splitting a binary string

[Kieran Snow]

Hi Folks,
have a fairly basic knowledge of C. I need to take a binary string:
0001000110
cut off the last 4 bits i.e. 0110
store it as X1 and compare it to a previously stored value of X2, if X1 is greater than X2 then store X1 into X2.
any ideas,
Thanks kieran.
___________________________
This message was ported from CCS's old forum
Original Post ID: 13361

[neil]

Hi Kieran, I think the easiest way would be to do this:
(assuming 'X1' is the four LSBs)

o Take the string 00 0100 0110
o Apply an 'AND' mask to it...
0000 0100 0110
AND 0000 0000 1111
= 0000 0000 0110
o Code: X1 = string & 0x006;

OR... Assuming you want to *ignore* the four LSBs...

o Take the string and shift it four places to the RIGHT
eg. X1 = string >>4;

This will push the four LSBs off the end, moving the data you want to the LSB position. The MSB end of the word will have '0' shifted in, so the word will become '0000 0000 0100'

I hope this explains what you were asking!
Neil.


:=Hi Folks,
:=have a fairly basic knowledge of C. I need to take a binary string:
:=0001000110
:=cut off the last 4 bits i.e. 0110
:=store it as X1 and compare it to a previously stored value of X2, if X1 is greater than X2 then store X1 into X2.
:=any ideas,
:=Thanks kieran.
___________________________
This message was ported from CCS's old forum
Original Post ID: 13362

[PCM programmer]

:=Hi Folks,
:=have a fairly basic knowledge of C. I need to take a binary string:
:=0001000110
:=cut off the last 4 bits i.e. 0110
:=store it as X1 and compare it to a previously stored value of X2, if X1 is greater than X2 then store X1 into X2.
----------------------------------------------------

You've stated the problem very well. That's 90\% of the
solution, right there. I think the knowledge you're missing
is how to mask off some bits. But that's easy. Use the
bitwise AND operator. Then just take your words, and translate
them into code.

<PRE>
main()
{
char c;
char x1;
char x2;
<BR>
// Get a value into c, somehow.
<BR>
<BR>
// Save lower 4 bits of c into x1. (Clear the upper 4 bits).
x1 = c & 0x0f;
<BR>
// Compare x1 to x2. If x1 is > x2, then store x1 into x2.
if(x1 > x2)
x2 = x1;
<BR>
while(1);
}
</PRE>
___________________________
This message was ported from CCS's old forum
Original Post ID: 13380