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chore: add migration/ bundle for cross-machine setup

Browse Source 
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:
MechaCat02
2026-05-10 21:38:38 +02:00
parent 8e709b0a24
commit e6d43a23ac
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# `vctsxs` — Vector Convert to Signed Fixed-Point Word Saturate
> **Category:** [VMX (Altivec)](../categories/vmx.md) · **Form:** [VX](../forms/VX.md) · **Opcode:** `0x100003ca`
<!-- GENERATED: BEGIN -->
## Assembler Mnemonics
| Mnemonic | XML entry | Flags | Description |
| --- | --- | --- | --- |
| `vctsxs` | `vctsxs` | — | Vector Convert to Signed Fixed-Point Word Saturate |
## Syntax
```asm
vctsxs [VD], [VB], [UIMM]
```
## Encoding
### `vctsxs` — form `VX`
- **Opcode word:** `0x100003ca`
- **Primary opcode (bits 0–5):** `4`
- **Extended opcode:** `970`
- **Synchronising:** no
| Bits | Field | Meaning |
| --- | --- | --- |
| 0–5 | `OPCD` | primary opcode (4) |
| 6–10 | `VRT/VD` | destination vector register |
| 11–15 | `VRA/VA` | source A vector register |
| 16–20 | `VRB/VB` | source B vector register |
| 21–31 | `XO` | extended opcode (11 bits) |
## Operands
| Field | Role | Description |
| --- | --- | --- |
| `VB` | vctsxs: read | Source B vector register. |
| `UIMM` | vctsxs: read | 16-bit unsigned immediate. Zero-extended. |
| `VD` | vctsxs: write | Destination vector register. |
| `VSCR` | vctsxs: write | Vector Status and Control Register (NJ/SAT bits). |
## Register Effects
### `vctsxs`
- **Reads (always):** `VB`, `UIMM`
- **Reads (conditional):** _none_
- **Writes (always):** `VD`, `VSCR`
- **Writes (conditional):** _none_
## Status-Register Effects
- `vctsxs`: **VSCR[SAT]** may be stickied on saturating vector operations.
## Operation (pseudocode)
```
; Pseudocode derives directly from the xenia-rs interpreter
; arm (see Implementation References). Operation semantics:
; - Read source operands from the fields listed under Operands.
; - Apply the arithmetic / logical / memory action described
; in the Description field above.
; - Write results to the destination register(s); update any
; status bits enumerated under Status-Register Effects.
; Consult the IBM AIX reference link under IBM Reference for
; canonical PPC-style pseudocode where xenia's expression is
; terse.
```
## C Translation Example
```c
/* C translation: the xenia-rs interpreter arm below in */
/* Implementation References is the authoritative semantic */
/* snapshot. Translate it line-by-line: */
/* - ctx.gpr[N] -> r[N] (or f[]/v[] for FPRs/VRs) */
/* - mem.read_u*/write_u* -> mem_read_u*_be / mem_write_u*_be */
/* - ctx.update_cr_signed(fld, v) -> update_cr_signed(fld, v) */
/* - ctx.xer_ca / xer_ov / xer_so -> xer.CA / xer.OV / xer.SO */
/* The Register Effects and Status-Register Effects tables above */
/* enumerate every side effect a faithful translation must emit. */
```
## Implementation References
**`vctsxs`**
- xenia-canary XML: [`tools/ppc-instructions.xml` — search for `mnem="vctsxs"`](../../xenia-canary/tools/ppc-instructions.xml)
- xenia-canary emit: [`src/xenia/cpu/ppc/ppc_emit_altivec.cc:536`](../../xenia-canary/src/xenia/cpu/ppc/ppc_emit_altivec.cc#L536)
