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Register – FUJITSU MB91460 SERIES FR60 User Manual

Page 405

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Chapter 28 Bit Search

4.Register

4. Register

4.1 BSD0: 0 Detection Register / BSD1:1 Detection Register / BSDC: Changing position

Detection Data Register

This is a register for setting the bit search detection data.

• BSD0: Address 03F0

H

(Access: Word)

• BSD1: Address 03F4

H

(Access: Word)

• BSDC: Address 03F8

H

(Access: Word)

(For the attributes, refer to “

Meaning of Bit Attribute Symbols (Page No.10)

”.)

• Write data used to detect 0, 1 and changing position in each of the registers BSD0, BSD1 and BSDC.

• The result is stored in the detection result register BSRR.

• During 0 detection, the position where “0” is first detected is stored for data written in the order of

MSB(bit31) to LSB(bit0).

• During 1 detection, the position where “1” is first detected is stored for data written in the order of

MSB(bit31) to LSB(bit0).

• During change position detection, the position where a value different from MSB(bit31) is first detected is

stored for data written in the order of bit30 to LSB(bit0).

• The register BSD0 used for 0 detection and the BSRC register used for changing position detection are

write-only. The value during read operation is indefinite.

• Data saved in the bit search can be read if the register BSR1 used to detect 1 is read.

Previous detection result can be restored by re-writing previously read data in the BSR1 used for detecting
1. This applies to the processes for the 0 detection and the changing position detection.This function can be
used to restore a specific state when using a bit search in processing such as interrupt handler.

31

0

bit

BSD0

Indefinite

Initial value

W

Attribute

31

0

bit

BSD1

Indefinite

Initial value

R,W

Attribute

31

0

bit

BSDC

Indefinite

Initial value

W

Attribute