24531904_j

IRET/IRETD—Interrupt Return ( 続き )
操作
IF(Itanium System Environment)
THEN IA-32_Intercept(Inst,IRET);
IF PE = 0
THEN
GOTO REAL-ADDRESS-MODE:;
ELSE
GOTO PROTECTED-MODE;
FI;
REAL-ADDRESS-MODE;
IF OperandSize = 32
THEN
IF top 12 bytes of stack not within stack limits THEN #SS; FI;
IF instruction pointer not within code segment limits THEN #GP(0); FI;
EIP ← Pop();
CS ← Pop(); (* 32-bit pop, high-order 16-bits discarded *)
tempEFLAGS ← Pop();
EFLAGS ← (tempEFLAGS AND 257FD5H) OR (EFLAGS AND 1A0000H);
ELSE (* OperandSize = 16 *)
IF top 6 bytes of stack are not within stack limits THEN #SS; FI;
IF instruction pointer not within code segment limits THEN #GP(0); FI;
EIP ← Pop();
EIP ← EIP AND 0000FFFFH;
CS ← Pop(); (* 16-bit pop *)
EFLAGS[15:0] ← Pop();
FI;
END;
PROTECTED-MODE:
IF VM = 1 (* Virtual-8086 mode: PE=1, VM=1 *)
THEN
GOTO RETURN-FROM-VIRTUAL-8086-MODE; (* PE=1, VM=1 *)
FI;
IF NT = 1
THEN
GOTO TASK-RETURN;( *PE=1, VM=0, NT=1 *)
FI;
IF OperandSize=32
THEN
IF top 12 bytes of stack not within stack limits
THEN #SS(0)
FI;
tempEIP ← Pop();
tempCS ← Pop();
tempEFLAGS ← Pop();
ELSE (* OperandSize = 16 *)
IF top 6 bytes of stack are not within stack limits
THEN #SS(0);
FI;
tempEIP ← Pop();
第 3 巻 : IA-32 基本命令リファレンス 3:601