LinxISA v0.57.1 Encoding Decisions

This page records the Linx projection of the normative PTO ISA 0.57.1 assignments. Encodings not named here remain defined by the canonical v0.57 opcode catalog and the locked PTO truth source.

Stability Rule

Established byte encodings, decode legality, and reserved behavior remain stable for every form not listed here. Legacy compatibility spellings are not revived; active sources accept only canonical v0.57 spellings.

TMA Function Window

All rows below use the TMA header pattern:

31..27=DataType, 26..25=00, 24..20=Function, 19..15=00010, 14..0 fixed block-split tail.

The mask excludes DataType and includes the function selector and fixed tail: mask=0x07ffffff.

Function	Alias	Match	Decision
0	BSTART.TLOAD	0x00011181	canonical
1	BSTART.TSTORE	0x00111181	canonical
2	BSTART.TMOV	0x00211181	canonical
3	BSTART.TPREFETCH	0x00311181	new v0.57 selector
4	BSTART.MGATHER	0x00411181	new v0.57 selector
5	BSTART.MSCATTER	0x00511181	new v0.57 selector
6	BSTART.MGATHER.MASK	0x00611181	new v0.57 selector
7	BSTART.MSCATTER.MASK	0x00711181	new v0.57 selector
8	BSTART.MGATHER.CAS	0x00811181	new v0.57 selector
9..31	reserved	—	illegal instruction

BSTART.TPREFETCH deliberately occupies the adjacent function slot after TLOAD, TSTORE, and TMOV. It is not allocated in a distant extension window.

TPREFETCH Encoding Contract

BSTART.TPREFETCH is encoded as TMA Function=3:

• mask: 0x07ffffff
• match: 0x00311181
• DataType remains the existing 5-bit TMA data-type field.

Architecturally, TPREFETCH is TLOAD without destinations. It uses the same address-generation and memory contract as TLOAD, but it must not allocate or write a tile destination.

PTO selector manifest rule

The exact 120-operation PTO map (98 TEPL, 9 TMA, and 13 CUBE) is the reviewed projection in:

isa/v0.57/state/pto_encoding_map.json

Its normative input is the commit and hashes frozen by isa/v0.57/pto-spec.lock.json; no workbook allocates an encoding. TEPL uses the raw two-bit Mode plus five-bit Function fields, so the logical selector is (Mode << 5) | Function. Exactly 98 of the 128 selector positions are accepted and the other 30 are reserved. The generator rejects any attempt to recover the retired 10-bit selector ABI.

CUBE Function Map

The PTO matrix rows use the inherited CUBE family plus named aliases:

Function	Canonical alias	PTO spelling
0	BSTART.TMATMUL	TMATMUL
1	BSTART.TMATMUL.BIAS	TMATMUL_BIAS
2	BSTART.TMATMUL.ACC	TMATMUL_ACC
4	BSTART.TMATMULMX	TMATMUL_MX
5	BSTART.TMATMULMX.BIAS	TMATMUL_MX_BIAS
6	BSTART.TMATMULMX.ACC	TMATMUL_MX_ACC
8	BSTART.ACCCVT	ACCCVT
16	BSTART.TGEMV	TGEMV
17	BSTART.TGEMV.BIAS	TGEMV_BIAS
18	BSTART.TGEMV.ACC	TGEMV_ACC
20	BSTART.TGEMVMX	TGEMV_MX
21	BSTART.TGEMVMX.BIAS	TGEMV_MX_BIAS
22	BSTART.TGEMVMX.ACC	TGEMV_MX_ACC

Only these 13 assigned named CUBE functions are legal. Every unassigned function is an illegal instruction; there is no generic executable BSTART.CUBE Function, DataType form. ACC is implicit architectural state and is never named by a B.IOT source or destination field.

Scalar Encoding Evidence

v0.57 adds the following 32-bit encodings from LinxISA/linx-isa#139 while leaving the existing 48-bit HL.CAS* forms unchanged:

Form	Mask	Match	v0.57 decision
CASB	0x0000707f	0x0000001b	32-bit local byte compare-and-swap
CASH	0x0000707f	0x0000101b	32-bit local halfword compare-and-swap
CASW	0x0000707f	0x0000201b	32-bit local word compare-and-swap
CASD	0x0000707f	0x0000301b	32-bit local doubleword compare-and-swap
DMA	0xfe007fff	0x0000700b	32-bit encoding of the inherited fixed 64-byte copy

For DMA, SrcL remains the source address and SrcR remains the destination address. PR #139 does not allocate a control-word format; its provisional “control parameters” wording is non-normative.

Rejection Rules

Assemblers, decoders, and tests must reject:

• generic mixed TMA source forms,
• unassigned TMA functions,
• all 30 reserved TEPL Mode/Function selectors,
• generic BSTART.CUBE and BSTART.FIXP,
• the retired B.ARG Tile descriptor carrier,
• TFMA, TFMOD, TFMODS, TADDC, TSUBC, TADDSC, TSUBSC, TLRELU, and TRANDOM,
• retired compatibility spellings from pre-v0.57 sources,
• PTO operations not present in the frozen 0.57.1 manifest.