/* PROG: floating
LANG: C
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <math.h>
#define ABSOLUTE_WIDTH 31
#define MANTISSA_WIDTH 23
#define EXPONENT_WIDTH 8
#define EXPONENT_MASK 0xffu
#define MANTISSA_MASK 0x007fffffu
#define EXPONENT_BIAS 127
union float_bits {
float f;
uint32_t bits;
};
void print_float( FILE *output, float f ) {
union float_bits t; t.f = f;
uint32_t sign_bit = ( t.bits >> ABSOLUTE_WIDTH );
uint32_t exponent = ( t.bits >> MANTISSA_WIDTH ) & EXPONENT_MASK;
uint32_t mantissa = ( t.bits & MANTISSA_MASK );
if( sign_bit != 0 ) {
fprintf( output, "-" );
}
if( exponent > 2 * EXPONENT_BIAS ) {
fprintf( output, "Inf\n" ); /* Infinity */
return;
} else if( exponent == 0 ) {
fprintf( output, "0." ); /* Zero or Denormal */
exponent = ( mantissa != 0 ) ? exponent + 1 : exponent;
} else {
fprintf( output, "1." ); /* Usual */
}
for( int k = MANTISSA_WIDTH - 1; k >= 0; --k ) {
fprintf( output, "%d", ( mantissa >> k ) & 1 );
}
if( exponent != 0 || mantissa != 0 ) {
fprintf( output, " * 2^%d\n", (int) ( exponent - EXPONENT_BIAS ) );
}
}
int main() {
FILE *input = fopen( "floating.in", "r" ),
*output = fopen( "floating.out", "w" );
size_t N; float f;
fscanf( input, "%zu", &N );
for( size_t i = 0; i < N; ++i ) {
fscanf( input, "%f", &f );
print_float( output, f );
}
fclose( input );
fclose( output );
return 0;
}
Below is the output using the test data:
floating:
1: OK [0.004 seconds] OK!
2: OK [0.004 seconds] OK!
3: OK [0.004 seconds] OK!
4: OK [0.004 seconds] OK!
5: OK [0.005 seconds] OK!
6: OK [0.004 seconds] OK!
7: OK [0.004 seconds] OK!