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2.9 Prefix Codes
2.9.3
Flag Change Suppression Prefix (NCC)
The flag change suppression prefix (NCC) code is set before an instruction to
suppress a flag change accompanying the execution of the instruction.
s Flag Change Suppression Prefix (NCC)
Use the flag change suppression prefix (NCC) to suppress unnecessary flag changes.
Changes in the T, N, Z, V, and C flags can be suppressed.
Be careful when you use this prefix with the instructions listed in
Table 2.9-5 "Instructions
Whose Use Requires Caution When the Flag Change Suppression Prefix (NCC) Is Used ".
For more information on the T, N, Z, V, and C flags, see Section
2.7.4 "Condition Code Register
(PS: CCR)".
Table 2.9-5 Instructions Whose Use Requires Caution When the Flag Change Suppression Prefix (NCC)
Is Used
Instruction type
Instruction
Explanation
String instruction
MOVS
SCEQ
FILS
MOVSW
SCWEQ
FILSW
Do not place the NCC prefix before
the string instruction.
Flag change
instruction
AND
CCR,#imm8
OR CCR,#imm8
The condition code register (CCR)
changes as defined in the instruction
specification whether or not a prefix
is used.
The effect of prefix extends to the
next instruction.
PS return instruction
POPW
PS
The condition code register (CCR)
changes as defined in the instruction
specification whether or not a prefix
is used.
The effect of prefix extends to the
next instruction.
ILM setting
instruction
MOV
ILM,#imm8
The effect of prefix extends to the
next instruction.
Interrupt instruction
Interrupt return
instruction
INT
RETI
#vct8
adder16
INT9
INTP
addr24
The condition code register (CCR)
changes as defined in the instruction
specification whether or not a prefix
is used.
Context switch
instruction
JCTX
@A
The condition code register (CCR)
changes as defined in the instruction
specification whether or not a prefix
is used.