expanded_binary32.c

#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>

static const uint32_t SIGN_MASK = 0x80000000;
static const uint32_t EXP_MASK  = 0x7f800000;
static const uint32_t FRA_MASK  = 0x007fffff;

int main(int argc, char * argv[]) {
  if (argc < 2) {
    fprintf(stderr, "Please provide a float to parse.\n");
    return -1;
  }

  float source;

  sscanf(argv[1], "%f", &source);

  uint32_t * y = (uint32_t*)&source;

  const bool sign = (*y & SIGN_MASK) >> 31;
  const uint8_t exp = (*y & EXP_MASK) >> 23;
  const uint32_t fra = (*y & FRA_MASK);

  printf("%.45f\n", source);
  printf("%01d %03d %07d\n", sign, exp, fra);
  printf("(-1)^%d * 2^(%d-127) * (1 + (%d / 2^23))\n", sign, exp, fra);

  return 0;
}

expanded_binary64.c

#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>

static const uint64_t SIGN_MASK = 0x8000000000000000;
static const uint64_t EXP_MASK  = 0x7ff0000000000000;
static const uint64_t FRA_MASK  = 0x000fffffffffffff;

int main(int argc, char * argv[]) {
  if (argc < 2) {
    fprintf(stderr, "Please provide a float to parse.\n");
    return -1;
  }

  double source;

  sscanf(argv[1], "%lf", &source);

  uint64_t * y = (uint64_t*)&source;

  const bool sign = (*y & SIGN_MASK) >> 63;
  const uint16_t exp = (*y & EXP_MASK) >> 52;
  const uint64_t fra = (*y & FRA_MASK);

  printf("%.45f\n", source);
  printf("%01d %04d %016lld\n", sign, exp, fra);
  printf("(-1)^%d * 2^(%d-127) * (1 + (%lld / 2^52))\n", sign, exp, fra);

  return 0;
}