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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 FFFFFFFFH), ‘32’ is returned as detection result.
Execution example
Write data Read value (Decimal notation)
11111111111111111111000000000000B (FFFFF000H)Æ 20
11111000010010011110000010101010B (F849E0AAH 5
10000000000000101010101010101010B (8002AAAAH 1
11111111111111111111111111111111B (FFFFFFFFH)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 00000000H), value of ‘32’ is returned as detection result.
Execution example
Write data Read value (Decimal notation)
00100000000000000000000000000000B (20000000H 2
00000001001000110100010101100111B (01234567H 7
00000000000000111111111111111111B (0003FFFFH)Æ 14
00000000000000000000000000000001B (00000001H)Æ 31
00000000000000000000000000000000B (00000000H)Æ 32

11111111111 111 1 1 2

0123456 789 A B CDEF0123 456789AB CDEF 0

1111111 111 000 000 0 000000000 0 00 00 0

>>>>>>>>>>0

AH(10 Decimal)
Data
Bit position from MSB
Scan
Detection result

1111111111 111 11 1 2

0123456789 AB CDEF012 3456789AB CDEF 0

0000000000 000 00 0 001111111 111 1 1 11

>>>>>>>>>>>>>>>>>>1

12H(18Decimal)

Data

Bit position from MSB

Scan

Detection result