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S3C8248/C8245/P8245/C8247/C8249/P8249
SRA
— Shift Right Arithmetic
SRA
dst
dst (7) ← dst (7)
Operation:
C ← dst (0)
dst (n) ← dst (n + 1), n = 0–6
An arithmetic shift-right of one bit position is performed on the destination operand. Bit zero (the
LSB) replaces the carry flag. The value of bit 7 (the sign bit) is unchanged and is shifted into bit
position 6.
Flags:
C: Set if the bit shifted from the LSB position (bit zero) was "1".
Z: Set if the result is "0"; cleared otherwise.
S: Set if the result is negative; cleared otherwise.
V: Always cleared to "0".
D: Unaffected.
H: Unaffected.
Format:
opc
Examples:
Given: Register 00H = 9AH, register 02H = 03H, register 03H = 0BCH, and C = "1":
SRA
SRA
In the first example, if general register 00H contains the value 9AH (10011010B), the statement
"SRA 00H" shifts the bit values in register 00H right one bit position. Bit zero ("0") clears the C
flag and bit 7 ("1") is then shifted into the bit 6 position (bit 7 remains unchanged). This leaves
the value 0CDH (11001101B) in destination register 00H.
C
dst
→
00H
Register 00H = 0CD, C = "0"
→
@02H
Register 02H = 03H, register 03H = 0DEH, C = "0"
7
6
0
Bytes
2
INSTRUCTION SET
Cycles
Opcode
(Hex)
4
D0
4
D1
Addr Mode
dst
R
IR
6-79
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