This is the question:
By definition of the IEEE754 standard, 32-bit floating point numbers are represented as follows:
S (1 bit) E (8 bits) M (23 bits) S: Sign bit E: Exponent M: Mantissa
Which of the following is the correct “mask bits” in hexadecimal to be used for extracting only the exponent part of the above format?
Here, “mask bits” means a bit pattern which is logically ANDed withthe 32-bit floating point value.a) 107FFFFF b) 7F800000 c) FF100000 d) FF800000
The given answer is b : 7F800000, but i have no idea why, can anyone give me an explanation, i'm greatly appreciated!
Is that because :
7F800000 = 0111 1111 1000 (8)
While other answers contain more "1" in binary format?
a 32-bit floating point numbers is a sequence of 32 bits. According to the definitions, the bits are arranged as follows
[S][EEEEEEEE][MMMMMMMMMMMMMMMMMMMMMMM]
Thus, the mask we want is: [0][11111111][00000000000000000000000]
Now, we remove the grouping and turn it to hexadecimal...
0111 1111 1000 0000 0000 0000 0000 0000
which translates to (b).