Maxim-integrated DS4830A Optical Microcontroller Instrukcja Użytkownika Pobierz pdf (Strona 226)

DS4830A User’s Guide

226

SR Shift Accumulator Right

SRA / SRA2 / SRA4 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 msb while the SRA, SRA2, and SRA4 instructions effectively shift a copy of the

current msb into the accumulator, thereby preserving any sign orientation. For each shift

iteration, the accumulator lsb 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

Acc.15  0; Acc.[14:0] Acc.[15:1]; C  Acc.0

Encoding: 15 0

1000

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

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Maxim-integrated DS4830A Optical Microcontroller Instrukcja Użytkownika Strona 226