Intel 253666-024US - Manual (Page 329)

Vol. 2A 3-283
INSTRUCTION SET REFERENCE, A-M
ENTER—Make Stack Frame for Procedure Parameters
Operation
NestingLevel ← NestingLevel MOD 32
IF 64-Bit Mode (StackSize = 64)
THEN
Push(RBP);
FrameTemp ← RSP;
ELSE IF StackSize = 32
THEN
Push(EBP);
FrameTemp ← ESP; FI;
ELSE (* StackSize = 16 *)
Push(BP);
FrameTemp ← SP;
FI;
IF NestingLevel
= 0
THEN GOTO CONTINUE;
FI;
IF (NestingLevel > 1)
THEN FOR i ← 1 to (NestingLevel - 1)
DO
IF 64-Bit Mode (StackSize = 64)
THEN
RBP ← RBP - 8;
Push([RBP]); (* Quadword push *)
ELSE IF OperandSize = 32
THEN
IF StackSize = 32
EBP ← EBP - 4;
Push([EBP]); (* Doubleword push *)
ELSE (* StackSize = 16 *)
BP ← BP - 4;
Push([BP]); (* Doubleword push *)
FI;
FI;
ELSE (* OperandSize = 16 *)
IF StackSize = 32
THEN
EBP ← EBP - 2;
Push([EBP]); (* Word push *)
ELSE (* StackSize = 16 *)
BP ← BP - 2;
Push([BP]); (* Word push *)