How do I convert the hex value from a buffer to display in decimal?

Don M · 2012-06-06 12:54

I am receiving 2 bytes of data into a buffer-

             cdinx := 2
             chksum := $03
             repeat
                s := receive.rx_time(10)
                if (s & $1_00)
                   chksum &= $0_FF
                    p := 1 
                   pollack
                   quit
                else
                   p := 0   
                chksum += s
                buffer1[cdinx] := s
                cdinx += 1

And then displaying it using this-

   vmc.CdBeginSesX(@buffer1)

   term.str(string("Credit: "))
   term.hex(buffer3[2], 2)
   term.hex(buffer3[3], 2)

They are stored as hex values and will print that way but I need to see them in decimal form. For example let's say I have 01 2C hex stored in the buffer which is the equivalent of 300 decimal. Using term.hex I get 012C displayed on the terminal.

But if I use term.dec I get 144 which is the 01 converted to 1 and the 2C converted to 44. How do I put the 012C together so it converts to 300?

Thanks.
Don

Edit: changed to solved.

jmg · 2012-06-06 13:11

Don M wrote: »

How do I put the 012C together so it converts to 300?

My calculator says this
0x1*256+0x2C = 300
ie simply multiply the high byte by 256 and add to the lower byte.

Don M · 2012-06-06 14:00

Maybe the question should be- how do I retrieve the 2 bytes together as one word (?) or long (?) and then just use term.dec to display?

Don M · 2012-06-06 14:13

Ok I got it to work like this-

term.str(string("Credit: "))
   credit := (buffer1[2]) * 256
   credit += (buffer1[3])
   term.dec(credit)

Is this the proper way? I defined credit as a long.

Thanks.
Don

Mike G · 2012-06-06 19:31

Don M, here's another way to look at it. This example places the value 1024 ($0400) into memory one byte at a time - $00 followed by $04. The word command is used to return a word aligned data type from memory. Check out byte, word, and long commands in the Propeller manual.

CON
  _clkmode = xtal1 + pll16x     
  _xinfreq = 5_000_000

DAT
  buff  byte  $2[0]

VAR

OBJ
  pst           : "Parallax Serial Terminal"

PUB Main

  pst.Start(115_200)
  pause(500)

  buff[0] := $00
  buff[1] := $04

  pst.dec(word[@buff])
  
  
PRI pause(Duration)  
  waitcnt(((clkfreq / 1_000 * Duration - 3932) #> 381) + cnt)
  return

Mike Green · 2012-06-06 19:48

Note that the above won't work if buff is not word aligned. Much better would be to declare a word or long value and then access the individual bytes to set it up like:

PUB example | temp
   temp.byte[0] := $00   ' least significant byte
   temp.byte[1] := $04   ' most significant byte
   pst.dec(temp.word)   ' display word value in decimal

Duane Degn · 2012-06-06 20:32

Not that this is the best way to do this, but if you do want a byte buffer long aligned you can use the org statement.

DAT
           org
  buff    byte  0[2]

BTW, Mike G, you got your two and zero switched around. I assume you want two bytes of zeros and zero bytes of twos.

Ariba · 2012-06-06 21:29

Don M wrote: »
Ok I got it to work like this-
term.str(string("Credit: "))
   credit := (buffer1[2]) * 256
   credit += (buffer1[3])
   term.dec(credit)
Is this the proper way? I defined credit as a long.

Thanks.
Don

You don't need the parentheses and you can write it on one line:

credit := buffer1[2] * 256 + buffer1[3]

Because a byte has 8 bits you can also shift the high byte by 8 (it's the same as * 256, but faster):

credit := buffer1[2] << 8 + buffer1[3]

Andy

Don M · 2012-06-07 05:53

Ariba wrote: »
You don't need the parentheses and you can write it on one line:
credit := buffer1[2] * 256 + buffer1[3]
Because a byte has 8 bits you can also shift the high byte by 8 (it's the same as * 256, but faster):
credit := buffer1[2] << 8 + buffer1[3]
Andy

Andy- Thanks for those tips!

How do I convert the hex value from a buffer to display in decimal?

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