Expressions

    Expression precision

    TASM always uses 32-bit arithmetic in Ideal mode. In MASM mode, TASM
    uses either 16- or 32-bit arithmetic depending on whether you select
    the 80386 processor. Therefore, some expressions might produce
    different results depending on which processor you've selected. For
    example,

            (1000h * 1000h) / 1000h

    evaluates to 1000h if you select the ≥80386 processor, or to zero if
    you select the 8086, 80186, or 80286 processors.


    Symbols in expressions

    Standard symbol values

    The following symbols always represent specific values and don't have
    to be defined for you to use them:

    Symbol      Value
    ──────      ─────
    $           Current location counter
    NOTHING      0
    ?            0
    UNKNOWN      0
    BYTE         1
    WORD         2
    DWORD        4
    FWORD        6
    PWORD        6
    QWORD        8
    TBYTE       10
    NEAR        0ffffh
    FAR         0fffeh
    PROC        Either 0ffffh or 0fffeh, depending on current MODEL
    CODEPTR     Either 2 or 4, depending on current MODEL
    DATAPTR     Either 2 or 4, depending on current MODEL


    Simple symbol values

    TASM returns the following values for symbols used by themselves:

    Expression               Value
    ──────────               ─────
    address_name             Returns the address
    numerical_expr_name      Returns the value of the numerical expression
    table_name |             Returns the default value for the table member
      table_member_name      specified in the definition of the table
    struc/table_member_name  Returns the offset of the member within the
                             structure or table (MASM mode only)
    record_name              Returns a mask where the bits reserved to
                             represent bit fields in the record definition
                             are 1, the rest are 0
    record_name <...>        Returns the initial value a record instance
                             would have if it were declared with the same
                             text enclosed in angle brackets
    record_name {...}        Similar to record_name <...>
    record_field_name        Returns the number of bits the field is
                             displaced from the low order bit of the
                             record (also known as the shift value)
    enum_name                Returns a mask where the bits required to
                             represent the maximum value present in the
                             enum definition are 1, the rest are 0
    segment_name             Returns the segment value
    group_name               Returns the group value
    struc/union_name         Returns the size in bytes of the structure or
                             union, but only if it is 1, 2, or 4; all
                             other sizes return a value of 0
    type_name                If the type is defined as a synonym for a
                             structure or union, the value returned is the
                             same as for a structure or union. Otherwise,
                             the size of the type is returned (with 0ffffh
                             for short and near labels, and 0fffeh for far
                             labels)
    proctype_name            Returns 0ffffh if the proctype describes a
                             near procedure, or 0fffeh for a far procedure

    All other symbols return the value zero (0).

    Note that when you use a text macro name in an expression, Turbo
    Assembler substitutes the string value of the text macro for the text
    macro symbol. Similarly, when you use an alias name, TASM substitutes
    the symbol value that the alias represents for the alias symbol.