signal_processing_vorlage/software/signal_processing/rand.c

#include "system/task_rand.h"
#include "system/hardware_task.h"
#include "system/data_channel.h"
#include "system/float_word.h"
#include <stdio.h>
#include <system.h>

int task_rand_run( void * task ) {

    // Nachfolgende Anweisungen Schreiben 1024 Mal den seed Wert in den FIFO für Rand
	rand_config * config = ( rand_config * ) task;
	float_word seed = {.value = config->seed};

	uint32_t lfsr = seed.word;
    uint32_t bit = 0;                    // Must be 32-bit to allow bit << 31 later in the code

	for( uint32_t i = 0; i < DATA_CHANNEL_DEPTH; i++ ) {
		float_word res;

		uint32_t sign = (lfsr >> 31) & 1;
		uint32_t exponent;
		uint32_t mantisse = lfsr & 0x7FFFFF;

		if((lfsr >> 30) & 1) // MSB exponent
		{
			exponent = 128 + ((lfsr >> 23) & 1); // 128 to 129
		}
		else
		{
			exponent = 124 + ((lfsr >> 23) & 3); // 124 to 127
		}

		uint32_t ieee754 = (sign << 31) | (exponent << 23) | mantisse;
		res.value = ieee754;

		data_channel_write( config->base.sink, ieee754);

		// fibonacci feedback polynomial: x^31 + x^21 + x^1 + 1
		bit = ((lfsr >> 31) ^ (lfsr >> 21) ^ (lfsr >> 1)) & 1;
        lfsr = (lfsr << 1) | bit;
	}

	return 0;
}