MSP430 Instructions
4-99
16-Bit MSP430X CPU
* 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 4−38.
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 4−38. Destination Operand—Arithmetic Shift Left
15
0
7
0
C
Byte
Word
0
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 (
×
2)
Example
The low byte of R7 is multiplied by 4.
RLA.B
R7
; Shift left low byte of R7 (
×
2)
RLA.B
R7
; Shift left low byte of R7 (
×
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
Содержание MSP430x4xx Family
Страница 1: ...MSP430x4xx Family 2007 Mixed Signal Products User s Guide SLAU056G ...
Страница 2: ......
Страница 6: ...vi ...
Страница 114: ...3 76 RISC 16 Bit CPU ...
Страница 304: ...5 20 FLL Clock Module ...
Страница 340: ...7 8 Supply Voltage Supervisor ...
Страница 348: ...8 8 16 Bit Hardware Multiplier ...
Страница 372: ...9 24 32 Bit Hardware Multiplier ...
Страница 400: ...10 28 DMA Controller ...
Страница 428: ...13 10 Basic Timer1 ...
Страница 466: ...15 24 Timer_A ...
Страница 522: ...17 30 USART Peripheral Interface UART Mode ...
Страница 544: ...18 22 USART Peripheral Interface SPI Mode ...
Страница 672: ...23 12 Comparator_A ...
Страница 692: ...24 20 LCD Controller ...
Страница 746: ...26 28 ADC12 ...