U. Glaeser

FIGURE 9.14 Nonrestoring division.
FIGURE 9.15 Example of nonrestoring division.
Binary SRT Divider
The binary SRT division process is similar to nonrestoring division, but the set of allowable quotient
digits is increased to {1, 0, 1}
and the divisor is restricted to .5 ≤ D < 1. The digit selection and resulting
partial remainder are given for the kth iteration by the following relations:
© 2002 by CRC Press LLC
4. q n-k-1 = -1
P k+1 = 2P k + D
P0 = N = 5
8
D = 7
8
n = 4
LT
1. P 0 = N
k = -1
2. k = k + 1
3.
P k : 0
6.
K : n-1
GE
Q = N/D
GE
LT
5. q n-k-1 = 1
P k+1 = 2P k − D
k = 0, Since P0 > 0, then q3 = 1 and P1 = 2P0 − D = 3
8
k = 1, Since P1 > 0, then q2 = 1 and P2 = 2P1 − D = −1
8
_
k = 2, Since P0 < 0, then q1 = 1 and P3 = 2P2 + D = 5
8
k = 3, Since P0 > 0, then q0 = 1 and P4 = 2P3 − D = 3
8
_
Q = 0 .1 1 1 1 (SIGNED DIGIT FORM)
Q = 0 .1 0 1 1 (BINARY)
If Pk ≥ .5, qn−k−1 = 1 and Pk+1 = 2Pk − D (9.28)
If −.5 < Pk < .5, qn−k−1 = 0 and Pk+1 = 2Pk (9.29)
If Pk ≥ .5, qn−k−1 = 1
and Pk+1 = 2Pk + D (9.30)