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
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migration/project-root/ppc-manual/control/mtcrf.md
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migration/project-root/ppc-manual/control/mtcrf.md
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# `mtcrf` — Move to Condition Register Fields
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> **Category:** [Control / CR / SPR](../categories/control.md) · **Form:** [XFX](../forms/XFX.md) · **Opcode:** `0x7c000120`
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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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| `mtcrf` | `mtcrf` | — | Move to Condition Register Fields |
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## Syntax
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```asm
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mtcrf [CRM], [RS]
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```
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## Encoding
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### `mtcrf` — form `XFX`
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- **Opcode word:** `0x7c000120`
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- **Primary opcode (bits 0–5):** `31`
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- **Extended opcode:** `144`
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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 (31) |
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| 6–10 | `RT` | destination / source GPR |
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| 11–20 | `spr/tbr/FXM` | SPR/TBR number (byte-swapped halves) or CR field mask |
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| 21–30 | `XO` | extended opcode |
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| 31 | `—` | reserved |
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## Operands
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| Field | Role | Description |
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| --- | --- | --- |
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| `RS` | mtcrf: read | Source GPR (alias for RD in some stores). |
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| `CRM` | mtcrf: write | 8-bit CR field mask used by `mtcrf` — one bit per CR field. |
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## Register Effects
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### `mtcrf`
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- **Reads (always):** `RS`
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- **Reads (conditional):** _none_
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- **Writes (always):** `CRM`
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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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for i in 0..7:
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if CRM[i] then CR[i] <- (RS)[32+i*4 : 35+i*4]
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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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**`mtcrf`**
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- xenia-canary XML: [`tools/ppc-instructions.xml` — search for `mnem="mtcrf"`](../../xenia-canary/tools/ppc-instructions.xml)
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- xenia-canary emit: [`src/xenia/cpu/ppc/ppc_emit_control.cc:732`](../../xenia-canary/src/xenia/cpu/ppc/ppc_emit_control.cc#L732)
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- xenia-rs opcode: [`crates/xenia-cpu/src/opcode.rs:55`](../../xenia-rs/crates/xenia-cpu/src/opcode.rs#L55)
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- xenia-rs decoder: [`crates/xenia-cpu/src/decoder.rs:779`](../../xenia-rs/crates/xenia-cpu/src/decoder.rs#L779)
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- xenia-rs interpreter: [`crates/xenia-cpu/src/interpreter.rs:1631-1644`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L1631-L1644)
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<details><summary>xenia-rs interpreter body (frozen snapshot)</summary>
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```rust
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PpcOpcode::mtcrf => {
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let crm = instr.crm();
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let val = ctx.gpr[instr.rs()] as u32;
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let old = ctx.cr();
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let mut new = old;
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for i in 0..8u32 {
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if crm & (1 << (7 - i)) != 0 {
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let mask = 0xF << (28 - i * 4);
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new = (new & !mask) | (val & mask);
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}
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}
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ctx.set_cr(new);
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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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- **`CRM` is an 8-bit field-mask, MSB-first.** Each bit of `CRM` corresponds to one CR field: `CRM[0]` (mask bit `0x80`) selects CR0, `CRM[1]` (`0x40`) selects CR1, …, `CRM[7]` (`0x01`) selects CR7. Each *set* mask bit causes the corresponding 4-bit slice of `RS[32:63]` to overwrite that CR field; clear mask bits leave the field untouched.
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- **Slice positions inside `RS`.** Big-endian: bits 32..35 of `RS` map to CR0, bits 36..39 to CR1, …, bits 60..63 to CR7. The high 32 bits of `RS` are ignored.
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- **`mtcr RS` simplified mnemonic.** When `CRM = 0xFF`, all eight CR fields are written; assemblers fold this into `mtcr RS`. This is the dominant form (function epilogue restoring the saved CR).
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- **`mtocrf` variant.** PowerISA defines `mtocrf` as the single-field variant — encoded with the high bit of FXM set and exactly one CRM bit set. xenia-rs treats both as the same opcode and processes whatever `CRM` mask is present, so `mtocrf` works correctly without special handling.
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- **Use case in ABI.** Save/restore non-volatile CR fields (CR2, CR3, CR4 on the Xbox 360 ABI). The standard restore is `lwz r12, 8(r1); mtcrf 0x38, r12` — `0x38` = bits for CR2|CR3|CR4 — preserving the volatile fields the callee may have already updated.
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- **No CR0 / XER side effects.** `mtcrf` does not record into CR0; XER is untouched.
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- **xenia exact match.** xenia-rs decomposes the CR into a `u32`, applies a per-field mask, and reassembles via `set_cr`. The 8-bit `CRM` walk matches the spec exactly.
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- **Not synchronising.** Reorderable.
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## Related Instructions
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- [`mfcr`](mfcr.md) — read the entire CR into a GPR.
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- [`mcrf`](mcrf.md) — copy one CR field to another (no GPR involved).
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- [`mcrxr`](mcrxr.md), [`mcrfs`](mcrfs.md) — narrower CR-field moves from XER / FPSCR.
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- [`crand`](crand.md), [`cror`](cror.md), … — bit-level CR manipulation.
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### Simplified Mnemonics
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| Simplified | Expansion | Notes |
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| --- | --- | --- |
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| `mtcr RS` | `mtcrf 0xFF, RS` | write all eight CR fields from low half of RS |
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`mtocrf RS, FXM` is a related encoding handled by the same xenia-rs slot.
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## IBM Reference
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- [AIX 7.3 — `mtcrf` (Move to Condition Register Fields)](https://www.ibm.com/docs/en/aix/7.3.0?topic=set-mtcrf-move-condition-register-fields-instruction)
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- [AIX 7.3 — Condition register simplified mnemonics](https://www.ibm.com/docs/en/aix/7.3.0?topic=mnemonics-condition-register-logical-simplified)
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