Instruction
Size*
Function
BIXOR
B
C
¬ [(<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.
(<bit no.> of <EAd>) → C
BLD
B
B
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.
C → (<bit no.> of <EAd>)
BST
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
2
3
Read
Modify
Write
Read one data byte at the specified address
Modify one bit in the data byte
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.
P47:
P46:
Input pin, low
Input pin, high
P45 – P40: Output pins, low
The intended purpose of this BCLR instruction is to switch P40 from output to input.
40
HITACHI [ HITACHI SEMICONDUCTOR ]
