Nintendo GAME BOY Programming Manual page 113

SRL
Shifts the contents of operand m to the right. That is, the contents of bit 7 are copied to bit 6 and the
previous contents of bit 6 (the contents before the copy operation) are copied to bit 5. The same
operation is repeated in sequence for the rest of the operand . The contents of bit 0 are copied to CY,
and bit 7 is reset.
r and (HL) are used for operand m.
Examples: When A = 01h, (HL) = FFh, CY + 0,
SRL A ; A ← 00h, CY ← 1, Z ← 1, H ← 0, N ← 0
SRL (HL) ; (HL) ← 7Fh, CY ← 1, Z ← 0, H ← 0, N ← 0
SWAP
Shifts the contents of the lower-order 4 bits (0-3) of operand m unmodified to the higher-order 4 bits (4-7)
of that operand and shifts the contents of the higher-order 4 bits to the lower-order 4 bits.
r and (HL) are used for operand m.
Examples: When A = 00h and (HL) = F0h,
SWAP A ; A ← 00h, Z ← 1, H ← 0, N ← 0, CY ← 0
SWAP (HL) ; (HL) ← 0Fh, Z ← 0, H ← 0, N ← 0, CY ← 0
m
0
7
SRL r
SRL (HL)
m
7
SWAP r
SWAP (HL)
m
m
CY
0
5 4 3
CYCL 7 6
2 11 001
00 111
4 11 001
00 111
0
4 3 0
5 4 3
CYCL 7 6
2 11 001
00 110
4 11 001
00 110
113
Chapter 4: CPU Instruction Set
CY H N Z CYCL
0 0 * --
0
2 1 0
011
r
011
110
CY H N Z CYCL
0 0 * --
2 1 0
011
r
011
110
7 6 5 4 3 2 1 0
-- -- --
7 6 5 4 3 2 1 0
-- -- --