float_conversion.py

# float_conversion.py
import sys
import random
from binary_fractions import Binary

options = '''
Enter an option:
a........ Practice: binary16 floats --> real numbers
b........ [Some issues] Practice: real numbers --> binary16 floats
c........ [Not implemented] Step by Step Practice: real number -> binary16 float
d........ [Not implemented] Step by Step Practice: binary16 float -> real number
e........ Show the values of each bit in a binary fraction
q........ Quit
'''

incorrect_guess = 'Incorrect. Try again or enter \'q\' to quit.'

bit_values = '''
1/2 : 0.5
1/4 : 0.25
1/8 : 0.125
1/16 : 0.0625
1/32 : 0.03125
1/64 : 0.015625
1/128 : 0.0078125
1/256 : 0.00390625
1/512 : 0.001953125
1/1024 : 0.0009765625
'''

def get_bin16_real_pair():
	# Generate a random 16 bits
	bin16 = ''
	for i in range(16):
		bin16 += str(random.randint(0, 1))

	# Determine exponent in decimal
	exp = int(bin16[1:6], 2)

	# Remove exponent bias
	exp -= 15;

	# Convert significand to decimal
	significand = 1.0
	bit = 2
	for digit in bin16[6::]:
		if digit == '1':
			significand += (1 / bit)
		bit *= 2

	real = ''

	if bin16[0] == '1':
		real += '-'

	real += str(significand * (2 ** exp))

	if len(real[real.find('.'):]) > 6:
		real = real[0:real.find('.') + 6]

	return [bin16, real]



def binary16_to_real():
	pair = get_bin16_real_pair()
	
	print('Convert to real up to 5 decimal places: ' + pair[0])
	
	guess = input()

	while guess != pair[1] and guess != 'q':
		print('Incorrect. Guess again or enter q to quit.')
		guess = input()
	
	if guess == pair[1]:
		print("Correct!")
	
	print('The real number was' + pair[1])

	print(options)

def real_to_binary16():
	pair = get_bin16_real_pair()

	while len(pair[1][pair[1].find('.'):]) > 6 or \
	len(pair[1][:pair[1].find('.')]) > 5:
		pair = get_bin16_real_pair()

	print('Convert to a binary16 float:' + pair[1])

	guess = input().replace(' ', '')

	while guess != pair[0] and guess != 'q':
		print('Incorrect. Guess again or enter q to quit.')
		if len(guess) != 16:
			print('Your guess was ' + str(len(guess)) + ' bits long. It should be 16')

		guess = input().replace(' ', '')
	
	if guess == pair[0]:
		print("Correct!")
	
	print('The binary16 float was' + pair[0])

	print(options)

def real_to_binary16_steps():
	pair = get_bin16_real_pair()

	#while len(pair[1][pair[1].find('.'):]) > 6 or \
	#len(pair[1][:pair[1].find('.')]) > 5:
	#	pair = get_bin16_real_pair()

	print('Convert to a binary16 float:' + pair[1])

	sign_bit = pair[0][0]

	print('Step 1: Determine sign bit. 0 if positive, 1 if negative.')
	sign_bit_guess = ''
	while sign_bit_guess != sign_bit:
		if sign_bit_guess == 'q':
			return
		sign_bit_guess = input("Enter the sign bit:")
		print('Try again.')

	print('Okay, we have the sign bit. Our number is now ' + sign_bit + (15 * '□'))

	pure_binary_abs_value = abs(float(pair[1]))

	print('Step 2: Convert the absolute base 10 value to pure binary.')


	fixed_point = str(Binary(pure_binary_abs_value))[2:]

	# If the fixed point value is whole, we need to add '.0'
	if fixed_point.find('.') == -1:
		fixed_point += '.0'

	fixed_point_guess = ''

	while fixed_point_guess != fixed_point:
		if fixed_point_guess == 'q':
			return
		fixed_point_guess = input('Enter ' + str(pure_binary_abs_value) + ' in fixed point binary:')
		print(incorrect_guess)

	print('Correct!')
	print('The fixed point value is ' + fixed_point)

	# Compute Distance between binary point and leftmost 1. 
	leftmost_one_pos = fixed_point.find('1')
	binary_point_pos = fixed_point.find('.')

	one_point_distance = binary_point_pos - leftmost_one_pos

	print('distance to move binary pt: ' + str(one_point_distance))

	print(options)


def main() -> int:
	# Game loop
	print(options)
	c = input()
	while c != 'q':
		
		# Player chose binary16->real
		if c == 'a':
			binary16_to_real()
		elif c == 'b':
			real_to_binary16()
		elif c == 'c':
			real_to_binary16_steps()
		elif c == 'e':
			print(bit_values)

		# Get next choice
		c = input()


if __name__ == '__main__':
	sys.exit(main())