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>
124 lines
5.0 KiB
Markdown
124 lines
5.0 KiB
Markdown
# `addic` — Add Immediate Carrying
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> **Category:** [Integer ALU](../categories/alu.md) · **Form:** [D](../forms/D.md) · **Opcode:** `0x30000000`
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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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| `addic` | `addic` | — | Add Immediate Carrying |
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## Syntax
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```asm
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addic [RD], [RA], [SIMM]
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```
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## Encoding
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### `addic` — form `D`
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- **Opcode word:** `0x30000000`
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- **Primary opcode (bits 0–5):** `12`
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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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| `RA` | addic: read | Source GPR (`r0`–`r31`). |
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| `SIMM` | addic: read | 16-bit signed immediate. Sign-extended to 64 bits before use. |
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| `RD` | addic: write | Destination GPR. |
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| `CA` | addic: write | XER[CA] carry bit. Read by add-with-carry/subtract-with-borrow instructions, written by carrying instructions. |
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## Register Effects
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### `addic`
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- **Reads (always):** `RA`, `SIMM`
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- **Reads (conditional):** _none_
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- **Writes (always):** `RD`, `CA`
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- **Writes (conditional):** _none_
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## Status-Register Effects
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- `addic`: **XER[CA]** ← carry-out of the add / borrow-in of the subtract (always).
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## Operation (pseudocode)
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```
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RT <- (RA) + EXTS(SIMM)
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CA <- carry_out
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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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**`addic`**
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- xenia-canary XML: [`tools/ppc-instructions.xml` — search for `mnem="addic"`](../../xenia-canary/tools/ppc-instructions.xml)
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- xenia-canary emit: [`src/xenia/cpu/ppc/ppc_emit_alu.cc:117`](../../xenia-canary/src/xenia/cpu/ppc/ppc_emit_alu.cc#L117)
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- xenia-rs opcode: [`crates/xenia-cpu/src/opcode.rs:8`](../../xenia-rs/crates/xenia-cpu/src/opcode.rs#L8)
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- xenia-rs decoder: [`crates/xenia-cpu/src/decoder.rs:336`](../../xenia-rs/crates/xenia-cpu/src/decoder.rs#L336)
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- xenia-rs interpreter: [`crates/xenia-cpu/src/interpreter.rs:135-144`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L135-L144)
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<details><summary>xenia-rs interpreter body (frozen snapshot)</summary>
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```rust
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PpcOpcode::addic => {
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// PPCBUG-002: 32-bit ABI. CA must be from a 32-bit unsigned compare;
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// canary's `AddDidCarry` truncates both operands to int32 first.
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let ra32 = ctx.gpr[instr.ra()] as u32;
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let imm32 = instr.simm16() as i32 as u32;
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let result32 = ra32.wrapping_add(imm32);
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ctx.xer_ca = if result32 < ra32 { 1 } else { 0 };
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ctx.gpr[instr.rd()] = result32 as u64;
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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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- **Immediate is sign-extended.** `SIMM` is a 16-bit signed value extended to 64 bits before the add. So `addic r3, r4, -1` adds `0xFFFFFFFFFFFFFFFF` to `r4` — it does not zero-extend.
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- **`XER[CA]` always written.** Unlike [`addi`](addi.md), this instruction exists to seed a multi-word add chain with an immediate. Carry-out is computed with the same `result < ra` unsigned-overflow check as [`addcx`](addcx.md).
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- **No `Rc` bit available.** This is the *non-record* form. For a record-form variant that also updates `CR0`, use [`addicx`](addicx.md) (`addic.`).
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- **No `OE` bit either.** `addic` cannot raise / observe signed overflow — only the carry. If you need `XER[OV]` you must use the XO-form [`addcx`](addcx.md) with `OE=1`.
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- **`RA = 0` reads register r0.** Unlike [`addi`](addi.md), `addic` does **not** treat the `RA` field of zero as a literal zero. The PowerISA gives this instruction the regular `RA` semantics, not `RA0`.
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- **Subtract immediate carrying via negation.** There is no `subic` mnemonic; assemblers synthesise `subic RT, RA, value` as `addic RT, RA, -value` (when `value` fits in 16 bits signed).
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## Related Instructions
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- [`addicx`](addicx.md) — same operation plus `Rc=1` CR0 update.
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- [`addi`](addi.md) — D-form add immediate without `XER[CA]`.
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- [`addis`](addis.md) — shifted form (immediate << 16).
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- [`addcx`](addcx.md) — XO-form: register operands, sets `XER[CA]`.
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- [`subfic`](subfic.md) — D-form: `RT ← SIMM − RA` with `XER[CA]`.
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## IBM Reference
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- [AIX 7.3 — `addic` (Add Immediate Carrying)](https://www.ibm.com/docs/en/aix/7.3.0?topic=set-addic-add-immediate-carrying-instruction)
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