# `lvrxl` — Load Vector Right Indexed LRU > **Category:** [Memory](../categories/memory.md) · **Form:** [X](../forms/X.md) · **Opcode:** `0x7c00064e` ## Assembler Mnemonics | Mnemonic | XML entry | Flags | Description | | --- | --- | --- | --- | | `lvrxl` | `lvrxl` | — | Load Vector Right Indexed LRU | | `lvrxl128` | `lvrxl128` | — | Load Vector Right Indexed LRU 128 | ## Syntax ```asm lvrxl [VD], [RA0], [RB] lvrxl128 [VD], [RA0], [RB] ``` ## Encoding ### `lvrxl` — form `X` - **Opcode word:** `0x7c00064e` - **Primary opcode (bits 0–5):** `31` - **Extended opcode:** `807` - **Synchronising:** no | Bits | Field | Meaning | | --- | --- | --- | | 0–5 | `OPCD` | primary opcode | | 6–10 | `RT/FRT/VRT` | destination | | 11–15 | `RA/FRA/VRA` | source A | | 16–20 | `RB/FRB/VRB` | source B | | 21–30 | `XO` | extended opcode (10 bits) | | 31 | `Rc` | record-form flag | ### `lvrxl128` — form `VX128_1` - **Opcode word:** `0x10000643` - **Primary opcode (bits 0–5):** `4` - **Extended opcode:** `1603` - **Synchronising:** no | Bits | Field | Meaning | | --- | --- | --- | | 0–5 | `OPCD` | primary opcode (4) | | 6–10 | `VD128l` | destination low 5 bits | | 11–15 | `RA` | address register | | 16–20 | `RB` | offset register | | 21–27 | `XO` | extended opcode | | 28–29 | `VD128h` | destination high 2 bits | | 30–31 | `—` | reserved | ## Operands | Field | Role | Description | | --- | --- | --- | | `RA0` | lvrxl: read; lvrxl128: read | Source GPR; when the encoded register number is 0 the operand is the literal 64-bit zero, **not** `r0`. | | `RB` | lvrxl: read; lvrxl128: read | Source GPR. | | `VD` | lvrxl: write; lvrxl128: write | Destination vector register. | ## Register Effects ### `lvrxl` - **Reads (always):** `RA0`, `RB` - **Reads (conditional):** _none_ - **Writes (always):** `VD` - **Writes (conditional):** _none_ ### `lvrxl128` - **Reads (always):** `RA0`, `RB` - **Reads (conditional):** _none_ - **Writes (always):** `VD` - **Writes (conditional):** _none_ ## Status-Register Effects _No condition-register or status-register effects._ ## Operation (pseudocode) ``` ; Pseudocode derives directly from the xenia-rs interpreter ; arm (see Implementation References). Operation semantics: ; - Read source operands from the fields listed under Operands. ; - Apply the arithmetic / logical / memory action described ; in the Description field above. ; - Write results to the destination register(s); update any ; status bits enumerated under Status-Register Effects. ; Consult the IBM AIX reference link under IBM Reference for ; canonical PPC-style pseudocode where xenia's expression is ; terse. ``` ## C Translation Example ```c /* C translation: the xenia-rs interpreter arm below in */ /* Implementation References is the authoritative semantic */ /* snapshot. Translate it line-by-line: */ /* - ctx.gpr[N] -> r[N] (or f[]/v[] for FPRs/VRs) */ /* - mem.read_u*/write_u* -> mem_read_u*_be / mem_write_u*_be */ /* - ctx.update_cr_signed(fld, v) -> update_cr_signed(fld, v) */ /* - ctx.xer_ca / xer_ov / xer_so -> xer.CA / xer.OV / xer.SO */ /* The Register Effects and Status-Register Effects tables above */ /* enumerate every side effect a