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"""
Specifies the ISA enum
"""

import os
from enum import Enum
from typing import Set


class ISA(Enum):
    """
    The ISA Enums which may be used in the gem5 stdlib to specify ISAs.

    Their value may be used to translate the ISA to strings and compare against
    inputs and environment variables.

    E.g., to check if the X86 ISA is compiled:

    ```
    if buildEnv[f"USE_{ISA.X86.value}_ISA"]:
        ...
    ```
    """

    X86 = "x86"
    RISCV = "riscv"
    ARM = "arm"
    MIPS = "mips"
    POWER = "power"
    SPARC = "sparc"
    NULL = "null"


def get_isas_str_set() -> Set[str]:
    """
    Returns a set of all the ISA as strings.
    """
    return {isa.value for isa in ISA}


def get_isa_from_str(input: str) -> ISA:
    """
    Will return the correct enum given the input string. This is matched on
    the enum's value. E.g., "x86" will return ISA.X86. Throws an exception if
    the input string is invalid.

    `get_isas_str_set()` can be used to determine the valid strings.

    This is for parsing text inputs that specify ISA targets.

    :param input: The ISA to return, as a string. Case-insensitive.
    """
    for isa in ISA:
        if input.lower() == isa.value:
            return isa

    valid_isas_str_list = str()
    for isa_str in get_isas_str_set():
        valid_isas_str_list += f"{os.linesep}{isa_str}"

    raise Exception(
        f"Value '{input}' does not correspond to a known ISA. Known ISAs:"
        f"{valid_isas_str_list}"
    )