e6d43a23ac
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>
139 lines
5.8 KiB
Markdown
139 lines
5.8 KiB
Markdown
# `rldicx` — Rotate Left Doubleword Immediate then Clear
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> **Category:** [Integer ALU](../categories/alu.md) · **Form:** [MD](../forms/MD.md) · **Opcode:** `0x78000008`
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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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| `rldic` | `rldicx` | — | Rotate Left Doubleword Immediate then Clear |
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| `rldic.` | `rldicx` | Rc=1 | Rotate Left Doubleword Immediate then Clear |
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## Syntax
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```asm
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rldic[Rc] [RA], [RS], [SH], [MB]
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```
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## Encoding
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### `rldicx` — form `MD`
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- **Opcode word:** `0x78000008`
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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 | `sh` | shift amount low 5 bits |
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| 21–26 | `mb/me` | 6-bit mask field (swapped halves) |
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| 27–29 | `XO` | extended opcode |
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| 30 | `sh5` | shift amount high bit |
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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` | rldicx: read | Source GPR (alias for RD in some stores). |
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| `SH` | rldicx: read | Shift amount. |
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| `MB` | rldicx: read | Mask begin bit. |
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| `RA` | rldicx: write | Source GPR (`r0`–`r31`). |
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| `CR` | rldicx: 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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### `rldicx`
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- **Reads (always):** `RS`, `SH`, `MB`
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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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- `rldicx`: **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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**`rldicx`**
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- xenia-canary XML: [`tools/ppc-instructions.xml` — search for `mnem="rldicx"`](../../xenia-canary/tools/ppc-instructions.xml)
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- xenia-canary emit: [`src/xenia/cpu/ppc/ppc_emit_alu.cc:906`](../../xenia-canary/src/xenia/cpu/ppc/ppc_emit_alu.cc#L906)
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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:730`](../../xenia-rs/crates/xenia-cpu/src/decoder.rs#L730)
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- xenia-rs interpreter: [`crates/xenia-cpu/src/interpreter.rs:782-791`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L782-L791)
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<details><summary>xenia-rs interpreter body (frozen snapshot)</summary>
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```rust
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PpcOpcode::rldicx => {
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let rs = ctx.gpr[instr.rs()];
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let sh = instr.sh64();
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let mb = instr.mb_md();
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let rotated = rs.rotate_left(sh);
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let mask = rld_mask_left(mb) & rld_mask_right(63 - sh);
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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, SH) & MASK(MB, 63 - SH)`.** Rotate `RS` left by `SH` bits, then mask off both ends: clear bits `0..MB-1` *and* clear bits `64-SH..63`. This is the "clear at both edges" variant — useful for inserting a field into an otherwise-zero register.
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- **`SH` is a 6-bit immediate** spanning bits 16–20 plus bit 30 of the instruction word. Xenia uses the helper `instr.sh64()` ([`interpreter.rs:566`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L566)) to assemble the 6 bits.
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- **`MB` is also 6-bit, split-encoded** like the rest of the `rld*` family: `(instr.mb() << 1) | ((raw >> 1) & 1)`.
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- **Mask is computed as `MASK_LEFT(MB) AND MASK_RIGHT(63 - SH)`.** This produces the equivalent of "left-shift `RS` by `SH` then clear high bits above bit `MB`" — a common pattern when `MB ≤ 63 - SH`.
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- **Equivalent to a logical shift when `MB = 0`.** `rldic RA, RS, SH, 0` ≡ `sldi RA, RS, SH` (an alias the assembler may prefer).
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- **`Rc=1` CR0 is correctly 64-bit.** [`interpreter.rs:571`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L571) uses `as i64` directly.
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- **No `XER` effect.**
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## Related Instructions
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- [`rldiclx`](rldiclx.md), [`rldicrx`](rldicrx.md) — clear-only-one-side variants.
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- [`rldclx`](rldclx.md), [`rldcrx`](rldcrx.md) — register-shift forms.
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- [`rldimix`](rldimix.md) — insert under mask.
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- [`rlwinmx`](rlwinmx.md) — 32-bit cousin.
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- `sldi` (simplified) — `rldic RA, RS, n, 0`; assemblers prefer this for plain logical left shifts.
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## IBM Reference
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- [AIX 7.3 — `rldic` (Rotate Left Doubleword Immediate then Clear)](https://www.ibm.com/docs/en/aix/7.3.0?topic=set-rldic-rotate-left-double-word-immediate-then-clear-instruction)
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