Difference between revisions of "PM Opc SAR"
From SublabWiki
(SAR Instruction) |
m (→Examples) |
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; 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''']] |
Revision as of 00:29, 21 April 2009
SAR = Shift Arithmetic Right
Hex | Mnemonic | Cycles |
---|---|---|
CE 88 | SAR A | 12 |
CE 89 | SAR B | 12 |
CE 8A | 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)