Intel 253666-024US - Manual (Page 716)

3-670 Vol. 2A MOVS/MOVSB/MOVSW/MOVSD/MOVSQ—Move Data from String to String
INSTRUCTION SET REFERENCE, A-M
(E)SI ← (E)SI – 1;
(E)DI ← (E)DI – 1;
FI;
ELSE IF (Word move)
THEN IF DF = 0
(E)SI ← (E)SI + 2;
(E)DI ← (E)DI + 2;
FI;
ELSE
(E)SI ← (E)SI – 2;
(E)DI ← (E)DI – 2;
FI;
ELSE IF (Doubleword move)
THEN IF DF = 0
(E)SI ← (E)SI + 4;
(E)DI ← (E)DI + 4;
FI;
ELSE
(E)SI ← (E)SI – 4;
(E)DI ← (E)DI – 4;
FI;
FI;
64-bit Mode:
IF (Byte move)
THEN IF DF = 0
THEN
(R|E)SI ← (R|E)SI + 1;
(R|E)DI ← (R|E)DI + 1;
ELSE
(R|E)SI ← (R|E)SI – 1;
(R|E)DI ← (R|E)DI – 1;
FI;
ELSE IF (Word move)
THEN IF DF = 0
(R|E)SI ← (R|E)SI + 2;
(R|E)DI ← (R|E)DI + 2;
FI;
ELSE
(R|E)SI ← (R|E)SI – 2;
(R|E)DI ← (R|E)DI – 2;
FI;
ELSE IF (Doubleword move)
THEN IF DF = 0