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BEQ: Difference between revisions
From SnesLab
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|'''Speed''' | |'''Speed''' | ||
|+ | |+ | ||
| | |[[Program Counter Relative]] | ||
|F0 | |F0 | ||
|2 byte | |2 byte | ||
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{| class="wikitable" style="float:right;clear:right;width:30%" | {| class="wikitable" style="float:right;clear:right;width:30%" | ||
!colspan="9"|Flags | !colspan="9"|Flags Affected | ||
|+ | |+ | ||
|N | |[[Negative Flag|N]] | ||
|V | |[[Overflow Flag|V]] | ||
|M | |[[M Flag|M]] | ||
|X | |[[X Flag|X]] | ||
|D | |[[Decimal Flag|D]] | ||
|I | |[[I Flag|I]] | ||
|Z | |[[Zero Flag|Z]] | ||
|C | |[[Carry Flag|C]] | ||
|+ | |+ | ||
|. | |. | ||
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'''BEQ''' (Branch if Equal) is a 65x instruction that performs a jump if the [[zero flag]] is set. | '''BEQ''' (Branch if Equal) is a 65x instruction that performs a jump if the [[zero flag]] is set. | ||
===== Cycle Penalties ===== | |||
* BEQ takes an extra cycle if the branch is taken | |||
* BEQ takes another extra cycle if the branch taken crosses a page boundary in [[emulation mode]] | |||
=== See Also === | === See Also === | ||
Line 43: | Line 47: | ||
=== External Links === | === External Links === | ||
* [[Eyes & Lichty]] page 430, on BEQ: https://archive.org/details/0893037893ProgrammingThe65816/page/n456 | * [[Eyes & Lichty]] page 430, on BEQ: https://archive.org/details/0893037893ProgrammingThe65816/page/n456 | ||
* [[Labiak]] page on BEQ: https://archive.org/details/Programming_the_65816/page/n130 | * [[Labiak]] page 120 on BEQ: https://archive.org/details/Programming_the_65816/page/n130 | ||
* [[MCS6500 Manual]] page on BEQ: https://archive.org/details/mos_microcomputers_programming_manual/page/n56 | * [[MCS6500 Manual]] page 41 on BEQ: https://archive.org/details/mos_microcomputers_programming_manual/page/n56 | ||
* [[Carr]] page on BEQ: https://archive.org/details/6502UsersManual/page/n262 | * [[Carr]] page 249 on BEQ: https://archive.org/details/6502UsersManual/page/n262 | ||
* [[Leventhal]] page on BEQ: https://archive.org/details/6502-assembly-language-programming/page/n93 | * [[Leventhal]] page 3-44 on BEQ: https://archive.org/details/6502-assembly-language-programming/page/n93 | ||
* snes9x implementation of BEQ: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1370 | * snes9x implementation of BEQ: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1370 | ||
[[Category:ASM]] | [[Category:ASM]] | ||
[[Category:Inherited from 6502]] | [[Category:Inherited from 6502]] | ||
[[Category:Conditional Branches]] | |||
[[Category:Two-byte Instructions]] |
Latest revision as of 04:39, 6 December 2023
Basic Info | |||||||
---|---|---|---|---|---|---|---|
Addressing Mode | Opcode | Length | Speed | ||||
Program Counter Relative | F0 | 2 byte | 2 cycles |
Flags Affected | ||||||||
---|---|---|---|---|---|---|---|---|
N | V | M | X | D | I | Z | C | |
. | . | . | . | . | . | . | . |
BEQ (Branch if Equal) is a 65x instruction that performs a jump if the zero flag is set.
Cycle Penalties
- BEQ takes an extra cycle if the branch is taken
- BEQ takes another extra cycle if the branch taken crosses a page boundary in emulation mode
See Also
External Links
- Eyes & Lichty page 430, on BEQ: https://archive.org/details/0893037893ProgrammingThe65816/page/n456
- Labiak page 120 on BEQ: https://archive.org/details/Programming_the_65816/page/n130
- MCS6500 Manual page 41 on BEQ: https://archive.org/details/mos_microcomputers_programming_manual/page/n56
- Carr page 249 on BEQ: https://archive.org/details/6502UsersManual/page/n262
- Leventhal page 3-44 on BEQ: https://archive.org/details/6502-assembly-language-programming/page/n93
- snes9x implementation of BEQ: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1370