Datasheet

15 0
7 0
C
Byte
Word
0
www.ti.com Instruction Set
3.4.6.38 RLA
*RLA[.W] Rotate left arithmetically
*RLA.B Rotate left arithmetically
Syntax RLA dst or RLA.W dst
RLA.B dst
Operation C <- MSB <- MSB-1 .... LSB+1 <- LSB <- 0
Emulation ADD dst,dst
ADD.B dst,dst
Description The destination operand is shifted left one position as shown in Figure 3-15. The MSB is
shifted into the carry bit (C) and the LSB is filled with 0. The RLA instruction acts as a
signed multiplication by 2.
An overflow occurs if dst ≥ 04000h and dst < 0C000h before operation is performed: the
result has changed sign.
Figure 3-15. Destination Operand – Arithmetic Shift Left
An overflow occurs if dst ≥ 040h and dst < 0C0h before the operation is performed: the
result has changed sign.
Status Bits N: Set if result is negative, reset if positive
Z: Set if result is zero, reset otherwise
C: Loaded from the MSB
V: Set if an arithmetic overflow occurs:
the initial value is 04000h ≤ dst < 0C000h; reset otherwise
Set if an arithmetic overflow occurs:
the initial value is 040h ≤ dst < 0C0h; reset otherwise
Mode Bits OSCOFF, CPUOFF,and GIE are not affected.
Example R7 is multiplied by 2.
RLA R7 ; Shift left R7 (x 2)
Example The low byte of R7 is multiplied by 4.
RLA.B R7 ; Shift left low byte of R7 (x 2)
RLA.B R7 ; Shift left low byte of R7 (x 4)
NOTE: RLA Substitution
The assembler does not recognize the instruction:
RLA @R5+, RLA.B @R5+, or RLA(.B) @R5
It must be substituted by:
ADD @R5+,-2(R5), ADD.B @R5+,-1(R5), or ADD(.B) @R5
101
SLAU144J–December 2004–Revised July 2013 CPU
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