Flag Change Suppression Prefix (Ncc) - Fujitsu MB90460 Series Hardware Manual

3.9.3

Flag Change Suppression Prefix (NCC)

The flag change suppression prefix (NCC) code is placed before an instruction to
suppress a flag change accompanying the execution of the instruction.
■ Flag Change Suppression Prefix (NCC)
The flag change suppression prefix (NCC) is used to suppress unnecessary flag changes. If a flag change
suppression prefix code is placed before an instruction, a flag change accompanying the execution of the
instruction is suppressed. Changes of the T, N, Z, V and C flags are suppressed.
Note that caution is required when this prefix is used with the instructions listed in Table 3.9-5.
Table 3.9-5 Instructions whose use requires Caution when the Flag Change Suppression Prefix (NCC) is
used
Instruction type
MOVS
String
SCEQ
instruction
FILS
Flag change
AND CCR, #imm8 OR CCR, #imm8
instruction
PS return
POPW
instruction
ILM setting
MOV
instruction
Interrupt instruction INT
Interrupt return INT
instruction RETI
Context switch
JCTX@A
instruction
Instruction
MOVSW
SCWEQ
FILSW
PS
ILM, #imm8
#vct8 INT9
adder16 INTP addr24
Explanation
Do not place the NCC prefix before the string instruction.
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.
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.
The effect of prefix extends to the next instruction.
The condition code register (CCR) changes as defined in
the instruction specification whether or not a prefix is used.
The condition code register (CCR) changes as defined in
the instruction specification whether or not a prefix is used.
CHAPTER 3 CPU
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