Prints the value of a binary representation of a binary32 float number

binary2float.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-


# namespace
# {

# void printBinary(const float value)
# {
# 	char s[33];
# 	union {
# 		float f;
# 		unsigned char c[sizeof(float)];
# 	} u;

# 	u.f = value;
# 	for (size_t i = sizeof(float); i-- != 0;) {
# 		for (unsigned j = 8; j-- != 0;) {
# 			s[31 - (i * 8 + j)] = (u.c[i] & (1u << j)) ? '1' : '0';
# 		}
# 	}

# 	s[32] = '\0';
# 	printf("%s", s);
# }

# } // namespace


radix = 2
coefficients = [1 / (radix**i) for i in range(0, 24)]


def sign(s):
    i = int(s, radix)
    if i == 0:    # (-1) ^ 0 =  1
        return 1
    elif i == 1:  # (-1) ^ 1 = -1
        return -1
    raise ValueError


def exp(s):
    i = int(s, radix)
    if 0 <= i <= 255:
        return i - 127
    raise ValueError


def coef(s):
    return sum(
        coefficients[i] for (i, bit) in enumerate(s, start=1)
        if bit == '1'
    )


def b2f(b):
    b = b.replace(' ', '').strip()
    s = sign(b[0])
    e = exp(b[1:9])
    c = coef(b[9:32])
    # print('s={}, e={}, c={}'.format(s, e, c))
    return s * (1 + c) * (radix**e)


def main():
    f = '0 01111100 01000000000000000000000'
    # f = '10000100 00011010 00110111 01100000'
    print(b2f(f))


if __name__ == '__main__':
    main()