FUJITSU MB91F109 FR30 - Manual (Page 320)

296
CHAPTER 13 BIT SEARCH MODULE
■ Change-Point Detection
The module scans the data written to the change-point detection data register from bit 30 to LSB
while comparing each bit with the MSB value and returns the position where the value different
from the MSB was first detected.
The detection result can be obtained by reading the detection result register.
The relationships between the detected positions and the values to be returned are summarized in
Table 13.3-1.
If no change-point is detected, 32 is returned.
In change-point detection mode, 0 is not returned as the detection result.
[Execution example]
Write data Read value (decimal)
00100000 00000000 00000000 00000000
B
(20000000
H
) ==> 2
00000001 00100011 01000101 01100111
B
(01234567
H
) ==> 7
00000000 00000011 11111111 11111111
B
(0003FFFF
H
) ==> 14
00000000 00000000 00000000 00000001
B
(00000001
H
) ==> 31
00000000 00000000 00000000 00000000
B
(00000000
H
) ==> 32
11111111 11111111 11110000 00000000
B
(FFFFF000
H
) ==> 20
11111000 01001001 11100000 10101010
B
(F849E0AA
H
) ==> 5
10000000 00000010 10101010 10101010
B
(8002AAAA
H
) ==> 1
11111111 11111111 11111111 11111111
B
(FFFFFFFF
H
) ==> 32
Table 13.3-1 Bit Positions and Returned Values (Decimal)
Detected
bit
position
Returned
value
Detected
bit
position
Returned
value
Detected
bit
position
Returned
value
Detected
bit
position
Returned
value
31 0 23 8 15 16 7 24
30 1 22 9 14 17 6 25
29 2 21 10 13 18 5 26
28 3 20 11 12 19 4 27
27 4 19 12 11 20 3 28
26 5 18 13 10 21 2 29
25 6 17 14 9 22 1 30
24 7 16 15 8 23 0 31
Not
detected
32