Hardware manual

Rev. 3.0, 09/98, page 36 of 361

Table 2.8 Bit-Manipulation Instructions (cont)

Instruction Size

Function

BIXOR BC ⊕ ¬ [(<bit-No.> of <EAd>)] → C

XORs the C flag with the inverse of a specified bit in a general register or

memory.

The bit number is specified by 3-bit immediate data.

BLD B (<bit-No.> of <EAd>) → C

Copies a specified bit in a general register or memory to the C flag.

BILD ¬ (<bit-No.> of <EAd>) → C

Copies the inverse of a specified bit in a general register or memory to the

C flag.

The bit number is specified by 3-bit immediate data.

BST BC → (<bit-No.> of <EAd>)

Copies the C flag to a specified bit in a general register or memory.

BIST ¬ C → (<bit-No.> of <EAd>)

Copies the inverse of the C flag to a specified bit in a general register or

memory.

The bit number is specified by 3-bit immediate data.

Note: Size: operand size

B: Byte

Notes on Bit Manipulation Instructions: BSET, BCLR, BNOT, BST, and BIST are read-

modify-write instructions. They read a byte of data, modify one bit in the byte, then write the byte

back. Care is required when these instructions are applied to registers with write-only bits and to

the I/O port registers.

Step Description

1 Read Read one data byte at the specified address

2 Modify Modify one bit in the data byte

3 Write Write the modified data byte back to the specified address

Example 1: BCLR is executed to clear bit 0 in the port 4 data direction register (P4DDR) under

the following conditions.

: Input pin, Low

: Input pin, High

− P4

: Output pins, Low

The intended purpose of this BCLR instruction is to switch P4

from output to input.