BSTART

assembly

[
  "BSTART DIRECT, <label>",
  "BSTART COND, <label>"
]

block

[]

catalog_indices

[
  13,
  14
]

catalog_records

[
  {
    "asm": "BSTART DIRECT, <label>",
    "constraints": [],
    "encoding": [
      {
        "index": 0,
        "mask": "0x0000007f",
        "match": "0x00000011",
        "width_bits": 32
      }
    ],
    "encoding_kind": "L32",
    "fields": [
      {
        "name": "simm25",
        "pieces": [
          {
            "instruction_lsb": 7,
            "value_lsb": 0,
            "width": 25
          }
        ],
        "signedness": "signed",
        "width": 25
      }
    ],
    "form_id": "bstart_32_7eb93b649748",
    "length_bits": 32,
    "mnemonic": "BSTART",
    "semantic_family": "CMD",
    "semantic_group": "Bundle Split",
    "semantic_handler": "ExecuteBundleStart",
    "semantic_summary": "Initializes the single BARG continuation record after any retiring block commits successfully.",
    "status": "accepted"
  },
  {
    "asm": "BSTART COND, <label>",
    "constraints": [],
    "encoding": [
      {
        "index": 0,
        "mask": "0x0000007f",
        "match": "0x00000021",
        "width_bits": 32
      }
    ],
    "encoding_kind": "L32",
    "fields": [
      {
        "name": "simm25",
        "pieces": [
          {
            "instruction_lsb": 7,
            "value_lsb": 0,
            "width": 25
          }
        ],
        "signedness": "signed",
        "width": 25
      }
    ],
    "form_id": "bstart_32_e11e678a32ac",
    "length_bits": 32,
    "mnemonic": "BSTART",
    "semantic_family": "CMD",
    "semantic_group": "Bundle Split",
    "semantic_handler": "ExecuteBundleStart",
    "semantic_summary": "Initializes the single BARG continuation record after any retiring block commits successfully.",
    "status": "accepted"
  }
]

classification

[
  "lifecycle"
]

contract

{
  "block_composition": [
    "none"
  ],
  "canonical_assembly": [
    "BSTART DIRECT, <label>",
    "BSTART COND, <label>"
  ],
  "defaults": [
    "simm25 zero is a real zero displacement, so BARG.BPCN equals the BSTART address P."
  ],
  "encoding_class": "standalone-encoded",
  "examples": [
    "BSTART DIRECT, <label>"
  ],
  "exceptions": [
    "An odd computed BARG.BPCN raises Fault_InstructionPC before changing BARG.",
    "A failed retiring-block commit preserves the retiring BARG and does not install the candidate BARG."
  ],
  "field_contracts": {},
  "field_zero_meanings": {
    "simm25": "Encoded zero supplies a zero displacement or zero immediate value."
  },
  "legality": [
    "The low-seven-bit 0010001 form is DIRECT only; CALL is not an alias.",
    "The low-seven-bit 0100001 form is COND only."
  ],
  "memory_effects": [
    "Any memory effects of the retiring block complete before the new BARG is installed; BSTART itself performs no memory access."
  ],
  "operands": [
    {
      "field": "simm25",
      "role": "25-bit signed bundle target displacement"
    }
  ],
  "ordering": [
    "Decode and candidate-target validation precede retiring-block commit; successful commit precedes atomic publication of the new BARG."
  ],
  "standalone_opcode": true,
  "state_effects": [
    "DIRECT installs BARG.BPC=P, BlockType=STD, BPCN=P+(SignExtend(simm25)<<1), TYPE=DIRECT, TAKEN=1.",
    "COND installs the same BPC/BlockType/BPCN fields with TYPE=COND and TAKEN=0; SETC.* may update TAKEN and SETC.TGT may update BPCN before commit.",
    "Neither form selects BPCN at decode; BSTOP or the next BSTART is the continuation boundary."
  ]
}

depends_on

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

id

PTO-BLOCK-BSTART

mnemonic

BSTART

summary

Initializes the single BARG continuation record after any retiring block commits successfully.

surface

block

{
  "classification": [
    "lifecycle"
  ],
  "documentation": "docs/block/lifecycle/BSTART.md",
  "id": "PTO-BLOCK-BSTART",
  "instruction_contract": {
    "artifact": "spec/evidence/instruction-contract-closure.json",
    "mnemonic": "BSTART",
    "ndf_clause": "PTO-INST-BLOCK-BSTART"
  },
  "mnemonic": "BSTART",
  "readiness_subjects": [
    "ADR-0009",
    "ADR-0032",
    "ADR-0052",
    "ADR-0059",
    "ADR-0061",
    "ADR-0075",
    "ADR-0077"
  ],
  "semantic_tests": [
    "PTO-AVS-BLOCK-BSTART-BARG-001",
    "PTO-AVS-BLOCK-BSTART-BPCN-ALIGN-001",
    "PTO-AVS-BLOCK-BSTART-COND-SETC-001"
  ],
  "source": "asl/block/lifecycle/BSTART.asl",
  "surface": "block",
  "tests": [
    "PTO-AVS-BLOCK-BSTART-BARG-001",
    "PTO-AVS-BLOCK-BSTART-BPCN-ALIGN-001",
    "PTO-AVS-BLOCK-BSTART-COND-SETC-001",
    "PTO-AVS-BLOCK-BSTART-DECODE-001"
  ]
}