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>
117 lines
4.9 KiB
Markdown
117 lines
4.9 KiB
Markdown
# `addi` — Add Immediate
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> **Category:** [Integer ALU](../categories/alu.md) · **Form:** [D](../forms/D.md) · **Opcode:** `0x38000000`
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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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| `addi` | `addi` | — | Add Immediate |
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## Syntax
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```asm
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addi [RD], [RA0], [SIMM]
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```
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## Encoding
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### `addi` — form `D`
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- **Opcode word:** `0x38000000`
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- **Primary opcode (bits 0–5):** `14`
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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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| `RA0` | addi: read | Source GPR; when the encoded register number is 0 the operand is the literal 64-bit zero, **not** `r0`. |
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| `SIMM` | addi: read | 16-bit signed immediate. Sign-extended to 64 bits before use. |
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| `RD` | addi: write | Destination GPR. |
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## Register Effects
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### `addi`
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- **Reads (always):** `RA0`, `SIMM`
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- **Reads (conditional):** _none_
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- **Writes (always):** `RD`
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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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if RA = 0 then RT <- EXTS(SIMM)
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else RT <- (RA) + EXTS(SIMM)
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```
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## C Translation Example
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```c
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/* addi RT, RA, SIMM — RA=0 means literal 0 */
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uint64_t base = (insn.RA == 0) ? 0 : r[insn.RA];
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r[insn.RT] = base + (uint64_t)(int64_t)(int16_t)insn.SIMM;
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```
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## Implementation References
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**`addi`**
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- xenia-canary XML: [`tools/ppc-instructions.xml` — search for `mnem="addi"`](../../xenia-canary/tools/ppc-instructions.xml)
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- xenia-canary emit: [`src/xenia/cpu/ppc/ppc_emit_alu.cc:103`](../../xenia-canary/src/xenia/cpu/ppc/ppc_emit_alu.cc#L103)
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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:338`](../../xenia-rs/crates/xenia-cpu/src/decoder.rs#L338)
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- xenia-rs interpreter: [`crates/xenia-cpu/src/interpreter.rs:114-120`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L114-L120)
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<details><summary>xenia-rs interpreter body (frozen snapshot)</summary>
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```rust
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PpcOpcode::addi => {
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// PPCBUG-001: 32-bit ABI. `li rT, -1` (= addi rT, r0, -1) must produce
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// 0x00000000_FFFFFFFF, not 0xFFFFFFFF_FFFFFFFF (sign-extended simm16).
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let ra_val = if instr.ra() == 0 { 0 } else { ctx.gpr[instr.ra()] };
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ctx.gpr[instr.rd()] = ra_val.wrapping_add(instr.simm16() as i64 as u64) as u32 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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- **`RA0` semantics.** When the encoded `RA` field is `0` the operand is the literal constant `0`, **not** the value of `r0`. This lets `addi rT, 0, SIMM` load a constant (the `li rT, SIMM` simplified mnemonic). To use `r0`'s value you must use a register-register add (`add RT, r0, RB` through a temp) or an instruction without `RA0` semantics.
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- **No flags written.** Unlike `add`, `addi` cannot be `Rc` or `OE` — no CR or XER update. Use [`addic`](addic.md) if you need `XER[CA]`, or [`addicx`](addicx.md) (`addic.`) if you need both `XER[CA]` and a CR0 update.
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- **Immediate is 16-bit signed** (`SIMM`, range `−32768 … +32767`), sign-extended to 64 bits before the add. No carry/overflow is produced regardless of the result.
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- **Simplified mnemonics.** Assemblers recognise several aliases that all assemble to `addi`:
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- `li RT, SIMM` ≡ `addi RT, 0, SIMM` (load immediate; relies on `RA0`).
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- `la RT, D(RA)` ≡ `addi RT, RA, D` (load address; purely syntactic).
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- `subi RT, RA, SIMM` ≡ `addi RT, RA, −SIMM`.
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- **PC-relative idiom.** `addi RT, RA, D` is the low-half completion of a two-instruction address load preceded by [`addis`](addis.md) `RT, 0, HI`. The assembler emits `@ha`/`@l` relocations so the low half can be negative without corrupting the high half (add-compensation).
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## Related Instructions
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- [`addis`](addis.md) — same encoding family but the immediate is shifted left by 16 bits. Together they build any 32-bit constant or PC-relative address.
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- [`addic`](addic.md), [`addicx`](addicx.md) — D-form adds that **do** set `XER[CA]` (and CR0 for the record form).
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- [`addx`](addx.md) — the register-register form.
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- [`subfic`](subfic.md) — reverse-subtract immediate (`imm − RA`) with carry.
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- [`ori`](ori.md), [`oris`](oris.md) — the alternative D-form constant-building instructions (but these don't add, they OR).
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## IBM Reference
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- [AIX 7.3 — `addi` (Add Immediate)](https://www.ibm.com/docs/en/aix/7.3.0?topic=set-addi-add-immediate-instruction)
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- [AIX 7.3 — `li` (Load Immediate, simplified mnemonic)](https://www.ibm.com/docs/en/aix/7.3.0?topic=mnemonics-li-load-immediate)
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