Hi,

i'm trying to control a system by serial raws, using the "comport" Pd object.

The problem is that my codification of parameters is in converted decimals from 2's complement binary.

for example:

if I had to send the control 132 with two parameters 500 and -500: something like 132(500, -500). It should be done like this:

First parameter 500:

• in hexadecimal = 1F4;
• divide in two 8-bit components, like 1 and F4
• send them in a raw in decimal representation 1 = 1; F4 = 244

Second parameter -500:

• represent as 2's complement = FB00
• divide FB and 00
  send as a raw in decimal 251 and 0

so the message should be like "132 1 244 251 0" for 132(500, -500).

There is any object for Pd to help me with this hexadecimal handling?

It would help me very much, thanks!

You could just skip the hex conversion by using [div] and [mod]. An 8-bit number in hex (or any format) has a decimal range of 256 values. So it's just a matter of dividing by that and getting the remainder.

[500\
|
[trigger f f]
| |
[div 256] [mod 256]
| |
[1\ [244\

I don't actually know what two's compliment is, but I bet you could find a similar solution.

two's complement is a protocol for negative numbers in binary:

for example:

in 8-bits representation;

15 = 00001111

to obtain -15 in one's complement, just have to set the signal bit(most relevant), to high;
(ones complement)(-15) = 10001111

In twos complement, it is quite dferent, after seting the signal bit, we have to negate all the other bits and them sum 1 to the result:

1. 15 = 00001111
2. set the signal bit = 10001111
   3 negate all the other bits = 11110000
   4)sum 1 = 11110001 = -15 = 0xF1

So the algorithm is simple, but in Pd's documentation, I did not found any reference to some important stuf i needed, such as XOR and NEGATE bitwise operator. Is there some other solution for that, or i will have to implement these logical operators with the shifts operators?

C-style bitwise operators can be done using [expr].

Thank you, very very much, [expr] works just perfect!