MAXU

assembly

[
  "maxu SrcL, SrcR, ->{t, u, Rd}"
]

block

[]

catalog_indices

[
  359
]

catalog_records

[
  {
    "asm": "maxu SrcL, SrcR, ->{t, u, Rd}",
    "constraints": [],
    "encoding": [
      {
        "index": 0,
        "mask": "0xfe00707f",
        "match": "0x0800405b",
        "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": "SrcR",
        "pieces": [
          {
            "instruction_lsb": 20,
            "value_lsb": 0,
            "width": 5
          }
        ],
        "signedness": "encoding-defined",
        "width": 5
      }
    ],
    "form_id": "maxu_32_b8789571339d",
    "length_bits": 32,
    "mnemonic": "MAXU",
    "semantic_family": "ALU",
    "semantic_group": "ALU",
    "semantic_handler": "ScalarBinary",
    "semantic_summary": "MAXU performs an unsigned full-XLEN comparison and publishes the complete bit pattern of the maximum operand.",
    "status": "accepted"
  }
]

classification

[
  "alu"
]

contract

{
  "block_composition": [
    "none"
  ],
  "canonical_assembly": [
    "maxu SrcL, SrcR, ->{t, u, Rd}"
  ],
  "defaults": [
    "SrcL, SrcR, and RegDst are required fields; no field can be omitted.",
    "Encoded source zero reads the architectural zero GPR; encoded destination zero discards the result."
  ],
  "encoding_class": "standalone-encoded",
  "examples": [
    "maxu a0, a1, ->a2",
    "maxu t#1, u#1, ->u",
    "maxu zero, zero, ->zero"
  ],
  "exceptions": [
    "MAXU raises no arithmetic exception; comparison selects one unchanged operand bit pattern.",
    "Bits 31:25 are fixed by the accepted form. A mismatch or unavailable T/U source raises Fault_IllegalInstruction before the destination effect and TPC advance."
  ],
  "field_contracts": {},
  "field_zero_meanings": {
    "RegDst": "Encoded zero discards the result.",
    "SrcL": "Encoded zero reads the architectural zero GPR.",
    "SrcR": "Encoded zero reads the architectural zero GPR."
  },
  "legality": [
    "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.",
    "RegDst codes 0 and 24..29 discard, code 30 pushes U, code 31 pushes T, and codes 1..23 write GPRs.",
    "The operands use an unsigned full-XLEN comparison; every XLEN bit pattern is legal."
  ],
  "memory_effects": [
    "none"
  ],
  "operands": [
    {
      "field": "RegDst",
      "role": "Reg5 destination or discard"
    },
    {
      "field": "SrcL",
      "role": "left Reg5 source"
    },
    {
      "field": "SrcR",
      "role": "right Reg5 source"
    }
  ],
  "ordering": [
    "Snapshot both sources before the destination effect so repeated sources, destination aliases, and queue publication use pre-instruction values.",
    "Publish the selected operand, then advance TPC by four bytes."
  ],
  "standalone_opcode": true,
  "state_effects": [
    "Perform an unsigned full-XLEN comparison and return the complete bit pattern of the maximum operand; equal operands are observationally identical.",
    "Destination codes 0 and 24..29 discard, code 30 pushes U, code 31 pushes T, and codes 1..23 write GPRs; source queues are non-consuming.",
    "No memory, reservation, descriptor, numeric-flag, trap, block, privilege, or control-flow state changes except the successful TPC advance."
  ]
}

depends_on

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

id

PTO-SCALAR-MAXU

mnemonic

MAXU

summary

MAXU performs an unsigned full-XLEN comparison and publishes the complete bit pattern of the maximum operand.

surface

scalar

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