10dc260f0c
CONSOLIDATION.md Phase 6. Both lived untracked in the project root -- on one
disk, backed up by nothing.
tools/ppc-manual/ 393 files, 3.7 MB. 455 instructions, 350 family pages,
598 mnemonics resolvable through index.json, plus the
generator that produced them.
tools/run-canary.sh the oracle launcher.
🔴 THE LAUNCHER WAS BROKEN IN TWO WAYS AND IS REWRITTEN, not copied:
* it pointed at `xenia-rs/sylpheed.iso`, a SYMLINK. Wine cannot resolve one
and says "path invalid", which reads as a corrupt image rather than a path
problem -- it has cost a session before. It now points at the real file and
warns if handed a symlink.
* it hardcoded one machine's absolute paths, and named `xenia-rs`, which this
consolidation retires. Now derived from the script's own location, with
SYLPH_CANARY_BIN / SYLPH_ISO overrides and a check that each exists.
The standing constraints are in its header where someone will read them: one
emulator at a time, Canary runs MUTED, and never judge a crash or a hang from
a Bash-launched run -- a SIGKILL that looked like the binary was the editor's
process supervisor.
⚠️ The manual's GENERATOR reads the xenia-rs source tree, which is going away.
Its decoder now lives here as crates/sylpheed-ppc, so the generator must be
repointed before it is run again. Recorded in the README rather than left for
someone to discover; the manual's content is checked in and regenerates from
nothing implicitly.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
4.7 KiB
4.7 KiB
vsrab — Vector Shift Right Algebraic Byte
Category: VMX (Altivec) · Form: VX · Opcode:
0x10000304
Assembler Mnemonics
| Mnemonic | XML entry | Flags | Description |
|---|---|---|---|
vsrab |
vsrab |
— | Vector Shift Right Algebraic Byte |
Syntax
vsrab [VD], [VA], [VB]
Encoding
vsrab — form VX
- Opcode word:
0x10000304 - Primary opcode (bits 0–5):
4 - Extended opcode:
772 - Synchronising: no
| Bits | Field | Meaning |
|---|---|---|
| 0–5 | OPCD |
primary opcode (4) |
| 6–10 | VRT/VD |
destination vector register |
| 11–15 | VRA/VA |
source A vector register |
| 16–20 | VRB/VB |
source B vector register |
| 21–31 | XO |
extended opcode (11 bits) |
Operands
| Field | Role | Description |
|---|---|---|
VA |
vsrab: read | Source A vector register. |
VB |
vsrab: read | Source B vector register. |
VD |
vsrab: write | Destination vector register. |
Register Effects
vsrab
- Reads (always):
VA,VB - 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 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
vsrab
- xenia-canary XML:
tools/ppc-instructions.xml— search formnem="vsrab" - xenia-canary emit:
src/xenia/cpu/ppc/ppc_emit_altivec.cc:1599 - xenia-rs opcode:
crates/xenia-cpu/src/opcode.rs:124 - xenia-rs decoder:
crates/xenia-cpu/src/decoder.rs:500 - xenia-rs interpreter:
crates/xenia-cpu/src/interpreter.rs:3868-3875
xenia-rs interpreter body (frozen snapshot)
PpcOpcode::vsrab => {
let a = crate::vmx::as_i8x16(ctx.vr[instr.ra()]);
let b = ctx.vr[instr.rb()].as_bytes();
let mut r = [0i8; 16];
for i in 0..16 { r[i] = a[i] >> (b[i] & 7); }
ctx.vr[instr.rd()] = crate::vmx::from_i8x16(r);
ctx.pc += 4;
}
Special Cases & Edge Conditions
- Per-lane arithmetic right-shift of signed bytes.
VD.b[i] = (int8)VA.b[i] >> (VB.b[i] & 7)— sign bit propagates into vacated high-order bits. Low 3 bits of each shift-count byte are honoured. - Per-lane shift counts. Splat via
vspltb/vspltisbfor uniform shifts. - Sign extension. Negative inputs produce values that stay negative (toward
-1), unlike logical shiftvsrbwhich zero-fills. - Big-endian byte lanes.
- No flags, no VSCR.
- No VMX128 sibling.
Related Instructions
vsrb— logical-right byte shift.vslb— byte logical-left.vrlb— byte rotate.vsrah,vsraw— arithmetic-right half-word / word.