We've just updated MediaWiki and its underlying software. If anything doesn't look or work quite right, please mention it to us. --RanAS
BVS: Difference between revisions
From SnesLab
(added syntax) |
(control falls through) |
||
| Line 36: | Line 36: | ||
'''BVS''' is a 65x instruction that performs a branch if the [[overflow flag]] is set. | '''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. | No flags are affected. | ||
Revision as of 17:39, 14 July 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: https://archive.org/details/0893037893ProgrammingThe65816/page/n466
- Labiak page 129 on BVS: https://archive.org/details/Programming_the_65816/page/n139
- MCS6500 Manual page 41 on BVS: https://archive.org/details/mos_microcomputers_programming_manual/page/n56
- Carr page 253 on BVS: https://archive.org/details/6502UsersManual/page/n266
- Leventhal page 3-51 on BVS: https://archive.org/details/6502-assembly-language-programming/page/n100
- snes9x implementation of BVS: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1400