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https://github.com/michaelcmartin/Ophis.git
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251 lines
4.4 KiB
HTML
251 lines
4.4 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<HTML
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><HEAD
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><TITLE
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>Headers, Libraries, and Macros</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK
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REL="HOME"
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TITLE="Programming with Ophis"
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HREF="book1.html"><LINK
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REL="UP"
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TITLE="Using the Ophis Assembler"
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HREF="p50.html"><LINK
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REL="PREVIOUS"
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TITLE="Aliasing"
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HREF="x248.html"><LINK
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REL="NEXT"
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TITLE="Macros"
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HREF="x284.html"></HEAD
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><BODY
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CLASS="CHAPTER"
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CELLSPACING="0"
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>Programming with Ophis</TH
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></TR
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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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WIDTH="80%"
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><TD
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VALIGN="bottom"
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>Next >>></A
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></TD
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></TR
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></TABLE
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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="CHAPTER"
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><H1
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><A
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NAME="CH3-LINK"
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></A
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>Headers, Libraries, and Macros</H1
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><P
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> In this chapter we will split away parts of our <SPAN
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CLASS="QUOTE"
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>"Hello
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World"</SPAN
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> program into reusable header files and libraries.
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We will also abstract away our string printing technique into a
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macro which may be invoked at will, on arbitrary strings. We will
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then multiply the output of our program tenfold.
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</P
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><DIV
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CLASS="SECTION"
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><H1
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CLASS="SECTION"
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><A
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NAME="AEN263"
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>Header files and libraries</A
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></H1
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><P
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> The prelude to our program—the <TT
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CLASS="FILENAME"
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>PRG</TT
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>
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information and the BASIC program—are going to be the same
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in many, many programs. Thus, we should put them into a header
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file to be included later. The <TT
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CLASS="LITERAL"
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>.include</TT
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>
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directive will load a file and insert it as source at the
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designated point.
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</P
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><P
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> A related directive, <TT
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CLASS="LITERAL"
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>.require</TT
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>, will include
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the file as long as it hasn't been included yet elsewhere. It
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is useful for ensuring a library is linked in.
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</P
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><P
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> For pre-assembled code or raw binary data,
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the <TT
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CLASS="LITERAL"
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>.incbin</TT
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> directive lets you include the
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contents of a binary file directly in the output. This is handy
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for linking in pre-created graphics or sound data.
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</P
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><P
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> If you only wish to include part of a binary
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file, <TT
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CLASS="LITERAL"
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>.incbin</TT
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> takes up to two optional
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arguments, naming the file offset at which to start reading and
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the number of characters to read.
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</P
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><P
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> As a sample library, we will expand the definition of
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the <TT
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CLASS="LITERAL"
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>chrout</TT
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> routine to include the standard
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names for every KERNAL routine. Our header file will
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then <TT
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CLASS="LITERAL"
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>.require</TT
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> it.
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</P
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><P
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> We'll also add some convenience aliases for things like reverse
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video, color changes, and shifting between upper case/graphics
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and mixed case text. We'd feed those to
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the <TT
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CLASS="LITERAL"
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>chrout</TT
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> routine to get their effects.
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</P
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><P
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> Since there have been no interesting changes to the prelude, and
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the KERNAL values are standard, we do not reproduce them here.
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(The files in question are <A
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HREF="x986.html"
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><I
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><I
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>c64-1.oph</I
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></I
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></A
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> and <A
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HREF="x990.html"
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><I
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><I
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>c64kernal.oph</I
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></I
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></A
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>.) The <TT
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CLASS="FILENAME"
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>c64kernal.oph</TT
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>
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header is likely to be useful in your own projects, and it is
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available in the <TT
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CLASS="LITERAL"
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>platform/</TT
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> directory for easy
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inclusion.
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</P
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></DIV
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></DIV
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><DIV
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CLASS="NAVFOOTER"
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><HR
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ALIGN="LEFT"
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WIDTH="100%"><TABLE
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SUMMARY="Footer navigation table"
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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><A
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HREF="x248.html"
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><<< Previous</A
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></TD
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WIDTH="34%"
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VALIGN="top"
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HREF="book1.html"
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>Home</A
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HREF="x284.html"
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>Next >>></A
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></TR
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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>Aliasing</TD
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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ALIGN="right"
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VALIGN="top"
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>Macros</TD
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></TR
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></BODY
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> |