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BMI: Difference between revisions
From SnesLab
(→External Links: MCS page) |
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'''BMI''' (Branch if Minus) is a 65x instruction that performs a jump if the [[negative flag]] is set. The signed displacement of the target address can range from -128 to 127. | '''BMI''' (Branch if Minus) is a 65x instruction that performs a jump if the [[negative flag]] is set. The signed displacement of the target address can range from -128 to 127. | ||
No flags are affected. | |||
===== Cycle Penalties ===== | ===== Cycle Penalties ===== | ||
Revision as of 21:05, 6 July 2024
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | Speed | ||||
| Program Counter Relative | 30 | 2 bytes | 2 cycles* | ||||
| Flags Affected | ||||||||
|---|---|---|---|---|---|---|---|---|
| N | V | M | X | D | I | Z | C | |
| . | . | . | . | . | . | . | . | |
BMI (Branch if Minus) is a 65x instruction that performs a jump if the negative flag is set. The signed displacement of the target address can range from -128 to 127.
No flags are affected.
Cycle Penalties
- BMI takes one extra cycle if the branch is taken
- BMI takes another extra cycle if that branch crosses a page boundary in emulation mode.
See Also
External Links
- Eyes & Lichty page 432 on BMI: https://archive.org/details/0893037893ProgrammingThe65816/page/n458
- Labiak page 122 on BMI: https://archive.org/details/Programming_the_65816/page/n132
- MCS6500 Manual page 40 on BMI: https://archive.org/details/mos_microcomputers_programming_manual/page/n55
- Carr page 250 on BMI: https://archive.org/details/6502UsersManual/page/n263
- Leventhal page 3-47 on BMI: https://archive.org/details/6502-assembly-language-programming/page/n96
- snes9x implementation of BMI: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1375