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>
137 lines
5.7 KiB
Markdown
137 lines
5.7 KiB
Markdown
# `rldimix` — Rotate Left Doubleword Immediate then Mask Insert
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> **Category:** [Integer ALU](../categories/alu.md) · **Form:** [MD](../forms/MD.md) · **Opcode:** `0x7800000c`
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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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| `rldimi` | `rldimix` | — | Rotate Left Doubleword Immediate then Mask Insert |
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| `rldimi.` | `rldimix` | Rc=1 | Rotate Left Doubleword Immediate then Mask Insert |
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## Syntax
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```asm
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rldimi[Rc] [RA], [RS], [SH], [MB]
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```
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## Encoding
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### `rldimix` — form `MD`
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- **Opcode word:** `0x7800000c`
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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` | rldimix: read | Source GPR (alias for RD in some stores). |
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| `SH` | rldimix: read | Shift amount. |
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| `MB` | rldimix: read | Mask begin bit. |
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| `RA` | rldimix: write | Source GPR (`r0`–`r31`). |
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| `CR` | rldimix: 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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### `rldimix`
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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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- `rldimix`: **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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**`rldimix`**
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- xenia-canary XML: [`tools/ppc-instructions.xml` — search for `mnem="rldimix"`](../../xenia-canary/tools/ppc-instructions.xml)
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- xenia-canary emit: [`src/xenia/cpu/ppc/ppc_emit_alu.cc:985`](../../xenia-canary/src/xenia/cpu/ppc/ppc_emit_alu.cc#L985)
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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:731`](../../xenia-rs/crates/xenia-cpu/src/decoder.rs#L731)
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- xenia-rs interpreter: [`crates/xenia-cpu/src/interpreter.rs:792-801`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L792-L801)
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<details><summary>xenia-rs interpreter body (frozen snapshot)</summary>
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```rust
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PpcOpcode::rldimix => {
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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) | (ctx.gpr[instr.ra()] & !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) | (RA & ~MASK)`.** *Reads* the prior `RA` so it can preserve the bits outside the mask — this is the only `rld*` instruction with `RA` as both source and destination.
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- **Mask is `MASK_LEFT(MB) AND MASK_RIGHT(63 - SH)`** ([`interpreter.rs:578`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L578)) — same span as [`rldicx`](rldicx.md), but the un-masked region is preserved in the destination instead of being zeroed.
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- **Use to insert a bit-field.** Common idiom: `rldimi RA, RS, b, mask_start` writes `RS`'s low (`64 - mask_start`) bits into `RA` starting at bit `b`.
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- **`SH` and `MB` decoding** is identical to the rest of the family (6-bit `sh` via `instr.sh64()`, 6-bit `mb` via the swap layout).
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- **`Rc=1` CR0 is correctly 64-bit.** Uses `as i64` directly.
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- **No `XER` effect.**
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- **Compile-time pattern.** When you see `rldimi r3, r4, n, m`, the compiler is splicing a value into `r3`; recover the meaning by computing the mask `MASK(m, 63 - n)`.
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## Related Instructions
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- [`rldicx`](rldicx.md), [`rldiclx`](rldiclx.md), [`rldicrx`](rldicrx.md) — same form family, but they zero outside the mask instead of preserving.
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- [`rlwimix`](rlwimix.md) — 32-bit insert cousin.
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- [`rldclx`](rldclx.md), [`rldcrx`](rldcrx.md) — register-shift forms (no insert variant).
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## IBM Reference
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- [AIX 7.3 — `rldimi` (Rotate Left Doubleword Immediate then Mask Insert)](https://www.ibm.com/docs/en/aix/7.3.0?topic=set-rldimi-rotate-left-double-word-immediate-then-mask-insert-instruction)
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