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5 INSTRUCTION SET
5.12 Bit Manipulation Instructions
The following four instructions are provided for manipulating the data in memory bitwise or one bit at a time.
These instructions allow the display memory or I/O map control bits to be altered directly.
btst
[%rb],imm3
bclr
[%rb],imm3
bset
[%rb],imm3
bnot
[%rb],imm3
Bit manipulation is performed on the memory address specified by the rb (general-purpose) register. imm3 specifies
a bit number (bits 0–7) in the byte data stored in that address location.
Although the content of memory data altered by these instructions (except btst) is only the specified bit, the
specified address is rewritten because memory is accessed bytewise. Therefore, if the addresses to be manipulated
have any I/O control bits mapped whose function is enabled by a bit write operation, use of these instructions
requires caution.
36
Set the Z flag if a specified bit = 0
Clear a specified bit to 0
Set a specified bit to 1
Invert a specified bit (1 ↔ 0)
EPSON
S1C33 FAMILY C33 PE CORE MANUAL
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