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C
19
0
MSB
0000
15
LSB
C
19
0
MSB
LSB
0
0
16
Instruction Set Description
4.6.3.29 RRUM
RRUM.A
Rotate right through carry the 20-bit CPU register content
RRUM.[W]
Rotate right through carry the 16-bit CPU register content
RRUM.A #n,Rdst
Syntax
1
≤
n
≤
4
RRUM.W #n,Rdst
or
RRUM #n,Rdst
1
≤
n
≤
4
Operation
0
→
MSB
→
MSB–1 ... LSB+1
→
LSB
→
C
Description
The destination operand is shifted right by one, two, three, or four bit positions as
shown in
. Zero is shifted into the MSB, the LSB is shifted into the carry bit.
RRUM works like an unsigned division by 2, 4, 8, or 16. The word instruction RRUM.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 unsigned address-word in R5 is divided by 16.
RRUM.A
#4,R5
; R5 = R5 » 4. R5/16
Example
The word in R6 is shifted right by one bit. The MSB R6.15 is loaded with 0.
RRUM.W
#1,R6
; R6 = R6/2. R6.19:15 = 0
Figure 4-53. Rotate Right Unsigned RRUM[.W] and RRUM.A
218
CPUX
SLAU272C – May 2011 – Revised November 2013
Copyright © 2011–2013, Texas Instruments Incorporated