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BVS: Difference between revisions
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''' | {| class="wikitable" style="float:right;clear:right;width:40%" | ||
!colspan="8"|Basic Info | |||
|+ | |||
|'''Addressing Mode''' | |||
|'''Opcode''' | |||
|'''Length''' | |||
|'''Speed''' | |||
|+ | |||
|[[Program Counter Relative]] | |||
|70 | |||
|2 bytes | |||
|2 cycles* | |||
|} | |||
{| 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]] | ||
|+ | |+ | ||
|. | |. | ||
| Line 22: | Line 34: | ||
|. | |. | ||
|} | |} | ||
'''BVS''' is a 65x instruction that performs a branch if the [[overflow flag]] is set. | |||
If the overflow flag is clear, control simply falls through to the next instruction. | |||
No flags are affected. | |||
==== Syntax ==== | |||
<pre> | |||
BVS nearlabel | |||
</pre> | |||
==== Cycle Penalties ==== | |||
* BVS takes one extra cycle if the branch is taken | |||
* BVS takes another extra cycle if that branch taken crosses a page boundary in [[emulation mode]]. | |||
=== See Also === | |||
* [[BVC]] | |||
* [[BVS (SPC700)]] | |||
* [[BRA]] | |||
* [[CLV]] | |||
=== External Links === | === External Links === | ||
* [[Eyes & Lichty]] page on BVS: https://archive.org/details/ | * [[Eyes & Lichty]], [https://archive.org/details/0893037893ProgrammingThe65816/page/440 page 440] on BVS | ||
* [[Labiak]], [https://archive.org/details/Programming_the_65816/page/n139 page 129] on BVS | |||
* 4.1.2.7 on [[MCS6500 Manual]], [https://archive.org/details/mos_microcomputers_programming_manual/page/n56 page 41] on BVS | |||
* [[Carr]], [https://archive.org/details/6502UsersManual/page/n266 page 253] on BVS | |||
* [[Leventhal]], [https://archive.org/details/6502-assembly-language-programming/page/n100 page 3-51] on BVS | |||
* snes9x implementation of BVS: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1400 | |||
[[Category:ASM]] | [[Category:ASM]] | ||
[[Category:Inherited from 6502]] | [[Category:Inherited from 6502]] | ||
[[Category:Conditional Branches]] | |||
[[Category:Two-byte Instructions]] | |||
Latest revision as of 17:42, 23 August 2024
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | Speed | ||||
| Program Counter Relative | 70 | 2 bytes | 2 cycles* | ||||
| Flags Affected | ||||||||
|---|---|---|---|---|---|---|---|---|
| N | V | M | X | D | I | Z | C | |
| . | . | . | . | . | . | . | . | |
BVS is a 65x instruction that performs a branch if the overflow flag is set.
If the overflow flag is clear, control simply falls through to the next instruction.
No flags are affected.
Syntax
BVS nearlabel
Cycle Penalties
- BVS takes one extra cycle if the branch is taken
- BVS takes another extra cycle if that branch taken crosses a page boundary in emulation mode.
See Also
External Links
- Eyes & Lichty, page 440 on BVS
- Labiak, page 129 on BVS
- 4.1.2.7 on MCS6500 Manual, page 41 on BVS
- Carr, page 253 on BVS
- Leventhal, page 3-51 on BVS
- snes9x implementation of BVS: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1400