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BVC: Difference between revisions
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'''BVC''' is a 65x instruction that performs a branch if the [[overflow flag]] is clear. | '''BVC''' is a 65x instruction that performs a branch if the [[overflow flag]] is clear. If the overflow flag is set, control simply falls through to the next instruction. | ||
===== Cycle Penalties | No flags are affected. | ||
==== Syntax ==== | |||
<pre> | |||
BVC nearlabel | |||
</pre> | |||
==== Cycle Penalties ==== | |||
* BVC takes one extra cycle if the branch is taken | * BVC takes one extra cycle if the branch is taken | ||
* BVC takes another extra cycle if that branch taken crosses a page boundary in [[emulation mode]]. | * BVC takes another extra cycle if that branch taken crosses a page boundary in [[emulation mode]]. | ||
=== See Also === | === See Also === | ||
* [[BVS]] | * [[BVS]] | ||
* [[BVC (SPC700)]] | * [[BVC (SPC700)]] | ||
* [[CLV]] | |||
* [[BRA]] | |||
=== External Links === | === External Links === | ||
* [[Eyes & Lichty]] | * [[Eyes & Lichty]], [https://archive.org/details/0893037893ProgrammingThe65816/page/439 page 439] on BVC | ||
* [[Labiak]] | * [[Labiak]], [https://archive.org/details/Programming_the_65816/page/n138 page 128] on BVC | ||
* [[MCS6500 Manual]] | * 4.1.2.8 on [[MCS6500 Manual]], [https://archive.org/details/mos_microcomputers_programming_manual/page/n56 page 41] on BVC | ||
* [[Carr]] | * [[Carr]], [https://archive.org/details/6502UsersManual/page/n265 page 252] on BVC | ||
* [[Leventhal]] | * [[Leventhal]], [https://archive.org/details/6502-assembly-language-programming/page/n100 page 3-51] on BVC | ||
* snes9x implementation of BVC: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1395 | * snes9x implementation of BVC: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1395 | ||
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[[Category:Conditional Branches]] | [[Category:Conditional Branches]] | ||
[[Category:Two-byte Instructions]] | [[Category:Two-byte Instructions]] | ||
[[Category:Two-cycle Instructions]] | |||
Latest revision as of 17:42, 23 August 2024
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | Speed | ||||
| Program Counter Relative | 50 | 2 bytes | 2 cycles* | ||||
| Flags Affected | ||||||||
|---|---|---|---|---|---|---|---|---|
| N | V | M | X | D | I | Z | C | |
| . | . | . | . | . | . | . | . | |
BVC is a 65x instruction that performs a branch if the overflow flag is clear. If the overflow flag is set, control simply falls through to the next instruction.
No flags are affected.
Syntax
BVC nearlabel
Cycle Penalties
- BVC takes one extra cycle if the branch is taken
- BVC takes another extra cycle if that branch taken crosses a page boundary in emulation mode.
See Also
External Links
- Eyes & Lichty, page 439 on BVC
- Labiak, page 128 on BVC
- 4.1.2.8 on MCS6500 Manual, page 41 on BVC
- Carr, page 252 on BVC
- Leventhal, page 3-51 on BVC
- snes9x implementation of BVC: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1395