Difference between revisions of "PM Opc SAR"
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(SAR Instruction) |
(→SAR = Shift Arithmetic Right) |
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(One intermediate revision by one other user not shown) | |||
Line 14: | Line 14: | ||
|12 | |12 | ||
|- | |- | ||
− | |CE 8A | + | |CE 8A nn |
|SAR [N+#nn] | |SAR [N+#nn] | ||
|20 | |20 | ||
Line 55: | Line 55: | ||
; A = 0x04 (4) | ; A = 0x04 (4) | ||
− | SAR A | + | '''SAR A''' |
; A = 0x02 (2) | ; A = 0x02 (2) | ||
; F = (Zero=0):(Carry=0):(Overflow=0):(Sign=0) | ; F = (Zero=0):(Carry=0):(Overflow=0):(Sign=0) | ||
; A = 0xFD (-4) | ; A = 0xFD (-4) | ||
− | SAR A | + | '''SAR A''' |
; A = 0xFE (-2) | ; A = 0xFE (-2) | ||
; F = (Zero=0):(Carry=0):(Overflow=0):(Sign=1) | ; F = (Zero=0):(Carry=0):(Overflow=0):(Sign=1) | ||
; B = 0x45 (69) | ; B = 0x45 (69) | ||
− | SAR B | + | '''SAR B''' |
; B = 0x22 (34) | ; B = 0x22 (34) | ||
; F = (Zero=0):(Carry=1):(Overflow=0):(Sign=0) | ; F = (Zero=0):(Carry=1):(Overflow=0):(Sign=0) | ||
; B = 0x84 (-124) | ; B = 0x84 (-124) | ||
− | SAR B | + | '''SAR B''' |
; B = 0xC2 (-62) | ; B = 0xC2 (-62) | ||
; F = (Zero=0):(Carry=0):(Overflow=0):(Sign=1) | ; F = (Zero=0):(Carry=0):(Overflow=0):(Sign=1) | ||
; [HL] = 0x01 (1) | ; [HL] = 0x01 (1) | ||
− | SAR [HL] | + | '''SAR [HL]''' |
; [HL] = 0x00 (0) | ; [HL] = 0x00 (0) | ||
; F = (Zero=1):(Carry=1):(Overflow=0):(Sign=0) | ; F = (Zero=1):(Carry=1):(Overflow=0):(Sign=0) | ||
[[PM_InstructionList|'''« Back to Instruction set''']] | [[PM_InstructionList|'''« Back to Instruction set''']] |
Latest revision as of 12:51, 27 March 2010
SAR = Shift Arithmetic Right
Hex | Mnemonic | Cycles |
---|---|---|
CE 88 | SAR A | 12 |
CE 89 | SAR B | 12 |
CE 8A nn | SAR [N+#nn] | 20 |
CE 8B | SAR [HL] | 16 |
Execute
A = Register A B = Register B [N+#nn] = Memory: (I shl 16) or (N shl 8) or #nn [HL] = Memory: (I shl 16) or HL
; SAR Ds ; ; Ds = Source/Destination Ds = (Ds AND 0x80) OR (Ds SHR 1)
Description
"8-Bits Destination" bits are arithmetically shifted right by 1.
NOTE: This instruction can be used as an signed integer division by 2.
Conditions
Zero: Set when result is 0
Carry: Set when the old bit 0 was 1
Overflow: Always Reset (there's never a overflow)
Sign: Set when bit 7 of the result is 1
Examples
; A = 0x04 (4) SAR A ; A = 0x02 (2) ; F = (Zero=0):(Carry=0):(Overflow=0):(Sign=0)
; A = 0xFD (-4) SAR A ; A = 0xFE (-2) ; F = (Zero=0):(Carry=0):(Overflow=0):(Sign=1)
; B = 0x45 (69) SAR B ; B = 0x22 (34) ; F = (Zero=0):(Carry=1):(Overflow=0):(Sign=0)
; B = 0x84 (-124) SAR B ; B = 0xC2 (-62) ; F = (Zero=0):(Carry=0):(Overflow=0):(Sign=1)
; [HL] = 0x01 (1) SAR [HL] ; [HL] = 0x00 (0) ; F = (Zero=1):(Carry=1):(Overflow=0):(Sign=0)