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Random byte from a Int32

 
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hmmpic



Joined: 09 Mar 2010
Posts: 314
Location: Denmark

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Random byte from a Int32
PostPosted: Sat Mar 02, 2019 1:16 pm     Reply with quote
I have a random serial number from a chip ex: 0x12345678 and need a random byte from this, 0x00 to 0xFF.

The serial is from a chip so not two are the same!

Most simple was to use one of the byte from the 4 byte Int32 but the generated serial can change in any of the byte therefore we cant know which one to use...

Simple, how to get a single random byte from the Int32?
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Sat Mar 02, 2019 1:51 pm     Reply with quote
Use the srand() and rand() functions:
Code:

#include <16F1847.H>
#fuses INTRC_IO, NOWDT
#use delay(clock = 4M)
#use rs232(baud = 9600, UART1, ERRORS)

#define RAND_MAX 255
#include <stdlib.h>

//====================================
void main()
{
int8 result;
int32 seed;

seed = 0x12345678;

srand(seed);

result = rand();

printf("%u  ", result);


while(TRUE);

}
hmmpic



Joined: 09 Mar 2010
Posts: 314
Location: Denmark

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PostPosted: Sat Mar 02, 2019 2:29 pm     Reply with quote
Thanks
Only reason I skipped that was I thought the seed was a int8.
Super I just use that.
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