lab16-ex2.c

#include <stdio.h>
#include <stdlib.h>

#define makefloat(s,e,f) ((s & 1)<<31 | (((e) & 0xff) << 23) | ((f) & 0x7fffff))
#define getsig(x) ((x)>>31 & 1)
#define getexp(x) ((x)>>23 & 0xff)
#define getfrac(x) ((x) & 0x7fffff)

typedef union {
 float f;
 unsigned int i;
} U;

//ex1
float float2(float f){
	U u;
	u.f = f;
	u.i =  makefloat(getsig(u.i),getexp(u.i)+1,getfrac(u.i));
	return u.f;
}

//ex2
float int2float(int i){
	if(i == 0) return 0.0;

	//descobrir exponencial
	int e = 0;

	i = (i < 0) ? -i : i;
	unsigned int temp =i;

	while(temp != 1){
		//printf("bit: %d\n", temp & 1);
		temp = temp >> 1;
		e++;
	}
	
	int f = i;
	//fazer a mascara
	int mask = 0;
 	for(int j = 0; j < e ;j++){
 		mask = mask << 1;
 		mask = mask | 1;
 		//printf("bit: %d (%d)\n", mask & 1,j );
 	}//printf("\n\n");

 	f = f & mask;
 	f = f << (23-e);

 	printf("%x %x\n", f, mask);

 	//exp
 	int exp = e + 127;

 	//signal
 	int signal = (i < 0);

 	U u;

 	u.i = makefloat(signal, exp, f);


 	//imprimir
 	/*
	for(int j = 0; j < sizeof(int)*8; j++){
		if(j==1 || j==9) printf("------\n");
 		printf("bit(%d): %d \n",j , u.i & 1);
 		u.i <<= 1;
	}*/
 	return u.f;
	
}
int main(){

	//printf("%f\n",float2(5.0));

	printf("\n%.1f\n",int2float(-1521));
	return 0;
}