Maxim Integrated MAXQ610 - Manual (Page 190)

14-23
MAXQ610 User’s Guide
SR
SRA/SRA2/SRA4 Shift Accumulator Right
Shift Accumulator Right Arithmetically One, Two, or Four Times
Description: Shifts the active accumulator right once for the SR, SRA instructions and 2 or 4 times respectively
for the SRA2, SRA4 instructions . The SR instruction shifts a 0 into the accumulator msbit while the
SRA, SRA2, and SRA4 instructions effectively shift a copy of the current msbit into the accumulator,
thereby preserving any sign orientation . For each shift iteration, the accumulator lsbit is shifted into
the Carry (C) flag .
Status Flags: C, S (changes for SR only), Z
SR Operation: 15 Active Accumulator (Acc) 0 Carry Flag
0
→ → →
Acc .15 ← 0; Acc .[14:0] ← Acc .[15:1]; C ← Acc .0
Encoding: 15 0
1000 1010 1010 1010
Example(s): ; Acc = A345h, C=1, S=1, Z=0
SR ; Acc = 51A2h, C=1, S=0, Z=0
SR ; Acc = 28D1h, C=0, S=0, Z=0
SRA Operation: 15 Active Accumulator (Acc) 0 Carry Flag
→ → →
Acc .[14:0] ← Acc .[15:1]
Acc .15 ← Acc .15
C ← Acc .0
Encoding: 15 0
1000 1010 1111 1010
Example(s): ; Acc = 0003h, C=0, Z=0
SRA ; Acc = 0001h, C=1, Z=0
SRA ; Acc = 0000h, C=1, Z=1
SRA2 Operation: 15 Active Accumulator (Acc) 0 Carry Flag
→ → →
Acc .[13:0] ← Acc .[15:2]
Acc .[15:14] ← Acc .15
C ← Acc .1
Encoding: 15 0
1000 1010 1110 1010
Example(s): ; Acc = 0003h, C=0, Z=0
SRA2 ; Acc = 0000h, C=1, Z=1