We've just updated MediaWiki and its underlying software. If anything doesn't look or work quite right, please mention it to us. --RanAS
XBA: Difference between revisions
From SnesLab
(nz flag behavior) |
(XBA image) |
||
| Line 39: | Line 39: | ||
The [[negative flag]] will match the most significant bit of the new low byte (A) of the accumulator. | The [[negative flag]] will match the most significant bit of the new low byte (A) of the accumulator. | ||
The [[zero flag]] will be set if and only if the new low byte (A) of the accumulator is zero, otherwise it is cleared. | The [[zero flag]] will be set if and only if the new low byte (A) of the accumulator is zero, otherwise it is cleared. | ||
[[File:xba.png]] | |||
=== See Also === | === See Also === | ||
Revision as of 20:03, 27 June 2024
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | Speed | ||||
| Implied (type 1) | EB | 1 byte | 3 cycles | ||||
| Flags Affected | |||||||
|---|---|---|---|---|---|---|---|
| N | V | M | X | D | I | Z | C |
| . | . | . | . | . | . | ||
XBA is an instruction that exchanges the high byte (B) and low byte (typically called A) of the C accumulator. It works even in 6502 emulation mode. In 65816 native mode, its standard mnemonic is still "XBA" even when the accumulator is 16-bits wide. An alternative mnemonic is "SWA."
The negative flag will match the most significant bit of the new low byte (A) of the accumulator. The zero flag will be set if and only if the new low byte (A) of the accumulator is zero, otherwise it is cleared.
See Also
External Links
- Eyes & Lichty page 524, on XBA: https://archive.org/details/0893037893ProgrammingThe65816/page/n550
- Labiak page 204 on XBA: https://archive.org/details/Programming_the_65816/page/n214
- snes9x implementation of XBA: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L3261
- undisbeliever on XBA: https://undisbeliever.net/snesdev/65816-opcodes.html#xba-exchange-the-b-and-a-accumulators