Agnostic type int float greater/smaller number comparison

Agnostic type num comparison.md

Simple example on how to compare for greater/smaller floating points and signed integers with one single procedure.

See: http://kkoral.blogspot.com/2014/09/agnostic-type-int-float-greatersmaller.html

encode_float.c

/* Function for encoding the floating point numbers  */
/* (because decoding is symmetric this func will serve also this purpose) */

int32_t encode_float(float f) {
	int32_t *p;

	p = (int32_t *) &f;

	if (f < 0)
		*p = 0x80000000 | ~*p;

	return *p;
}

main.c

/* Complete test program using a macro instead of the encoding function. */

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <stdint.h>
#include <unistd.h>

#define NTEST (1 << 20)

#define TRANS_FLOAT(f) (f < 0 ? 0x80000000 | ~*(int32_t*)&f : *(int32_t*)&f)

int main (int argc, char *argv[])
{
	int i;
	int32_t int1, int2;
	float float1, float2;
	int rnd = open("/dev/urandom", O_RDONLY);

	for (i = 0; i < NTEST; i++) {
		do
			read(rnd, &float1, sizeof(float));
		while (!(float1 == float1));

		do
			read(rnd, &float2, sizeof(float));
		while (!(float2 == float2));

		int1 = TRANS_FLOAT(float1);
		int2 = TRANS_FLOAT(float2);


		if ((int1 > int2) != (float1 > float2)) {
			printf("FAILURE iteration %d\n", i);
			printf("float couple:\t%E\n\t\t%E\n", float1, float2);
			printf("int couple:\t%d\n\t\t%d\n", int1, int2);
			exit(1);
		}
	}
	close(rnd);

	return 0;
}