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>
264 lines
11 KiB
Markdown
264 lines
11 KiB
Markdown
# `std` — Store Doubleword
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> **Category:** [Memory](../categories/memory.md) · **Form:** [DS](../forms/DS.md) · **Opcode:** `0xf8000000`
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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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| `std` | `std` | — | Store Doubleword |
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| `stdu` | `stdu` | — | Store Doubleword with Update |
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| `stdux` | `stdux` | — | Store Doubleword with Update Indexed |
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| `stdx` | `stdx` | — | Store Doubleword Indexed |
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## Syntax
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```asm
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std [RS], [ds]([RA0])
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stdu [RS], [ds]([RA])
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stdux [RS], [RA], [RB]
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stdx [RS], [RA0], [RB]
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```
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## Encoding
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### `std` — form `DS`
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- **Opcode word:** `0xf8000000`
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- **Primary opcode (bits 0–5):** `62`
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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) |
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| 11–15 | `RA` | source GPR (0 ⇒ literal 0) |
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| 16–29 | `DS` | 14-bit signed word-scaled displacement |
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| 30–31 | `XO` | extended opcode |
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### `stdu` — form `DS`
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- **Opcode word:** `0xf8000001`
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- **Primary opcode (bits 0–5):** `62`
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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) |
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| 11–15 | `RA` | source GPR (0 ⇒ literal 0) |
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| 16–29 | `DS` | 14-bit signed word-scaled displacement |
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| 30–31 | `XO` | extended opcode |
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### `stdux` — form `X`
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- **Opcode word:** `0x7c00016a`
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- **Primary opcode (bits 0–5):** `31`
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- **Extended opcode:** `181`
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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/FRT/VRT` | destination |
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| 11–15 | `RA/FRA/VRA` | source A |
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| 16–20 | `RB/FRB/VRB` | source B |
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| 21–30 | `XO` | extended opcode (10 bits) |
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| 31 | `Rc` | record-form flag |
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### `stdx` — form `X`
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- **Opcode word:** `0x7c00012a`
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- **Primary opcode (bits 0–5):** `31`
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- **Extended opcode:** `149`
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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/FRT/VRT` | destination |
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| 11–15 | `RA/FRA/VRA` | source A |
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| 16–20 | `RB/FRB/VRB` | source B |
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| 21–30 | `XO` | extended opcode (10 bits) |
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| 31 | `Rc` | record-form flag |
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## Operands
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| Field | Role | Description |
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| --- | --- | --- |
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| `RS` | std: read; stdu: read; stdux: read; stdx: read | Source GPR (alias for RD in some stores). |
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| `RA` | std: read; stdu: read; stdu: write; stdux: read; stdux: write | Source GPR (`r0`–`r31`). |
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| `ds` | std: read; stdu: read | 14-bit signed word-aligned displacement (`DS << 2`). |
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| `RB` | stdux: read; stdx: read | Source GPR. |
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| `RA0` | stdx: read | Source GPR; when the encoded register number is 0 the operand is the literal 64-bit zero, **not** `r0`. |
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## Register Effects
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### `std`
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- **Reads (always):** `RS`, `RA`, `ds`
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- **Reads (conditional):** _none_
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- **Writes (always):** _none_
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- **Writes (conditional):** _none_
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### `stdu`
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- **Reads (always):** `RS`, `RA`, `ds`
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- **Reads (conditional):** _none_
