chore: add migration/ bundle for cross-machine setup
Bundles state that lives OUTSIDE the xenia-rs repo so a fresh clone on
another machine can be brought up to identical configuration via
migration/setup.sh:
- claude-memory/ ~/.claude/projects/-home-fabi-RE-Project-Sylpheed/memory/
(103 files, 1.1 MB - MEMORY.md + every
project_xenia_rs_*.md from audits
addis_signext through audit-058)
- project-root/dot-claude/ <project-root>/.claude/settings.json
(Stop hook + permissions)
- project-root/ppc-manual/ <project-root>/ppc-manual/
(PowerPC reference docs, 397 files, 3.7 MB)
- project-root/run-canary.sh <project-root>/run-canary.sh
- README.md Human-readable setup checklist
- setup.sh Idempotent installer (also reclones
xenia-canary at pinned HEAD 6de80dffe)
- MANIFEST.md Per-file mapping + per-file-not-bundled
restoration recipe
Excluded from bundle (not shippable via git):
- Sylpheed ISO (7.8 GB; copyright; manual copy required)
- sylpheed.db (395 MB; regenerable from XEX via analysis tooling)
- target/ build artifacts (rebuild on target)
- audit-runs probe firehoses (.log/.stdout/.stderr ~11 GB; rerun if needed)
- audit-runs memory dumps (.bin ~4.5 GB; rerun audit-026/027/029 if needed)
- xenia-canary checkout (setup.sh reclones from
git.mc02.dev/fabi/Xenia-Canary.git at HEAD 6de80dffe)
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
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migration/project-root/ppc-manual/alu/rldcrx.md
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migration/project-root/ppc-manual/alu/rldcrx.md
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# `rldcrx` — Rotate Left Doubleword then Clear Right
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> **Category:** [Integer ALU](../categories/alu.md) · **Form:** [MDS](../forms/MDS.md) · **Opcode:** `0x78000012`
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<!-- GENERATED: BEGIN -->
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## Assembler Mnemonics
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| Mnemonic | XML entry | Flags | Description |
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| --- | --- | --- | --- |
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| `rldcr` | `rldcrx` | — | Rotate Left Doubleword then Clear Right |
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| `rldcr.` | `rldcrx` | Rc=1 | Rotate Left Doubleword then Clear Right |
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## Syntax
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```asm
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rldcr[Rc] [RA], [RS], [RB], [ME]
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```
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## Encoding
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### `rldcrx` — form `MDS`
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- **Opcode word:** `0x78000012`
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- **Primary opcode (bits 0–5):** `30`
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- **Extended opcode:** —
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- **Synchronising:** no
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| Bits | Field | Meaning |
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| --- | --- | --- |
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| 0–5 | `OPCD` | primary opcode (30) |
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| 6–10 | `RS` | source GPR |
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| 11–15 | `RA` | destination GPR |
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| 16–20 | `RB` | source B GPR |
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| 21–26 | `mb/me` | 6-bit mask field (swapped halves) |
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| 27–30 | `XO` | extended opcode |
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| 31 | `Rc` | record-form flag |
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## Operands
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| Field | Role | Description |
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| --- | --- | --- |
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| `RS` | rldcrx: read | Source GPR (alias for RD in some stores). |
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| `RB` | rldcrx: read | Source GPR. |
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| `ME` | rldcrx: read | Mask end bit. |
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| `RA` | rldcrx: write | Source GPR (`r0`–`r31`). |
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| `CR` | rldcrx: write (conditional) | Condition-register update. When `Rc=1`, CR field 0 (or CR6 for vector compares, CR1 for FPU) is updated from the result. |
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## Register Effects
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### `rldcrx`
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- **Reads (always):** `RS`, `RB`, `ME`
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- **Reads (conditional):** _none_
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- **Writes (always):** `RA`
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- **Writes (conditional):** `CR`
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## Status-Register Effects
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- `rldcrx`: **CR0** ← signed-compare(result, 0) with `SO ← XER[SO]`, when `Rc=1`.
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## Operation (pseudocode)
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```
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; Pseudocode derives directly from the xenia-rs interpreter
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; arm (see Implementation References). Operation semantics:
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; - Read source operands from the fields listed under Operands.
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; - Apply the arithmetic / logical / memory action described
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; in the Description field above.
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; - Write results to the destination register(s); update any
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; status bits enumerated under Status-Register Effects.
