Difference between revisions of "Z80 wait instructions"
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+ | Z80 instruction set that don't change registers value (except for F register): | ||
{| class="wikitable" | {| class="wikitable" | ||
− | ! Inst. !! | + | ! Inst. !! T-S !! Bytes !! Flag modification |
|- | |- | ||
− | | <tt>NOP</tt> | + | | <tt>NOP</tt> || 5 || 1 || None |
|- | |- | ||
− | | <tt> | + | | <tt>CP (HL)</tt> || 8 || 1 || C, S, and Z flags modified by definition. P/V detects overflow. |
|- | |- | ||
− | | <tt>NOP<br/>NOP</tt> || 10 || 2 || None | + | | <tt>NOP<br/>NOP</tt> || 10 || 2 || None |
|- | |- | ||
− | | <tt> | + | | <tt>SCF<br/>RET NC</tt> || 11 || 2 || Carry flag set, H and N cleared, rest are preserved. |
|- | |- | ||
− | | <tt>BIT 0, (HL)</tt> || 14 || 2 || Opposite of the bit #0 is written into the Z flag. C is preserved, N is reset, H is set, and S and P/V are undefined. | + | | <tt>JR $+2</tt> || 13 || 2 || None |
+ | |- | ||
+ | | <tt>BIT 0,(HL)</tt> || 14 || 2 || Opposite of the bit #0 is written into the Z flag. C is preserved, N is reset, H is set, and S and P/V are undefined. | ||
+ | |- | ||
+ | | <tt>NOP<br/>NOP<br/>NOP</tt> || 15 || 3 || None | ||
+ | |- | ||
+ | | <tt>CP (HL)<BR/>CP (HL)</tt> || 16 || 2 || C, S, and Z flags modified by definition. P/V detects overflow. | ||
+ | |- | ||
+ | | <tt>SCF<br/>RET NC<br/>RET NC</tt> || 17 || 3 || Carry flag set, H and N cleared, rest are preserved. | ||
+ | |- | ||
+ | | <tt>NOP<br/>JR $+2</tt> || 18 || 3 || None | ||
+ | |- | ||
+ | | <tt>NOP<br/>BIT 0,(HL)</tt> || 19 || 3 || Opposite of the bit #0 is written into the Z flag. C is preserved, N is reset, H is set, and S and P/V are undefined. | ||
+ | |- | ||
+ | | <tt>NOP<br/>NOP<br/>NOP<br/>NOP</tt> || 20 || 4 || None | ||
+ | |- | ||
+ | | <tt>CP (IY+0)</tt> || 21 || 3 || C, S, and Z flags modified by definition. P/V detects overflow. | ||
+ | |- | ||
+ | | <tt>CP (HL)<br/>BIT 0,(HL)</tt> || 22 || 3 || C, S, and Z flags modified by definition. P/V detects overflow.<br/>Opposite of the bit #0 is written into the Z flag. C is preserved, N is reset, H is set, and S and P/V are undefined. | ||
+ | |- | ||
+ | | <tt>PUSH AF<br/>POP AF</tt> || 23 || 2 || None | ||
+ | |- | ||
+ | | <tt>CP (HL)<BR/>CP (HL)<BR/>CP (HL)</tt> || 24 || 3 || C, S, and Z flags modified by definition. P/V detects overflow. | ||
+ | |- style="background-color:lightgray;" | ||
+ | | <tt>INC (HL)<br/>DEC (HL)</tt> || 24 || 2 || Preserves C flag, N flag is reset, P/V detects overflow and rest are modified by definition.<br/>C flag preserved, P/V detects overflow and rest modified by definition.<br/>⚠️ Not interrupt safe | ||
+ | |- | ||
+ | | <tt>NOP<br/>NOP<br/>NOP<br/>NOP<br/>NOP</tt> || 25 || 5 || None | ||
+ | |- | ||
+ | | <tt>JR $+2<br/>JR $+2</tt> || 26 || 4 || None | ||
+ | |- | ||
+ | | <tt>NOP<br/>CP (HL)<br/>BIT 0,(HL)</tt> || 27 || 4 || C, S, and Z flags modified by definition. P/V detects overflow.<br/>Opposite of the bit #0 is written into the Z flag. C is preserved, N is reset, H is set, and S and P/V are undefined. | ||
+ | |- | ||
+ | | <tt>NOP<br/>PUSH AF<br/>POP AF</tt> || 28 || 3 || None | ||
+ | |- | ||
