match_table

    OpenVMS usage:address
    type:         longword (unsigned)
    access:       read
    mechanism:    by 32-bit or 64-bit reference
    Describes the system fault match table. The match_table argument
    is the 32-bit or 64-bit virtual address of an array of longwords
    describing the system fault match table. The first longword is
    the number of match entries; the remaining longwords are the
    match entries.

    The match table is used to restrict the number of alignment
    faults reported. Each entry in the table is a bit mask divided
    into three groups: mode bits, program counter (PC) space bits,
    and virtual address (VA) space bits.

    The following table lists the symbols that can be used to define
    these bits:

    Bit Type       Symbols

    Mode bits      AME$M_KERNEL_MODE  Kernel mode
                   AME$M_EXEC_MODE    Executive mode
                   AME$M_SUPER_MODE   Supervisor mode
                   AME$M_USER_MODE    User mode
    Program        AME$M_USER_PC      PC in User space
    counter bits
                   AME$M_SYSTEM_PC    PC in System space
    Virtual        AME$M_SYSTEM_VA    VA in System space
    address bits
                   AME$M_USER_VA_P0   VA in User P0 space
                   AME$M_USER_VA_P1   VA in User P1 space
                   AME$M_USER_VA_P2   VA in User P2 space

    Refer to the VSI OpenVMS System Services Reference Manual to view
    the data structure of the match table.

    When an alignment fault occurs, a fault bit mask is created with
    one bit set in each group. The alignment fault handler then
    compares this fault bit mask against each entry in the match
    table. If the fault bit mask is a subset of an entry in the match
    table, the fault is reported.

 buffer_size

    OpenVMS usage:byte count
    type:         longword (signed)
    access:       read
    mechanism:    by value
    The number of bytes to allocate, from nonpaged pool, to save the
    alignment fault data. The buffer you allocate must be sufficient
    to accommodate one data item of the size specified in the flags
    argument.

 flags

    OpenVMS usage:mask_longword
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Flag bit mask specifying options for the $GET_SYS_ALIGN_FAULT_
    DATA operation.

    If the flags argument is 0, data items of size AFR$K_VMS_LENGTH
    will be returned. If the flags argument is AFR$M_USER_INFO, the
    user name and image name are added to each data item and they
    are returned in a buffer of length AFR$K_EXTENDED_LENGTH. If the
    user name and image name are not available, an empty string is
    returned in the data item.