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>
130 lines
5.2 KiB
Markdown
130 lines
5.2 KiB
Markdown
# `mcrf` — Move Condition Register Field
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> **Category:** [Control / CR / SPR](../categories/control.md) · **Form:** [XL](../forms/XL.md) · **Opcode:** `0x4c000000`
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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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| `mcrf` | `mcrf` | — | Move Condition Register Field |
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## Syntax
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```asm
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mcrf [CRFD], [CRFS]
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```
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## Encoding
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### `mcrf` — form `XL`
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- **Opcode word:** `0x4c000000`
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- **Primary opcode (bits 0–5):** `19`
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- **Extended opcode:** `0`
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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 (19) |
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| 6–10 | `BT/BO` | target / branch options |
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| 11–15 | `BA/BI` | source A / CR bit to test |
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| 16–20 | `BB` | source B |
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| 21–30 | `XO` | extended opcode (10 bits) |
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| 31 | `LK` | link flag |
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## Operands
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| Field | Role | Description |
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| --- | --- | --- |
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| `CRFS` | mcrf: read | CR source field. |
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| `CRFD` | mcrf: write | CR destination field (`crf`, 0–7). |
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## Register Effects
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### `mcrf`
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- **Reads (always):** `CRFS`
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- **Reads (conditional):** _none_
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- **Writes (always):** `CRFD`
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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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**`mcrf`**
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- xenia-canary XML: [`tools/ppc-instructions.xml` — search for `mnem="mcrf"`](../../xenia-canary/tools/ppc-instructions.xml)
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- xenia-canary emit: [`src/xenia/cpu/ppc/ppc_emit_control.cc:424`](../../xenia-canary/src/xenia/cpu/ppc/ppc_emit_control.cc#L424)
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- xenia-rs opcode: [`crates/xenia-cpu/src/opcode.rs:51`](../../xenia-rs/crates/xenia-cpu/src/opcode.rs#L51)
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- xenia-rs decoder: [`crates/xenia-cpu/src/decoder.rs:710`](../../xenia-rs/crates/xenia-cpu/src/decoder.rs#L710)
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- xenia-rs interpreter: [`crates/xenia-cpu/src/interpreter.rs:1683-1686`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L1683-L1686)
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<details><summary>xenia-rs interpreter body (frozen snapshot)</summary>
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```rust
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PpcOpcode::mcrf => {
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ctx.cr[instr.crfd()] = ctx.cr[instr.crfs()];
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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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- **Field-level (4-bit) move.** Unlike the bit-level CR-logical family ([`crand`](crand.md), …, [`crxor`](crxor.md)), `mcrf` copies *all four* bits of a CR field (LT, GT, EQ, SO) in one instruction. `CRFD` and `CRFS` are 3-bit field indices (0..7), each naming a 4-bit slice of the 32-bit CR.
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- **No source-field clobber.** The source field is read, not modified — `mcrf 0, 1` copies CR1 into CR0 leaving CR1 intact.
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- **Same-field is a NOP.** `mcrf cr0, cr0` reads-then-writes the same field; xenia's interpreter still does the assignment but the architectural state is unchanged.
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- **Use case.** Promote a non-default compare result into `cr0` so a default-`cr0` simplified branch (`beq label`) can consume it without spelling out `cr1`/`cr2`/etc. The alternative — `crmove` — would require four `cror` instructions to move all four bits.
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- **No CR0/XER side effects.** Pure CR-field dataflow.
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- **Not synchronising.** Reorderable.
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- **xenia exact match.** xenia-rs models the CR as an array of eight 4-bit fields, so `mcrf` is a single struct copy (`ctx.cr[crfd] = ctx.cr[crfs]`). Matches PowerISA semantics exactly.
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## Related Instructions
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- [`mfcr`](mfcr.md) — read the entire 32-bit CR into a GPR.
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- [`mtcrf`](mtcrf.md) — write selected CR fields from a GPR (uses an 8-bit field-mask).
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- [`mcrxr`](mcrxr.md) — copy `XER[SO..CA]` into a CR field and clear them.
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- [`mcrfs`](mcrfs.md) — copy an FPSCR field into a CR field.
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- [`crand`](crand.md), [`crandc`](crandc.md), [`creqv`](creqv.md), [`crnand`](crnand.md), [`crnor`](crnor.md), [`cror`](cror.md), [`crorc`](crorc.md), [`crxor`](crxor.md) — bit-level alternatives.
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- [`bcx`](../branch/bcx.md) — typical consumer.
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`mcrf` has no simplified mnemonics.
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## IBM Reference
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- [AIX 7.3 — `mcrf` (Move Condition Register Field)](https://www.ibm.com/docs/en/aix/7.3.0?topic=set-mcrf-move-condition-register-field-instruction)
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