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>
173 lines
7.2 KiB
Markdown
173 lines
7.2 KiB
Markdown
# `lvlx` — Load Vector Left Indexed
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> **Category:** [Memory](../categories/memory.md) · **Form:** [X](../forms/X.md) · **Opcode:** `0x7c00040e`
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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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| `lvlx` | `lvlx` | — | Load Vector Left Indexed |
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| `lvlx128` | `lvlx128` | — | Load Vector Left Indexed 128 |
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## Syntax
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```asm
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lvlx [VD], [RA0], [RB]
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lvlx128 [VD], [RA0], [RB]
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```
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## Encoding
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### `lvlx` — form `X`
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- **Opcode word:** `0x7c00040e`
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- **Primary opcode (bits 0–5):** `31`
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- **Extended opcode:** `519`
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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 |
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| 6–10 | `RT/FRT/VRT` | destination |
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| 11–15 | `RA/FRA/VRA` | source A |
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| 16–20 | `RB/FRB/VRB` | source B |
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| 21–30 | `XO` | extended opcode (10 bits) |
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| 31 | `Rc` | record-form flag |
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### `lvlx128` — form `VX128_1`
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- **Opcode word:** `0x10000403`
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- **Primary opcode (bits 0–5):** `4`
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- **Extended opcode:** `1027`
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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 (4) |
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| 6–10 | `VD128l` | destination low 5 bits |
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| 11–15 | `RA` | address register |
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| 16–20 | `RB` | offset register |
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| 21–27 | `XO` | extended opcode |
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| 28–29 | `VD128h` | destination high 2 bits |
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| 30–31 | `—` | reserved |
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## Operands
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| Field | Role | Description |
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| --- | --- | --- |
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| `RA0` | lvlx: read; lvlx128: read | Source GPR; when the encoded register number is 0 the operand is the literal 64-bit zero, **not** `r0`. |
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| `RB` | lvlx: read; lvlx128: read | Source GPR. |
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| `VD` | lvlx: write; lvlx128: write | Destination vector register. |
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## Register Effects
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### `lvlx`
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- **Reads (always):** `RA0`, `RB`
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- **Reads (conditional):** _none_
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- **Writes (always):** `VD`
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- **Writes (conditional):** _none_
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### `lvlx128`
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- **Reads (always):** `RA0`, `RB`
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- **Reads (conditional):** _none_
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- **Writes (always):** `VD`
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- **Writes (conditional):** _none_
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## Status-Register Effects
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_No condition-register or status-register effects._
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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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**`lvlx`**
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- xenia-canary XML: [`tools/ppc-instructions.xml` — search for `mnem="lvlx"`](../../xenia-canary/tools/ppc-instructions.xml)
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- xenia-canary emit: [`src/xenia/cpu/ppc/ppc_emit_altivec.cc:216`](../../xenia-canary/src/xenia/cpu/ppc/ppc_emit_altivec.cc#L216)
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- xenia-rs opcode: [`crates/xenia-cpu/src/opcode.rs:44`](../../xenia-rs/crates/xenia-cpu/src/opcode.rs#L44)
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- xenia-rs decoder: [`crates/xenia-cpu/src/decoder.rs:815`](../../xenia-rs/crates/xenia-cpu/src/decoder.rs#L815)
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- xenia-rs interpreter: [`crates/xenia-cpu/src/interpreter.rs:3083-3087`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L3083-L3087)
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<details><summary>xenia-rs interpreter body (frozen snapshot)</summary>
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```rust
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PpcOpcode::lvlx | PpcOpcode::lvlxl => {
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let ea = ea_indexed(ctx, instr);
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ctx.vr[instr.rd()] = crate::vmx::load_vector_left(mem, ea);
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ctx.pc += 4;
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}
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```
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</details>
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**`lvlx128`**
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- xenia-canary XML: [`tools/ppc-instructions.xml` — search for `mnem="lvlx128"`](../../xenia-canary/tools/ppc-instructions.xml)
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- xenia-canary emit: [`src/xenia/cpu/ppc/ppc_emit_altivec.cc:219`](../../xenia-canary/src/xenia/cpu/ppc/ppc_emit_altivec.cc#L219)
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- xenia-rs opcode: [`crates/xenia-cpu/src/opcode.rs:44`](../../xenia-rs/crates/xenia-cpu/src/opcode.rs#L44)
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- xenia-rs decoder: [`crates/xenia-cpu/src/decoder.rs:420`](../../xenia-rs/crates/xenia-cpu/src/decoder.rs#L420)
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- xenia-rs interpreter: [`crates/xenia-cpu/src/interpreter.rs:3088-3092`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L3088-L3092)
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<details><summary>xenia-rs interpreter body (frozen snapshot)</summary>
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```rust
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PpcOpcode::lvlx128 | PpcOpcode::lvlxl128 => {
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let ea = ea_indexed(ctx, instr);
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ctx.vr[instr.vd128()] = crate::vmx::load_vector_left(mem, ea);
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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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- **Load-left half of an unaligned vector.** `lvlx` reads `(16 - (EA mod 16))` bytes starting at the **exact** `EA` and places them in the **left** (high-address-byte → low-lane) of the destination vector; the remaining lanes on the right are zero-filled. Combine with `lvrx` at `EA + 15` to assemble a full unaligned vector across an alignment boundary.
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- **Companion idiom.** `lvlx VD, RA, RB ; lvrx Vtemp, RA, RB ; vor VD, VD, Vtemp` produces the unaligned 16 bytes at `EA` regardless of alignment. This was the canonical unaligned-vector-read recipe before `lvsl`/`vperm` shuffles became the more common idiom.
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- **No alignment masking.** Unlike `lvx`, the EA is **not** rounded down. `EA mod 16` controls how the data is shifted into the destination.
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- **`RA0` semantics.** `RA = 0` selects literal zero.
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- **Microsoft Xbox 360 specific.** `lvlx` and `lvrx` are not in the standard Altivec specification — they are part of Microsoft's VMX128 / Cell BE-style extension, defined in PowerPC Cell and later VMX. The Xbox 360 Xenon supports them (decoder + xenia entry confirm).
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- **Implementation in xenia.** The shared snapshot calls `vmx::load_vector_left(mem, ea)`, which performs the unaligned partial-byte read and zero-fills the right side.
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- **VMX128 sibling (`lvlx128`).** Same semantics; different operand encoding (7-bit register field, addressing `v0..v127`).
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- **`lvlxl` is the LRU-hint variant.** Same data behaviour, hint ignored under emulation.
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## Related Instructions
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- [`lvrx`](lvrx.md), [`lvrx128`](lvrx.md) — load-right partner; combine to read unaligned 16 bytes.
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- [`lvlxl`](lvlxl.md), [`lvlxl128`](lvlxl.md) — LRU-hint variants.
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- [`lvx`](lvx.md), [`lvx128`](lvx.md) — aligned load (the EA-masking sibling).
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- [`stvlx`](stvlx.md), [`stvrx`](stvrx.md) — symmetric unaligned stores.
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## IBM Reference
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- [AIX 7.3 — `lvlx` (Load Vector Left Indexed)](https://www.ibm.com/docs/en/aix/7.3.0?topic=set-lvlx-load-vector-left-indexed-instruction)
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- `PowerISA v2.07B Book I` "Vector Facility"; Microsoft Xbox 360 XDK for VMX128 details.
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