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Chapter 28 Bit Search
5.Operation
5. Operation
5.1 Zero detection
(1) Bit position from MSB
(2) Written data (Starts to search once data is written.)
(3) Detects “0” by scanning from MSB.
(4) Detected bit position
(5) Detection result
If ‘0’ does not exist (That is, numeric value is FFFFFFFF
H
), ‘32’ is returned as detection result.
• Execution example
Write data Read value (Decimal notation)
11111111111111111111000000000000
B
(FFFFF000
H
)Æ 20
11111000010010011110000010101010
B
(F849E0AA
H
)Æ 5
10000000000000101010101010101010
B
(8002AAAA
H
)Æ 1
11111111111111111111111111111111
B
(FFFFFFFF
H
)Æ 32
5.2 One Detection
(1) Bit position from MSB
(2) Written data (Detection operation starts once data is written.)
(3) Detect “1” scan starting with the MSB.
(4) Detected bit position
(5) Detection result
If ‘1’ does not exist (That is, if numeric value is 00000000
H
), value of ‘32’ is returned as detection result.
• Execution example
Write data Read value (Decimal notation)
00100000000000000000000000000000
B
(20000000
H
)Æ 2
00000001001000110100010101100111
B
(01234567
H
)Æ 7
00000000000000111111111111111111
B
(0003FFFF
H
)Æ 14
00000000000000000000000000000001
B
(00000001
H
)Æ 31
00000000000000000000000000000000
B
(00000000
H
)Æ 32
11111111111 111 11 2
0123456 789 ABCDEF0123456789ABCDEF 0
1111111 111 000 000 0000000000 000 000
>>>>>>>>>>
0
A
H
(10
Decimal
)
Data
Bit position from MSB
Scan
Detection result
1111111111 111 111 2
0123456789 ABCDEF0123456789ABCDEF 0
0000000000 000 000 001111111111 11 11
>>>>>>>>>>>>>>>>>>1
12
H
(18
Decimal
)
Data
Bit position from MSB
Scan
Detection result