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- **Writes (always):** `RA`
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- **Writes (conditional):** _none_
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### `stdux`
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- **Reads (always):** `RS`, `RA`, `RB`
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- **Reads (conditional):** _none_
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- **Writes (always):** `RA`
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- **Writes (conditional):** _none_
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### `stdx`
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- **Reads (always):** `RS`, `RA0`, `RB`
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- **Reads (conditional):** _none_
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- **Writes (always):** _none_
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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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EA <- (RA|0) + EXTS(ds || 0b00)
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MEM(EA, 8) <- (RS)
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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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**`std`**
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- xenia-canary XML: [`tools/ppc-instructions.xml` — search for `mnem="std"`](../../xenia-canary/tools/ppc-instructions.xml)
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- xenia-canary emit: [`src/xenia/cpu/ppc/ppc_emit_memory.cc:575`](../../xenia-canary/src/xenia/cpu/ppc/ppc_emit_memory.cc#L575)
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- xenia-rs opcode: [`crates/xenia-cpu/src/opcode.rs:69`](../../xenia-rs/crates/xenia-cpu/src/opcode.rs#L69)
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- xenia-rs decoder: [`crates/xenia-cpu/src/decoder.rs:399`](../../xenia-rs/crates/xenia-cpu/src/decoder.rs#L399)
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- xenia-rs interpreter: [`crates/xenia-cpu/src/interpreter.rs:1399-1407`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L1399-L1407)
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<details><summary>xenia-rs interpreter body (frozen snapshot)</summary>
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```rust
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PpcOpcode::std => {
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let ea = if instr.ra() == 0 { 0u64 } else { ctx.gpr[instr.ra()] };
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let ea = ea.wrapping_add(instr.ds() as i64 as u64) as u32;
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if let Some(t) = ctx.reservation_table.as_ref().filter(|t| t.is_enabled()) {
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if t.has_active_reservers() { t.invalidate_for_write(ea); }
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}
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mem.write_u64(ea, ctx.gpr[instr.rs()]);
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ctx.pc += 4;
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}
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```
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</details>
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**`stdu`**
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- xenia-canary XML: [`tools/ppc-instructions.xml` — search for `mnem="stdu"`](../../xenia-canary/tools/ppc-instructions.xml)
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- xenia-canary emit: [`src/xenia/cpu/ppc/ppc_emit_memory.cc:594`](../../xenia-canary/src/xenia/cpu/ppc/ppc_emit_memory.cc#L594)
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- xenia-rs opcode: [`crates/xenia-cpu/src/opcode.rs:69`](../../xenia-rs/crates/xenia-cpu/src/opcode.rs#L69)
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- xenia-rs decoder: [`crates/xenia-cpu/src/decoder.rs:400`](../../xenia-rs/crates/xenia-cpu/src/decoder.rs#L400)
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- xenia-rs interpreter: [`crates/xenia-cpu/src/interpreter.rs:1417-1425`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L1417-L1425)
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<details><summary>xenia-rs interpreter body (frozen snapshot)</summary>
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```rust
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PpcOpcode::stdu => {
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let ea = ctx.gpr[instr.ra()].wrapping_add(instr.ds() as i64 as u64) as u32;
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if let Some(t) = ctx.reservation_table.as_ref().filter(|t| t.is_enabled()) {
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if t.has_active_reservers() { t.invalidate_for_write(ea); }
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}
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mem.write_u64(ea, ctx.gpr[instr.rs()]);
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ctx.gpr[instr.ra()] = ea 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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**`stdux`**
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- xenia-canary XML: [`tools/ppc-instructions.xml` — search for `mnem="stdux"`](../../xenia-canary/tools/ppc-instructions.xml)
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- xenia-canary emit: [`src/xenia/cpu/ppc/ppc_emit_memory.cc:604`](../../xenia-canary/src/xenia/cpu/ppc/ppc_emit_memory.cc#L604)
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- xenia-rs opcode: [`crates/xenia-cpu/src/opcode.rs:69`](../../xenia-rs/crates/xenia-cpu/src/opcode.rs#L69)
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- xenia-rs decoder: [`crates/xenia-cpu/src/decoder.rs:786`](../../xenia-rs/crates/xenia-cpu/src/decoder.rs#L786)
