  term.dec(TimeBuffer1 // 10000000)
  term.tx(13)

  term.dec(TimeBuffer1 / 10000)                         ' Divide number by 10,000 to get hours
  term.tx(13)

  seconds1 := (TimeBuffer1 // 100)                                              ' Seconds
  seconds1 := seconds1 + ((((TimeBuffer1 // 10000) - seconds1) / 100) * 60)     ' Minutes converted to seconds
  seconds1 := seconds1 + ((TimeBuffer1 / 10000) * 3600)                         ' Hours converted to seconds

  seconds2 := (TimeBuffer2 // 100)                                              ' Seconds
  seconds2 := seconds2 + ((((TimeBuffer2 // 10000) - seconds2) / 100) * 60)     ' Minutes converted to seconds
  seconds2 := seconds2 + ((TimeBuffer2 / 10000) * 3600)                         ' Hours converted to seconds

  term.dec(seconds1)
  term.tx(32)
  term.dec(seconds2)
  term.tx(13)

  diffseconds := seconds1 - seconds2                    ' Figure time difference in seconds
  term.dec(diffseconds)
  term.tx(13)
  
  hours := diffseconds / 3600                           ' Convert seconds difference into Hours, Minutes and Seconds 
  minutes := diffseconds / 60                           
  secs := diffseconds // 60

  term.dec(hours)
  term.str(string(" Hours, "))
  term.dec(minutes)
  term.str(string(" Minutes and "))
  term.dec(secs)  
  term.str(string(" Seconds",13, 13))


PUB StrToDec(stringptr) : value | char, index, multiply

    '' Converts a zero terminated string representation of a decimal number to a value

    value := index := 0
    repeat until ((char := byte[stringptr][index++]) == 0)
       if char => "0" and char =< "9"
          value := value * 10 + (char - "0")
    if byte[stringptr] == "-"
       value := - value
       
pub pause(ms) | t

  t := cnt
  repeat ms
    waitcnt(t += MS_001)

I take 2 different time buffers that were stored as ASCII strings, convert them to decimal number, break them apart (parse?) to get the hour, minutes and seconds. Then convert the hours and minutes to seconds. Then add all the seconds together. I do this for both strings and then find the difference in seconds then go and convert the difference in seconds back into hours, minutes and seconds.

Seems like I took the long way around to get to the answer.

My question- is there a simpler / easier way to take 2 ASCII time strings and find the difference in hours, minute & seconds?

Thanks.
Don