faithful translation must emit. */ ``` ## Implementation References **`lvrxl`** - xenia-canary XML: [`tools/ppc-instructions.xml` — search for `mnem="lvrxl"`](../../xenia-canary/tools/ppc-instructions.xml) - xenia-canary emit: [`src/xenia/cpu/ppc/ppc_emit_altivec.cc:247`](../../xenia-canary/src/xenia/cpu/ppc/ppc_emit_altivec.cc#L247) - xenia-rs opcode: [`crates/xenia-cpu/src/opcode.rs:45`](../../xenia-rs/crates/xenia-cpu/src/opcode.rs#L45) - xenia-rs decoder: [`crates/xenia-cpu/src/decoder.rs:842`](../../xenia-rs/crates/xenia-cpu/src/decoder.rs#L842) - xenia-rs interpreter: [`crates/xenia-cpu/src/interpreter.rs:3093-3097`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L3093-L3097)
xenia-rs interpreter body (frozen snapshot) ```rust PpcOpcode::lvrx | PpcOpcode::lvrxl => { let ea = ea_indexed(ctx, instr); ctx.vr[instr.rd()] = crate::vmx::load_vector_right(mem, ea); ctx.pc += 4; } ```
**`lvrxl128`** - xenia-canary XML: [`tools/ppc-instructions.xml` — search for `mnem="lvrxl128"`](../../xenia-canary/tools/ppc-instructions.xml) - xenia-canary emit: [`src/xenia/cpu/ppc/ppc_emit_altivec.cc:250`](../../xenia-canary/src/xenia/cpu/ppc/ppc_emit_altivec.cc#L250) - xenia-rs opcode: [`crates/xenia-cpu/src/opcode.rs:45`](../../xenia-rs/crates/xenia-cpu/src/opcode.rs#L45) - xenia-rs decoder: [`crates/xenia-cpu/src/decoder.rs:425`](../../xenia-rs/crates/xenia-cpu/src/decoder.rs#L425) - xenia-rs interpreter: [`crates/xenia-cpu/src/interpreter.rs:3098-3102`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L3098-L3102)
xenia-rs interpreter body (frozen snapshot) ```rust PpcOpcode::lvrx128 | PpcOpcode::lvrxl128 => { let ea = ea_indexed(ctx, instr); ctx.vr[instr.vd128()] = crate::vmx::load_vector_right(mem, ea); ctx.pc += 4; } ```
## Special Cases & Edge Conditions - **Same data effect as [`lvrx`](lvrx.md), with LRU cache hint.** Reads `(EA mod 16)` bytes from the previous aligned line into the right half of `VD`; left half zero-filled. The `l` suffix tells the cache the line is least-recently-used. - **Hint ignored under emulation.** Xenia's snapshot is shared with `lvrx` (`PpcOpcode::lvrx | PpcOpcode::lvrxl => …`). - **No alignment masking.** The exact `EA` controls how data shifts. - **`RA0` semantics.** `RA = 0` selects literal zero. - **Microsoft Xbox 360 specific.** Part of the VMX128 / Cell BE extended set. - **Streaming-read use case.** Pair with [`lvlxl`](lvlxl.md) when iterating across a buffer that will not be revisited; the LRU hint frees cache capacity for the next line. - **VMX128 sibling (`lvrxl128`).** Identical semantics; alternative operand encoding addressing `v0..v127`. ## Related Instructions - [`lvrx`](lvrx.md), [`lvrx128`](lvrx.md) — non-hint variants. - [`lvlxl`](lvlxl.md), [`lvlxl128`](lvlxl.md) — load-left LRU partner. - [`lvxl`](lvxl.md), [`lvxl128`](lvxl.md) — aligned LRU vector load. - [`stvrxl`](stvrxl.md), [`stvlxl`](stvlxl.md) — symmetric LRU stores. ## IBM Reference - [AIX 7.3 — `lvrxl` (Load Vector Right Indexed Last)](https://www.ibm.com/docs/en/aix/7.3.0?topic=reference-instruction-set) - `PowerISA v2.07B Book I` "Vector Facility"; Microsoft Xbox 360 XDK for VMX128 cache-hint behaviour.