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Trying to fprint an int16 with 18 characters

 
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cap110874



Joined: 31 Aug 2011
Posts: 1

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Trying to fprint an int16 with 18 characters
PostPosted: Wed Aug 31, 2011 2:42 pm     Reply with quote
Hi Folks - Please bear with me if this sounds a bit stupid -

I am trying to print an int16 with 18 characters.
ie:
int16 PT_IR_pulse_pattern_up = 0b1110100100010110;

I want it to look exactly the same when it fprints to my rs232 terminal but I have tried nearly every combination of %x, %ld ect ect ect and it always comes out different.
This is what i am currently trying:
fprintf(COM_A, "%lx \r\n", PT_IR_pulse_pattern_up);
and in the RS232 terminal it is showing as:
e916

ANY wise words of advice as to where I am going wrong would be greatly appreciated
newguy



Joined: 24 Jun 2004
Posts: 1907

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PostPosted: Wed Aug 31, 2011 2:52 pm     Reply with quote
Code:
signed int8 i;
printf(COM_A, "0b");
for (i = 15; i >= 0; i--) {
   if (bit_test(PT_IR_pulse_pattern_up, i)) {
      printf(COM_A, "1");
   }
   else {
      printf(COM_A, "0");
   }
}
printf(COM_A, " \r\n");


Edit: Thanks TTelmah, bonehead mistake fixed.

Last edited by newguy on Thu Sep 01, 2011 7:26 am; edited 1 time in total
Ttelmah



Joined: 11 Mar 2010
Posts: 19504

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PostPosted: Thu Sep 01, 2011 2:46 am     Reply with quote
Ongoing to this:
1) The key point is that the standard printf function does not provide a '%b' output, which is why you couldn't find a way of doing it directly. It is a rare output now, with hex being much more common, because of it's bulk.
2) Newguy's code shows a simple but quite efficient way of doing it, but as written, the 'wrong way round' - counter needs to go from 15 to 0, not 0 to 15.
3) A search online, will find dozens of other routes, varying in speed, and code size.
As an alternative, the internal function itoa (part of stdlib.h), can canvert a value to it's binary string representation directly.
Another 'natty' route, is a simple lookup table, based upon hex:
Code:

char hex_bin[16][5] = {"0000","0001","0010","0011","0100","0101","0110","0111", \
"1000","1001","1010","1011","1100","1101","1110","1111"};

void ophex_bin(int8 digit) {
   if (digit>'9') {
      if (digit>'F') digit-=0x20;
      digit-=55;
   }
   else digit-='0';
   fprintf(COM_A,"%s",&hex_bin[digit][0]);
}

////........

   int16 PT_IR_pulse_pattern_up = 0b1110100100010110;

   fprintf(COM_A,"0b"); 
   printf(ophex_bin,"%04lx",PT_IR_pulse_pattern_up);
   fprintf(COM_A,"\n\r");

Which converts the individual hex digits, to four character text representations (adds the '0b' text as well).

There are about as many solutions to this, as days in a year!....

Best Wishes
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