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>
128 lines
5.5 KiB
Markdown
128 lines
5.5 KiB
Markdown
# `andis.` — AND Immediate Shifted
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> **Category:** [Integer ALU](../categories/alu.md) · **Form:** [D](../forms/D.md) · **Opcode:** `0x74000000`
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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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| `andis.` | `andis.` | — | AND Immediate Shifted |
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## Syntax
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```asm
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andis. [RA], [RS], [UIMM]
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```
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## Encoding
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### `andis.` — form `D`
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- **Opcode word:** `0x74000000`
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- **Primary opcode (bits 0–5):** `29`
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- **Extended opcode:** —
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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` | destination GPR (or RS when storing) |
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| 11–15 | `RA` | source GPR (0 ⇒ literal 0 for RA0 forms) |
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| 16–31 | `D/SI/UI` | 16-bit signed or unsigned immediate |
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## Operands
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| Field | Role | Description |
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| --- | --- | --- |
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| `RS` | andis.: read | Source GPR (alias for RD in some stores). |
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| `UIMM` | andis.: read | 16-bit unsigned immediate. Zero-extended. |
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| `RA` | andis.: write | Source GPR (`r0`–`r31`). |
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| `CR` | andis.: write | 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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## Register Effects
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### `andis.`
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- **Reads (always):** `RS`, `UIMM`
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- **Reads (conditional):** _none_
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- **Writes (always):** `RA`, `CR`
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- **Writes (conditional):** _none_
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## Status-Register Effects
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- `andis.`: **CR0** ← signed-compare(result, 0) with `SO ← XER[SO]` (always).
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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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**`andis.`**
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- xenia-canary XML: [`tools/ppc-instructions.xml` — search for `mnem="andis."`](../../xenia-canary/tools/ppc-instructions.xml)
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- xenia-canary emit: [`src/xenia/cpu/ppc/ppc_emit_alu.cc:665`](../../xenia-canary/src/xenia/cpu/ppc/ppc_emit_alu.cc#L665)
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- xenia-rs opcode: [`crates/xenia-cpu/src/opcode.rs:9`](../../xenia-rs/crates/xenia-cpu/src/opcode.rs#L9)
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- xenia-rs decoder: [`crates/xenia-cpu/src/decoder.rs:352`](../../xenia-rs/crates/xenia-cpu/src/decoder.rs#L352)
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- xenia-rs interpreter: [`crates/xenia-cpu/src/interpreter.rs:505-511`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L505-L511)
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<details><summary>xenia-rs interpreter body (frozen snapshot)</summary>
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```rust
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PpcOpcode::andisx => {
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// PPCBUG-023: 32-bit ABI CR0 view. `andis. rA, rS, 0x8000` to test
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// sign bit of a 32-bit word now correctly classifies bit 31 = 1 as LT.
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ctx.gpr[instr.ra()] = ctx.gpr[instr.rs()] & ((instr.uimm16() as u64) << 16);
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ctx.update_cr_signed(0, ctx.gpr[instr.ra()] as u32 as i32 as i64);
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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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- **Always `Rc=1`.** Like [`andix`](andix.md), the dot is part of the mnemonic; no plain `andis` exists.
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- **Immediate is shifted left 16, zero-extended.** Effective mask is `(UIMM << 16) & 0xFFFFFFFF`, so the only bits that can survive in `RA` are bits 32–47 (in PowerISA bit numbering, equivalent to bits 16–31 of the low 32 bits) of `RS`. Bits 0–31 and bits 48–63 of `RA` are forced to zero.
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- **Together with `andi.` covers the entire low 32 bits.** Any 32-bit mask can be applied with `andis. + andi.` (two instructions). Larger masks need `rlwinm` or a constructed register operand to [`andx`](andx.md).
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- **High 32 bits of result are always zero.** Because the immediate is at bits 32–47, no information from `RS[0:31]` survives. Useful as a quick "extract bits 32–47, zero the rest" primitive.
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- **CR0 update is unconditional** and uses the standard signed-compare-to-zero semantics with `XER[SO]` folded into `SO`.
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- **64-bit CR update on Xenon, 32-bit in xenia-rs.** The `result as i32 as i64` truncation in [`interpreter.rs:326`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L326) is harmless: the result is bounded by `0x00000000_FFFF0000`, which fits the 32-bit window exactly.
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## Related Instructions
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- [`andix`](andix.md) — companion (immediate not shifted).
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- [`andx`](andx.md), [`andcx`](andcx.md) — register AND.
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- [`oris`](oris.md), [`xoris`](xoris.md) — sister immediate-shifted logicals.
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- [`rlwinmx`](rlwinmx.md) — full mask-and-rotate when the bits of interest aren't aligned to a 16-bit boundary.
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## IBM Reference
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- [AIX 7.3 — `andis.` (AND Immediate Shifted)](https://www.ibm.com/docs/en/aix/7.3.0?topic=set-andis-immediate-shifted-instruction)
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