0xSCA/Rationale

0xSCA.xml

<section title="Design Rationale">
  <section title="Labels">
    <t>Although Notch used the syntax :label in his first
    examples, it is not common in any popular assembler.
    Thus we decided for label: as the recommended form,
    still silently allowing the deprecated form.</t>
    <t>To simplify writing reusable code we also introduced
    local labels, which are only visible from within the
    global label they are defined within. Implementing this
    is easy to do and introduces little overhead, as nesting
    is neither specified nor recommended.</t>
  </section>

  <section title="Preprocessor">
    <t>0xSCA allows many operators and even parentheses in
    expressions for if-clauses, which complicates the
    implementation of these. We do recognize that, but
    the actual implementation difficulty is not too high,
    as there are many examples how to achieve this and
    we think that the additional power and reduced
    code complexity, resulting in better maintainable
    code, is worth the effort.</t>
    <t>The ability to define custom constants inline is
    easy to implement and yields more easily maintainable
    code, while introducing a minimum of additional syntax.</t>
    <t>Both kinds of file inclusion support two different
    forms, one including the file relative to the current file,
    and the other including it from an implementation defined
    location. The former is ideal for splitting a program
    in multiple parts, while the latter is intended for
    implementation-provided resources such as source level
    libraries.</t>
    <t>A preprocessor must accept every directive with
    a dot (.) or a number sign (#) prefix. While Notch seems
    to prefer the latter, the former is much more common
    among todays assemblers. Thus we decided to support
    both, especiall as the implementation-side overhead is
    very low.</t>
  </section>
</section>