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- xenia-rs interpreter: [`crates/xenia-cpu/src/interpreter.rs:1426-1434`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L1426-L1434)
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<details><summary>xenia-rs interpreter body (frozen snapshot)</summary>
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```rust
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PpcOpcode::stdux => {
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let ea = ctx.gpr[instr.ra()].wrapping_add(ctx.gpr[instr.rb()]) as u32;
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if let Some(t) = ctx.reservation_table.as_ref().filter(|t| t.is_enabled()) {
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if t.has_active_reservers() { t.invalidate_for_write(ea); }
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}
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mem.write_u64(ea, ctx.gpr[instr.rs()]);
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ctx.gpr[instr.ra()] = ea 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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**`stdx`**
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- xenia-canary XML: [`tools/ppc-instructions.xml` — search for `mnem="stdx"`](../../xenia-canary/tools/ppc-instructions.xml)
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- xenia-canary emit: [`src/xenia/cpu/ppc/ppc_emit_memory.cc:614`](../../xenia-canary/src/xenia/cpu/ppc/ppc_emit_memory.cc#L614)
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- xenia-rs opcode: [`crates/xenia-cpu/src/opcode.rs:69`](../../xenia-rs/crates/xenia-cpu/src/opcode.rs#L69)
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- xenia-rs decoder: [`crates/xenia-cpu/src/decoder.rs:781`](../../xenia-rs/crates/xenia-cpu/src/decoder.rs#L781)
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- xenia-rs interpreter: [`crates/xenia-cpu/src/interpreter.rs:1408-1416`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L1408-L1416)
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<details><summary>xenia-rs interpreter body (frozen snapshot)</summary>
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```rust
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PpcOpcode::stdx => {
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let ea = if instr.ra() == 0 { 0u64 } else { ctx.gpr[instr.ra()] };
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let ea = ea.wrapping_add(ctx.gpr[instr.rb()]) as u32;
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if let Some(t) = ctx.reservation_table.as_ref().filter(|t| t.is_enabled()) {
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if t.has_active_reservers() { t.invalidate_for_write(ea); }
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}
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mem.write_u64(ea, ctx.gpr[instr.rs()]);
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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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- **DS-form, not D-form.** Like [`ld`](ld.md), `std` uses a 14-bit signed displacement scaled by 4 (`EXTS(ds || 0b00)`). Bits 30–31 are the extended opcode used to distinguish `std` (XO=0) from `stdu` (XO=1). Assemblers verify the byte displacement is a multiple of 4.
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- **Big-endian write.** The 64-bit value of `RS` is written most-significant-byte-first: `RS[0:7]` to `EA`, `RS[56:63]` to `EA+7`. Xenia's `mem.write_u64` performs the host-side byte swap if needed.
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- **`RA0` for `std` and `stdx`.** When `RA = 0`, base is the literal zero. Update forms `stdu` / `stdux` invoke `RA = 0` as an invalid form (no `RA = RS` collision possible — `RS` and `RA` are independent encoding fields, and even if equal the store reads `RS` first).
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- **Update-form post-write.** `stdu` / `stdux` write `EA` to `RA` after the store. Order is store-then-update.
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- **Alignment.** Xenon tolerates unaligned doubleword stores. PowerISA permits implementations to raise alignment exceptions; portable code keeps doublewords 8-byte aligned. Cache-inhibited storage may force alignment.
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- **Cache-line behaviour.** A doubleword store fits inside one Xenon cache line (128 B), so it's a single line write. A doubleword store that **straddles** a line boundary triggers two line accesses — keep doublewords 8-byte aligned to avoid the cost.
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- **64-bit pointer / counter stores.** Xbox 360 user code is 32-bit, but kernel structures, TOC entries, and 64-bit counters are stored with `std`.
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## Related Instructions
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- [`stw`](stw.md), [`sth`](sth.md), [`stb`](stb.md) — narrower integer stores.
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- [`stdbrx`](stdbrx.md) — byte-reversed doubleword store.
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- [`stdcx`](stdcx.md) — store-conditional (the doubleword reservation pair end).
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- [`ld`](ld.md), [`ldu`](ld.md), [`ldx`](ld.md), [`ldux`](ld.md) — corresponding loads.
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- [`stfd`](stfd.md) — FP doubleword store (same width, different register file).
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## IBM Reference
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- [AIX 7.3 — `std` (Store Doubleword)](https://www.ibm.com/docs/en/aix/7.3.0?topic=set-std-store-doubleword-instruction)
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- [AIX 7.3 — `stdu` / `stdx` / `stdux`](https://www.ibm.com/docs/en/aix/7.3.0?topic=set-stdu-store-doubleword-update-instruction)
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