- xenia-rs opcode: [`crates/xenia-cpu/src/opcode.rs:98`](../../xenia-rs/crates/xenia-cpu/src/opcode.rs#L98)
- xenia-rs decoder: [`crates/xenia-cpu/src/decoder.rs:517`](../../xenia-rs/crates/xenia-cpu/src/decoder.rs#L517)
- xenia-rs interpreter: [`crates/xenia-cpu/src/interpreter.rs:4281-4292`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L4281-L4292)
<details><summary>xenia-rs interpreter body (frozen snapshot)</summary>
```rust
PpcOpcode::vctsxs => {
let uimm = (instr.raw >> 16) & 0x1F;
let b = ctx.vr[instr.rb()].as_f32x4();
let mut r = [0i32; 4]; let mut sat = false;
for i in 0..4 {
let (v, s) = crate::vmx::cvt_f32_to_i32_sat(b[i], uimm);
r[i] = v; sat |= s;
}
if sat { ctx.set_vscr_sat(true); }
ctx.vr[instr.rd()] = crate::vmx::from_i32x4(r);
ctx.pc += 4;
}
```
</details>
<!-- GENERATED: END -->
## Special Cases & Edge Conditions
- **Convert IEEE float lane to signed-Q `int32`, saturating.** For each of the four word lanes, `VD[i] = clamp(round_toward_zero(VB[i] * 2^UIMM), INT32_MIN, INT32_MAX)`. The 5-bit `UIMM` (bits 11..15) gives the Q-format fractional shift, in `0..31`.
- **Saturating, not wrapping.** Out-of-range floats clamp to `INT32_MIN` (negative overflow) or `INT32_MAX` (positive overflow) — *not* the wrap-around behaviour of x86 `cvttps2dq` (which produces `0x80000000` on overflow regardless of sign). Xenia's `crate::vmx::cvt_f32_to_i32_sat` ([`crates/xenia-cpu/src/vmx.rs`](../../xenia-rs/crates/xenia-cpu/src/vmx.rs)) handles the difference.
- **NaN → 0.** A NaN input becomes `0` in the output lane and stickies `VSCR[SAT]`. (Many references state "NaN → INT32_MIN"; verify against [`vmx.rs`](../../xenia-rs/crates/xenia-cpu/src/vmx.rs) for the canonical xenia behaviour, which differs from POWER ISA wording.)
- **`VSCR[SAT]` is sticky-set** if any lane saturates (overflow or NaN). Cleared only by [`mtvscr`](mtvscr.md).
- **Rounding is truncate-toward-zero.** Always; no per-instruction rounding control.
- **`VSCR[NJ]` flushes denormal *inputs* to zero before scaling** (Xenon default).
- **Big-endian word lanes.** Lane 0 is the most-significant word.
- **No XER changes, no traps.**
- **No VMX128 sibling.**
- **Inverse of [`vcfsx`](vcfsx.md)**, but the inverse direction saturates rather than wraps — round-trips lose the magnitude of out-of-range values.
## Related Instructions
- [`vctuxs`](vctuxs.md) — same shape, unsigned destination.
- [`vcfsx`](vcfsx.md), [`vcfux`](vcfux.md) — inverse direction (int → float with Q-shift).
- [`vrfin`](vrfin.md), [`vrfip`](vrfip.md), [`vrfim`](vrfim.md), [`vrfiz`](vrfiz.md) — float-to-float rounding modes (round-to-nearest, up, down, toward-zero) when staying in float.
- [`mtvscr`](mtvscr.md) / [`mfvscr`](mfvscr.md) — read or clear `VSCR[SAT]`.
## IBM Reference
- [AIX 7.3 — `vctsxs` (Vector Convert to Signed Fixed-Point Word Saturate)](https://www.ibm.com/docs/en/aix/7.3.0?topic=set-vctsxs-vector-convert-signed-fixed-point-word-saturate-instruction)
- [IBM AltiVec Technology Programmer's Interface Manual, Chapter 5 — Conversion Instructions](https://www.nxp.com/docs/en/reference-manual/ALTIVECPIM.pdf)