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:
MechaCat02
149
migration/project-root/ppc-manual/fpu/fctiwx.md
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149
migration/project-root/ppc-manual/fpu/fctiwx.md
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# `fctiwx` — Floating Convert to Integer Word
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> **Category:** [Floating-Point](../categories/fpu.md) · **Form:** [X](../forms/X.md) · **Opcode:** `0xfc00001c`
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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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| `fctiw` | `fctiwx` | — | Floating Convert to Integer Word |
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| `fctiw.` | `fctiwx` | Rc=1 | Floating Convert to Integer Word |
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## Syntax
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```asm
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fctiw[Rc] [FD], [FB]
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```
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## Encoding
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### `fctiwx` — form `X`
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- **Opcode word:** `0xfc00001c`
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- **Primary opcode (bits 0–5):** `63`
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- **Extended opcode:** `14`
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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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## Operands
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| Field | Role | Description |
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| --- | --- | --- |
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| `FB` | fctiwx: read | Source B floating-point register. |
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| `FD` | fctiwx: write | Destination floating-point register. |
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| `CR` | fctiwx: 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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| `FPSCR` | fctiwx: write | Floating-Point Status and Control Register. |
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## Register Effects
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### `fctiwx`
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- **Reads (always):** `FB`
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- **Reads (conditional):** _none_
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- **Writes (always):** `FD`, `FPSCR`
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- **Writes (conditional):** `CR`
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## Status-Register Effects
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- `fctiwx`: **CR0** ← signed-compare(result, 0) with `SO ← XER[SO]`, when `Rc=1`.; **FPSCR** updated per IEEE-754 flags (FX, FEX, FPRF, FR, FI, exceptions).
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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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**`fctiwx`**
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- xenia-canary XML: [`tools/ppc-instructions.xml` — search for `mnem="fctiwx"`](../../xenia-canary/tools/ppc-instructions.xml)
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- xenia-canary emit: [`src/xenia/cpu/ppc/ppc_emit_fpu.cc:308`](../../xenia-canary/src/xenia/cpu/ppc/ppc_emit_fpu.cc#L308)
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- xenia-rs opcode: [`crates/xenia-cpu/src/opcode.rs:27`](../../xenia-rs/crates/xenia-cpu/src/opcode.rs#L27)
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- xenia-rs decoder: [`crates/xenia-cpu/src/decoder.rs:899`](../../xenia-rs/crates/xenia-cpu/src/decoder.rs#L899)
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- xenia-rs interpreter: [`crates/xenia-cpu/src/interpreter.rs:2928-2948`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L2928-L2948)
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<details><summary>xenia-rs interpreter body (frozen snapshot)</summary>
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```rust
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PpcOpcode::fctiwx => {
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// Convert to integer word (round per FPSCR[RN]).
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// PPCBUG-230: set XX on inexact.
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let val = ctx.fpr[instr.rb()];
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let result_u32: u32 = if val.is_nan() {
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fpscr::set_exception(ctx, fpscr::VXCVI | if fpscr::is_snan(val) { fpscr::VXSNAN } else { 0 });
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0x8000_0000
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} else if val > (i32::MAX as f64) {
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fpscr::set_exception(ctx, fpscr::VXCVI);
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0x7FFF_FFFF
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} else if val < (i32::MIN as f64) {
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fpscr::set_exception(ctx, fpscr::VXCVI);
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0x8000_0000
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} else {
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if val != val.trunc() { fpscr::set_exception(ctx, fpscr::XX); }
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fpscr::round_to_i32(ctx, val) as u32
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};
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ctx.fpr[instr.rd()] = f64::from_bits(result_u32 as u64);
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if instr.rc_bit() { update_cr1_from_fpscr(ctx); }
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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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- **binary64 → 32-bit signed integer, current rounding mode.** Result is rounded per `FPSCR[RN]` and packed into the low 32 bits of the destination FPR. The high 32 bits are architecturally undefined per PowerISA but xenia produces zero-extended `u32` (i.e. the high 32 bits are 0).
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- **Explicit saturation in xenia.** xenia's body clamps the rounded `f64` to `[i32::MIN as f64, i32::MAX as f64]` before the integer cast — this matches PPC's saturation behaviour for out-of-range positive/negative finite inputs.
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- **NaN sentinel.** xenia returns `0x0000_0000_8000_0000` for NaN inputs (i.e. `i32::MIN` in the low word). Matches PPC's `VXCVI` sentinel for NaN/out-of-range.
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- **Rounding implementation.** xenia uses `f64::round`, which rounds half-cases **away from zero** rather than to nearest-even. **xenia quirk:** values like `0.5`/`1.5`/`2.5` produce `1`/`2`/`3` under xenia vs `0`/`2`/`2` on PPC default rounding.
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- **`FPSCR[RN]` not honored.** xenia always uses `f64::round`, ignoring the rounding-mode field. **xenia quirk** for non-default modes.
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- **FPSCR side effects.** PPC: sets `XX`/`FX` on inexact, `VXCVI` on NaN/out-of-range. xenia does not update FPSCR.
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- **`Rc=1` (`fctiw.`)** copies `FPSCR[FX, FEX, VX, OX]` into CR1.
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- **Encoding.** X-form, primary 63, XO 14. Reads `FRB` only.
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- **Common pairing.** Followed by `stfiwx` to store the low-32-bit integer to memory (`stfd` would write the doubleword including the high bits, which on hardware are undefined).
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## Related Instructions
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- [`fctiwzx`](fctiwzx.md) — 32-bit integer with round-toward-zero (truncation).
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- [`fctidx`](fctidx.md), [`fctidzx`](fctidzx.md) — 64-bit integer variants.
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- [`fcfidx`](fcfidx.md) — inverse direction (i64 → f64); for i32 → f64, sign-extend then `fcfid`.
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- `stfiwx` — store low-32-bits FPR (the canonical companion to `fctiw`/`fctiwz`).
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- [`mffsx`](mffsx.md), [`mtfsfx`](mtfsfx.md) — control `FPSCR[RN]` (currently a no-op under xenia for this instruction).
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## IBM Reference
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- [AIX 7.3 — `fctiw` (Floating Convert to Integer Word)](https://www.ibm.com/docs/en/aix/7.3.0?topic=set-fctiw-floating-convert-integer-word-instruction)
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- [PowerISA v2.07B, Book I, Chapter 4 — Floating-Point Processor](https://openpowerfoundation.org/specifications/isa/) (high 32 bits are architecturally undefined; only `stfiwx` is the spec-blessed consumer).
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