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Rotate 2 byte

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pilar

Joined: 30 Jan 2008
Posts: 197

Rotate 2 byte

Posted: Thu Jun 09, 2011 3:33 pm

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Hi someone can tell me how I can rotate 2 bytes?

Code:

Example: I hace 0xFD45 I need to have 0x45FD

PCM programmer

Joined: 06 Sep 2003
Posts: 21708

Posted: Thu Jun 09, 2011 4:20 pm

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You can use a swap_bytes() macro. It displays this result:

Quote:

initial value = 1234

result = 3412

Here's the test program:

Code:

#include <16F877.H>
#fuses XT, NOWDT, BROWNOUT, PUT, NOLVP
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS)

#define swap_bytes(x) make16(x, x >> 8)

//==========================================
void main()
{
int16 result;
int16 value;

value = 0x1234;
printf("initial value = %lx \n\r", value);

result = swap_bytes(value);
printf("result = %lx \n\r", result);

while(1);
}

FvM

Joined: 27 Aug 2008
Posts: 2337
Location: Germany

Posted: Thu Jun 09, 2011 4:33 pm

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A byte swap can be effectively performed with built-in functions

Code:

ival16 = make16(make8(ival16,0),make8(ival16,1));

pilar

Joined: 30 Jan 2008
Posts: 197


Posted: Thu Jun 09, 2011 5:07 pm

Thank you...

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