Extended Instructions
4-139
16-Bit MSP430X CPU
RRAM.A
Rotate Right Arithmetically the 20-bit CPU register content
RRAM[.W]
Rotate Right Arithmetically the 16-bit CPU register content
Syntax
RRAM.A
#n,Rdst
1
≤
n
≤
4
RRAM.W
#n,Rdst
or RRAM #n,Rdst
1
≤
n
≤
4
Operation
MSB
→
MSB
→
MSB
-
1
…
. LSB+1
→
LSB
→
C
Description
The destination operand is shifted right arithmetically by one, two, three, or
four bit positions as shown in Figure 4−47. The MSB retains its value (sign).
RRAM operates equal to a signed division by 2/4/8/16. The MSB is retained
and shifted into MSB
-
1. The LSB+1 is shifted into the LSB, and the LSB is
shifted into the carry bit C. The word instruction RRAM.W clears the bits
Rdst.19:16.
Note : This instruction does not use the extension word.
Status Bits
N:
Set if result is negative
.A: Rdst.19 = 1, reset if Rdst.19 = 0
.W: Rdst.15 = 1, reset if Rdst.15 = 0
Z:
Set if result is zero, reset otherwise
C: Loaded
from the LSB (n = 1), LSB+1 (n = 2), LSB+2 (n = 3), or LSB+3
(n = 4)
V: Reset
Mode Bits
OSCOFF, CPUOFF, and GIE are not affected.
Example
The signed 20-bit number in R5 is shifted arithmetically right two positions.
RRAM.A
#2,R5
; R5/4 -> R5
Example
The signed 20-bit value in R15 is multiplied by 0.75. (0.5 + 0.25) x R15
PUSHM.A
#1,R15
; Save extended R15 on stack
RRAM.A
#1,R15
; R15
×
0.5 -> R15
ADDX.A
@SP+,R15
; R15
×
0.5 + R15 = 1.5
×
R15 -> R15
RRAM.A
#1,R15
; (1.5
×
R15)
×
0.5 = 0.75
×
R15 -> R15
Figure 4−47. Rotate Right Arithmetically RRAM[.W] and RRAM.A
C
19
0
MSB
0000
15
LSB
C
19
0
MSB
LSB
16
Summary of Contents for MSP430x4xx Family
Page 1: ...MSP430x4xx Family 2007 Mixed Signal Products User s Guide SLAU056G ...
Page 2: ......
Page 6: ...vi ...
Page 114: ...3 76 RISC 16 Bit CPU ...
Page 304: ...5 20 FLL Clock Module ...
Page 340: ...7 8 Supply Voltage Supervisor ...
Page 348: ...8 8 16 Bit Hardware Multiplier ...
Page 372: ...9 24 32 Bit Hardware Multiplier ...
Page 400: ...10 28 DMA Controller ...
Page 428: ...13 10 Basic Timer1 ...
Page 466: ...15 24 Timer_A ...
Page 522: ...17 30 USART Peripheral Interface UART Mode ...
Page 544: ...18 22 USART Peripheral Interface SPI Mode ...
Page 672: ...23 12 Comparator_A ...
Page 692: ...24 20 LCD Controller ...
Page 746: ...26 28 ADC12 ...