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; Consult the IBM AIX reference link under IBM Reference for
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; canonical PPC-style pseudocode where xenia's expression is
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; terse.
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```
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## C Translation Example
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```c
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/* C translation: the xenia-rs interpreter arm below in */
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/* Implementation References is the authoritative semantic */
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/* snapshot. Translate it line-by-line: */
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/* - ctx.gpr[N] -> r[N] (or f[]/v[] for FPRs/VRs) */
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/* - mem.read_u*/write_u* -> mem_read_u*_be / mem_write_u*_be */
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/* - ctx.update_cr_signed(fld, v) -> update_cr_signed(fld, v) */
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/* - ctx.xer_ca / xer_ov / xer_so -> xer.CA / xer.OV / xer.SO */
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/* The Register Effects and Status-Register Effects tables above */
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/* enumerate every side effect a faithful translation must emit. */
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```
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## Implementation References
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**`rldcrx`**
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- xenia-canary XML: [`tools/ppc-instructions.xml` — search for `mnem="rldcrx"`](../../xenia-canary/tools/ppc-instructions.xml)
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- xenia-canary emit: [`src/xenia/cpu/ppc/ppc_emit_alu.cc:881`](../../xenia-canary/src/xenia/cpu/ppc/ppc_emit_alu.cc#L881)
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- xenia-rs opcode: [`crates/xenia-cpu/src/opcode.rs:61`](../../xenia-rs/crates/xenia-cpu/src/opcode.rs#L61)
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- xenia-rs decoder: [`crates/xenia-cpu/src/decoder.rs:734`](../../xenia-rs/crates/xenia-cpu/src/decoder.rs#L734)
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- xenia-rs interpreter: [`crates/xenia-cpu/src/interpreter.rs:812-821`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L812-L821)
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<details><summary>xenia-rs interpreter body (frozen snapshot)</summary>
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```rust
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PpcOpcode::rldcrx => {
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let rs = ctx.gpr[instr.rs()];
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let sh = ctx.gpr[instr.rb()] & 0x3F;
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let me = instr.mb_md();
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let rotated = rs.rotate_left(sh as u32);
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let mask = rld_mask_right(me);
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ctx.gpr[instr.ra()] = rotated & mask;
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if instr.rc_bit() { ctx.update_cr_signed(0, ctx.gpr[instr.ra()] as i64); }
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ctx.pc += 4;
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}
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```
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</details>
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<!-- GENERATED: END -->
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## Special Cases & Edge Conditions
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- **`RA ← ROTL64(RS, RB[58:63]) & MASK(0, ME)`.** Rotate `RS` left by `RB & 0x3F`, then *clear* bits to the right of `ME` — keep bits `0..ME`, force bits `ME+1..63` to zero.
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- **Shift from register.** Same as [`rldclx`](rldclx.md): only the low 6 bits of `RB` count.
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- **`ME` is a split 6-bit field.** Same swap-decoded layout as `MB` in `rldclx`: `(instr.mb() << 1) | ((raw >> 1) & 1)` ([`interpreter.rs:597`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L597)). Note that even though it represents `ME` here, xenia reads it from `instr.mb()` because the field shares the same encoding slot.
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- **Mask generation.** `rld_mask_right(ME)` = `~((1 << (63 - ME)) - 1)` keeping bits `0..ME`. When `ME = 63` the mask is all ones; when `ME = 0` only bit 0 survives.
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- **`Rc=1` CR0 is correctly 64-bit.** Uses `as i64` directly ([`interpreter.rs:602`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L602)).
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- **No `XER` effect.**
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- **Useful for left-shift with arbitrary discard.** `rldcr RA, RS, RB, 63 - n` is functionally close to a left-shift-and-mask sequence, with the rotate variant additionally allowing wrap-around.
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## Related Instructions
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- [`rldclx`](rldclx.md) — sister: clear *left* instead of right.
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- [`rldicrx`](rldicrx.md) — immediate-shift form.
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- [`rldicx`](rldicx.md), [`rldiclx`](rldiclx.md), [`rldimix`](rldimix.md) — full immediate rotate-and-mask family.
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- [`sldx`](sldx.md) — plain 64-bit logical left shift (often a strength-reduced equivalent).
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## IBM Reference
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- [AIX 7.3 — `rldcr` (Rotate Left Doubleword then Clear Right)](https://www.ibm.com/docs/en/aix/7.3.0?topic=set-rldcr-rotate-left-double-word-then-clear-right-instruction)
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