+ | | <tt>CP (IY+0)<br/>CP (HL)</tt> || 29 || 4 || C, S, and Z flags modified by definition. P/V detects overflow. | ||
+ | |- style="background-color:lightgray;" | ||
+ | | <tt>NOP<br/>INC (HL)<br/>DEC (HL)</tt> || 29 || 3 || Preserves C flag, N flag is reset, P/V detects overflow and rest are modified by definition.<br/>C flag preserved, P/V detects overflow and rest modified by definition.<br/>⚠️ Not interrupt safe | ||
+ | |- | ||
+ | | <tt>BIT 0,(HL)<br/>CP (HL)<br/>CP (HL)</tt> || 30 || 4 || Opposite of the bit #0 is written into the Z flag. C is preserved, N is reset, H is set, and S and P/V are undefined.<br/>C, S, and Z flags modified by definition. P/V detects overflow. | ||
|} | |} |
Latest revision as of 19:08, 6 April 2024
Z80 instruction set that don't change registers value (except for F register):
Inst. | T-S | Bytes | Flag modification |
---|---|---|---|
NOP | 5 | 1 | None |
CP (HL) | 8 | 1 | C, S, and Z flags modified by definition. P/V detects overflow. |
NOP NOP |
10 | 2 | None |
SCF RET NC |
11 | 2 | Carry flag set, H and N cleared, rest are preserved. |
JR $+2 | 13 | 2 | None |
BIT 0,(HL) | 14 | 2 | Opposite of the bit #0 is written into the Z flag. C is preserved, N is reset, H is set, and S and P/V are undefined. |
NOP NOP NOP |
15 | 3 | None |
CP (HL) CP (HL) |
16 | 2 | C, S, and Z flags modified by definition. P/V detects overflow. |
SCF RET NC RET NC |
17 | 3 | Carry flag set, H and N cleared, rest are preserved. |
NOP JR $+2 |
18 | 3 | None |
NOP BIT 0,(HL) |
19 | 3 | Opposite of the bit #0 is written into the Z flag. C is preserved, N is reset, H is set, and S and P/V are undefined. |
NOP NOP NOP NOP |
20 | 4 | None |
CP (IY+0) | 21 | 3 | C, S, and Z flags modified by definition. P/V detects overflow. |
CP (HL) BIT 0,(HL) |
22 | 3 | C, S, and Z flags modified by definition. P/V detects overflow. Opposite of the bit #0 is written into the Z flag. C is preserved, N is reset, H is set, and S and P/V are undefined. |
PUSH AF POP AF |
23 | 2 | None |
CP (HL) CP (HL) CP (HL) |
24 | 3 | C, S, and Z flags modified by definition. P/V detects overflow. |
INC (HL) DEC (HL) |
24 | 2 | Preserves C flag, N flag is reset, P/V detects overflow and rest are modified by definition. C flag preserved, P/V detects overflow and rest modified by definition. ⚠️ Not interrupt safe |
NOP NOP NOP NOP NOP |
25 | 5 | None |
JR $+2 JR $+2 |
26 | 4 | None |
NOP CP (HL) BIT 0,(HL) |
27 | 4 | C, S, and Z flags modified by definition. P/V detects overflow. Opposite of the bit #0 is written into the Z flag. C is preserved, N is reset, H is set, and S and P/V are undefined. |
NOP PUSH AF POP AF |
28 | 3 | None |
CP (IY+0) CP (HL) |
29 | 4 | C, S, and Z flags modified by definition. P/V detects overflow. |
NOP INC (HL) DEC (HL) |
29 | 3 | Preserves C flag, N flag is reset, P/V detects overflow and rest are modified by definition. C flag preserved, P/V detects overflow and rest modified by definition. ⚠️ Not interrupt safe |
BIT 0,(HL) CP (HL) CP (HL) |
30 | 4 | Opposite of the bit #0 is written into the Z flag. C is preserved, N is reset, H is set, and S and P/V are undefined. C, S, and Z flags modified by definition. P/V detects overflow. |