CSEL

assembly

[
  "csel SrcP, SrcL, SrcR<.neg>, ->{t, u, Rd}"
]

block

[]

catalog_indices

[
  71
]

catalog_records

[
  {
    "asm": "csel SrcP, SrcL, SrcR<.neg>, ->{t, u, Rd}",
    "constraints": [],
    "encoding": [
      {
        "index": 0,
        "mask": "0x0000707f",
        "match": "0x00000077",
        "width_bits": 32
      }
    ],
    "encoding_kind": "L32",
    "fields": [
      {
        "name": "RegDst",
        "pieces": [
          {
            "instruction_lsb": 7,
            "value_lsb": 0,
            "width": 5
          }
        ],
        "signedness": "encoding-defined",
        "width": 5
      },
      {
        "name": "SrcL",
        "pieces": [
          {
            "instruction_lsb": 15,
            "value_lsb": 0,
            "width": 5
          }
        ],
        "signedness": "encoding-defined",
        "width": 5
      },
      {
        "name": "SrcP",
        "pieces": [
          {
            "instruction_lsb": 27,
            "value_lsb": 0,
            "width": 5
          }
        ],
        "signedness": "encoding-defined",
        "width": 5
      },
      {
        "name": "SrcR",
        "pieces": [
          {
            "instruction_lsb": 20,
            "value_lsb": 0,
            "width": 5
          }
        ],
        "signedness": "encoding-defined",
        "width": 5
      },
      {
        "name": "SrcRType",
        "pieces": [
          {
            "instruction_lsb": 25,
            "value_lsb": 0,
            "width": 2
          }
        ],
        "signedness": "encoding-defined",
        "width": 2
      }
    ],
    "form_id": "csel_32_ba77cbad3c99",
    "length_bits": 32,
    "mnemonic": "CSEL",
    "semantic_family": "ALU",
    "semantic_group": "ALU",
    "semantic_handler": "ScalarConditionalSelect",
    "semantic_summary": "CSEL snapshots three Reg5 sources, selects SrcL for a nonzero predicate or its optionally negated SrcR for zero, and publishes through the common scalar destination map.",
    "status": "accepted"
  }
]

classification

[
  "alu"
]

contract

{
  "block_composition": [
    "none"
  ],
  "canonical_assembly": [
    "csel SrcP, SrcL, SrcR<.neg>, ->{t, u, Rd}"
  ],
  "defaults": [
    "SrcP, SrcL, SrcR, SrcRType, and RegDst are required encoded fields; no field can be omitted.",
    "Assembly without .neg uses the canonical unmodified alias selected by the assembler. Raw SrcRType codes 00, 01, and 10 are assigned unmodified aliases; raw code 11 is .neg."
  ],
  "encoding_class": "standalone-encoded",
  "examples": [
    "csel a0, a1, a2, ->a3",
    "csel t#1, u#1, a0.neg, ->u",
    "csel zero, a0, a1, ->zero"
  ],
  "exceptions": [
    "An unavailable selected T/U queue source raises Fault_IllegalInstruction before the destination effect and before TPC advances, including a source not selected by the predicate outcome.",
    "CSEL raises no arithmetic, memory, alignment, permission, or control-flow exception."
  ],
  "field_contracts": {},
  "field_zero_meanings": {
    "RegDst": "Encoded zero discards the result.",
    "SrcL": "Encoded zero reads the architectural zero GPR.",
    "SrcP": "Encoded zero reads the architectural zero GPR and therefore selects the false value.",
    "SrcR": "Encoded zero reads the architectural zero GPR.",
    "SrcRType": "Encoded zero is an assigned unmodified false-source alias."
  },
  "legality": [
    "SrcP, SrcL, and SrcR codes 0..23 select absolute GPRs, 24..27 select T#1..T#4, and 28..31 select U#1..U#4 without consumption.",
    "All four SrcRType values are assigned. Codes 00, 01, and 10 leave SrcR unchanged; code 11 negates the complete XLEN value modulo 2^PTO_XLEN.",
    "RegDst codes 0 and 24..29 discard, codes 1..23 write GPRs, code 30 pushes U, and code 31 pushes T."
  ],
  "memory_effects": [
    "none"
  ],
  "operands": [
    {
      "field": "SrcP",
      "role": "Reg5 predicate source"
    },
    {
      "field": "SrcL",
      "role": "Reg5 true-value source"
    },
    {
      "field": "SrcR",
      "role": "Reg5 false-value source"
    },
    {
      "field": "SrcRType",
      "role": "CSEL-specific false-source modifier selector"
    },
    {
      "field": "RegDst",
      "role": "Reg5 destination or discard"
    }
  ],
  "ordering": [
    "Read all three Reg5 sources eagerly and non-consumingly before the destination write, even when the predicate outcome does not select one value.",
    "Publish the selected value, then advance TPC by four bytes."
  ],
  "standalone_opcode": true,
  "state_effects": [
    "Snapshot SrcP, SrcL, and SrcR before any destination effect. Only an all-zero SrcP is false; every nonzero bit pattern is true.",
    "For a true predicate publish the complete snapshotted SrcL. For a false predicate publish the complete snapshotted SrcR after the CSEL-specific raw modifier; negation wraps modulo 2^PTO_XLEN and does not fault.",
    "No memory, reservation, descriptor, numeric-status, block, privilege, branch-target, or other control state changes. Successful execution advances TPC by four bytes."
  ]
}

depends_on

[
  "PTO-BLOCK-MODEL-SCHEMA-PROFILE-ENCODING"
]

id

PTO-SCALAR-CSEL

mnemonic

CSEL

summary

CSEL snapshots three Reg5 sources, selects SrcL for a nonzero predicate or its optionally negated SrcR for zero, and publishes through the common scalar destination map.

surface

scalar

{
  "classification": [
    "alu"
  ],
  "documentation": "docs/scalar/alu/CSEL.md",
  "id": "PTO-SCALAR-CSEL",
  "instruction_contract": {
    "artifact": "spec/evidence/instruction-contract-closure.json",
    "mnemonic": "CSEL",
    "ndf_clause": "PTO-INST-SCALAR-CSEL"
  },
  "mnemonic": "CSEL",
  "readiness_subjects": [
    "ADR-0026",
    "ADR-0059"
  ],
  "semantic_tests": [
    "PTO-AVS-SCALAR-CSEL-ALIASES-001",
    "PTO-AVS-SCALAR-CSEL-MODIFIER-001",
    "PTO-AVS-SCALAR-CSEL-READINESS-001",
    "PTO-AVS-SCALAR-CSEL-SELECT-001"
  ],
  "source": "asl/scalar/alu/CSEL.asl",
  "surface": "scalar",
  "tests": [
    "PTO-AVS-SCALAR-CSEL-ALIASES-001",
    "PTO-AVS-SCALAR-CSEL-DECODE-001",
    "PTO-AVS-SCALAR-CSEL-MODIFIER-001",
    "PTO-AVS-SCALAR-CSEL-READINESS-001",
    "PTO-AVS-SCALAR-CSEL-SELECT-001"
  ]
}