152 lines
2.9 KiB
C
152 lines
2.9 KiB
C
|
/* Display structure of floating-point numbers */
|
||
|
|
|
||
|
|
#include <stdio.h>
|
||
|
|
#include <stdlib.h>
|
||
|
|
float strtof(const char *nptr, char **endptr);
|
||
|
|
|
||
|
|
#define FLOAT_SIZE 32
|
||
|
|
#define FRAC_SIZE 23
|
||
|
|
#define EXP_SIZE 8
|
||
|
|
#define BIAS ((1<<(EXP_SIZE-1))-1)
|
||
|
|
#define FRAC_MASK ((1<<FRAC_SIZE)-1)
|
||
|
|
#define EXP_MASK ((1<<EXP_SIZE)-1)
|
||
|
|
|
||
|
|
/* Floating point helpers */
|
||
|
|
unsigned f2u(float f)
|
||
|
|
{
|
||
|
|
union {
|
||
|
|
unsigned u;
|
||
|
|
float f;
|
||
|
|
} v;
|
||
|
|
v.u = 0;
|
||
|
|
v.f = f;
|
||
|
|
return v.u;
|
||
|
|
}
|
||
|
|
|
||
|
|
static float u2f(unsigned u)
|
||
|
|
{
|
||
|
|
union {
|
||
|
|
unsigned u;
|
||
|
|
float f;
|
||
|
|
} v;
|
||
|
|
v.u = u;
|
||
|
|
return v.f;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Get exponent */
|
||
|
|
unsigned get_exp(unsigned uf)
|
||
|
|
{
|
||
|
|
return (uf>>FRAC_SIZE) & EXP_MASK;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Get fraction */
|
||
|
|
unsigned get_frac(unsigned uf)
|
||
|
|
{
|
||
|
|
return uf & FRAC_MASK;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Get sign */
|
||
|
|
unsigned get_sign(unsigned uf)
|
||
|
|
{
|
||
|
|
return (uf>>(FLOAT_SIZE-1)) & 0x1;
|
||
|
|
}
|
||
|
|
|
||
|
|
void show_float(unsigned uf)
|
||
|
|
{
|
||
|
|
float f = u2f(uf);
|
||
|
|
unsigned exp = get_exp(uf);
|
||
|
|
unsigned frac = get_frac(uf);
|
||
|
|
unsigned sign = get_sign(uf);
|
||
|
|
|
||
|
|
printf("\nFloating point value %.10g\n", f);
|
||
|
|
printf("Bit Representation 0x%.8x, sign = %x, exponent = 0x%.2x, fraction = 0x%.6x\n",
|
||
|
|
uf, sign, exp, frac);
|
||
|
|
if (exp == EXP_MASK) {
|
||
|
|
if (frac == 0) {
|
||
|
|
printf("%cInfinity\n", sign ? '-' : '+');
|
||
|
|
} else
|
||
|
|
printf("Not-A-Number\n");
|
||
|
|
} else {
|
||
|
|
int denorm = (exp == 0);
|
||
|
|
int uexp = denorm ? 1-BIAS : exp - BIAS;
|
||
|
|
int mantissa = denorm ? frac : frac + (1<<FRAC_SIZE);
|
||
|
|
float fman = (float) mantissa / (float) (1<<FRAC_SIZE);
|
||
|
|
printf("%s. %c%.10f X 2^(%d)\n",
|
||
|
|
denorm ? "Denormalized" : "Normalized",
|
||
|
|
sign ? '-' : '+',
|
||
|
|
fman, uexp);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Extract hex/decimal/or float value from string */
|
||
|
|
static int get_num_val(char *sval, unsigned *valp) {
|
||
|
|
char *endp;
|
||
|
|
/* See if it's an integer or floating point */
|
||
|
|
int ishex = 0;
|
||
|
|
int isfloat = 0;
|
||
|
|
int i;
|
||
|
|
for (i = 0; sval[i]; i++) {
|
||
|
|
switch (sval[i]) {
|
||
|
|
case 'x':
|
||
|
|
case 'X':
|
||
|
|
ishex = 1;
|
||
|
|
break;
|
||
|
|
case 'e':
|
||
|
|
case 'E':
|
||
|
|
if (!ishex)
|
||
|
|
isfloat = 1;
|
||
|
|
break;
|
||
|
|
case '.':
|
||
|
|
isfloat = 1;
|
||
|
|
break;
|
||
|
|
default:
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
if (isfloat) {
|
||
|
|
float fval = strtof(sval, &endp);
|
||
|
|
if (!*endp) {
|
||
|
|
*valp = *(unsigned *) &fval;
|
||
|
|
return 1;
|
||
|
|
}
|
||
|
|
return 0;
|
||
|
|
} else {
|
||
|
|
long long int llval = strtoll(sval, &endp, 0);
|
||
|
|
long long int upperbits = llval >> 31;
|
||
|
|
/* will give -1 for negative, 0 or 1 for positive */
|
||
|
|
if (valp && (upperbits == 0 || upperbits == -1 || upperbits == 1)) {
|
||
|
|
*valp = (unsigned) llval;
|
||
|
|
return 1;
|
||
|
|
}
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
void usage(char *fname) {
|
||
|
|
printf("Usage: %s val1 val2 ...\n", fname);
|
||
|
|
printf("Values may be given as hex patterns or as floating point numbers\n");
|
||
|
|
exit(0);
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
int main(int argc, char *argv[])
|
||
|
|
{
|
||
|
|
int i;
|
||
|
|
unsigned uf;
|
||
|
|
if (argc < 2)
|
||
|
|
usage(argv[0]);
|
||
|
|
for (i = 1; i < argc; i++) {
|
||
|
|
char *sval = argv[i];
|
||
|
|
if (get_num_val(sval, &uf)) {
|
||
|
|
show_float(uf);
|
||
|
|
} else {
|
||
|
|
printf("Invalid 32-bit number: '%s'\n", sval);
|
||
|
|
usage(argv[0]);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
|