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BMI: Difference between revisions
From SnesLab
(displacement) |
(linkify flags) |
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| Line 16: | Line 16: | ||
!colspan="9"|Flags Affected | !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]] | ||
|+ | |+ | ||
|. | |. | ||
Revision as of 04:07, 27 November 2023
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | Speed | ||||
| relative | 30 | 2 byte | 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.
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 on BMI: https://archive.org/details/0893037893ProgrammingThe65816/page/n458
- Labiak page on BMI: https://archive.org/details/Programming_the_65816/page/n132
- MCS6500 Manual page on BMI: https://archive.org/details/mos_microcomputers_programming_manual/page/n55
- Carr page on BMI: https://archive.org/details/6502UsersManual/page/n263
- Leventhal page 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