X =
00
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
Y =
00
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
X ↔ Y
Ext-GCD(5, 12) :
i
GCD
Bezout
AOdd :
AEven :
A
↔
B
ax
ay
bx
by
|A-B|
A↔B
Sx
Sy
ax ←
Sx' ay ←
Sy' A ←
A/2 ax ←
ax + Y ay ←
ay + X ax ←
ax/2 ay ←
ay/2
0
5
12
1
0
0
1
1
12
↔
5
0
1
1
0
7
6
12
6
6
3
2
6
↔
5
6
3
1
0
1
3
18
8
9
4
3
3
↔
5
9
4
1
0
2
1
10
4
10
4
1
Even
Even
5
2
4
1
3
5
2
9
4
2
1
14
6
2
1
1
14
6
7
3
5
1
↔
1
7
3
5
2
0
6
1
↔
1
7
3
5
2
0
7
1
1
5
2
7
3
0
(5)(5) - (2)(12) = 1