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LSR: Difference between revisions
From SnesLab
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Revision as of 04:10, 20 November 2023
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | Speed | ||||
| accumulator | 4A | 1 byte | 2 cycles | ||||
| Absolute | 4E | 3 bytes | 6 cycles* | ||||
| direct page | 46 | 2 bytes | 5 cycles* | ||||
| absolute indexed X | 5E | 3 bytes | 7 cycles* | ||||
| direct page indexed X | 56 | 2 bytes | 6 cycles* | ||||
| Flags Affected | ||||||||
|---|---|---|---|---|---|---|---|---|
| N | V | M | X | D | I | Z | C | |
| 0 | . | . | . | . | . | |||
LSR (Logical Shift Right) is a 65x instruction that shifts a value one bit to the right (division by two). The most significant bit becomes a zero. The least significant bit is shifted into the carry flag. In direct page addressing modes, LSR takes another extra cycle if the low byte of the direct page register is nonzero.
See Also
External Links
- Eyes & Lichty page on LSR: https://archive.org/details/0893037893ProgrammingThe65816/page/n491
- Labiak page on LSR: https://archive.org/details/Programming_the_65816/page/n162
- MCS6500 Manual page on LSR: https://archive.org/details/mos_microcomputers_programming_manual/page/n169
- Carr page on LSR: https://archive.org/details/6502UsersManual/page/n278
- Leventhal page on LSR: https://archive.org/details/6502-assembly-language-programming/page/n125
- snes9x implementation of LSR: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L862
- undisbeliever on LSR: https://undisbeliever.net/snesdev/65816-opcodes.html#lsr-logical-shift-right