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diff docs/manual/c941.html @ 254:155799f6cfa5
Add documentation for the FILL pseudo operation
| author | William Astle <lost@l-w.ca> |
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| date | Wed, 30 Jan 2013 21:32:14 -0700 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/docs/manual/c941.html Wed Jan 30 21:32:14 2013 -0700 @@ -0,0 +1,376 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd"> +<HTML +><HEAD +><TITLE +>Object Files</TITLE +><META +NAME="GENERATOR" +CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK +REL="HOME" +TITLE="LW Tool Chain" +HREF="index.html"><LINK +REL="PREVIOUS" +TITLE="Libraries and LWAR" +HREF="c879.html"></HEAD +><BODY +CLASS="CHAPTER" +BGCOLOR="#FFFFFF" +TEXT="#000000" +LINK="#0000FF" +VLINK="#840084" +ALINK="#0000FF" +><DIV +CLASS="NAVHEADER" +><TABLE +SUMMARY="Header navigation table" +WIDTH="100%" +BORDER="0" +CELLPADDING="0" +CELLSPACING="0" +><TR +><TH +COLSPAN="3" +ALIGN="center" +>LW Tool Chain</TH +></TR +><TR +><TD +WIDTH="10%" +ALIGN="left" +VALIGN="bottom" +><A +HREF="c879.html" +ACCESSKEY="P" +>Prev</A +></TD +><TD +WIDTH="80%" +ALIGN="center" +VALIGN="bottom" +></TD +><TD +WIDTH="10%" +ALIGN="right" +VALIGN="bottom" +> </TD +></TR +></TABLE +><HR +ALIGN="LEFT" +WIDTH="100%"></DIV +><DIV +CLASS="CHAPTER" +><H1 +><A +NAME="OBJCHAP" +></A +>Chapter 6. Object Files</H1 +><P +>LWTOOLS uses a proprietary object file format. It is proprietary in the sense +that it is specific to LWTOOLS, not that it is a hidden format. It would be +hard to keep it hidden in an open source tool chain anyway. This chapter +documents the object file format.</P +><P +>An object file consists of a series of sections each of which contains a +list of exported symbols, a list of incomplete references, and a list of +"local" symbols which may be used in calculating incomplete references. Each +section will obviously also contain the object code.</P +><P +>Exported symbols must be completely resolved to an address within the +section it is exported from. That is, an exported symbol must be a constant +rather than defined in terms of other symbols.</P +><P +>Each object file starts with a magic number and version number. The magic +number is the string "LWOBJ16" for this 16 bit object file format. The only +defined version number is currently 0. Thus, the first 8 bytes of the object +file are <FONT +COLOR="RED" +>4C574F424A313600</FONT +></P +><P +>Each section has the following items in order:</P +><P +></P +><UL +><LI +><P +>section name</P +></LI +><LI +><P +>flags</P +></LI +><LI +><P +>list of local symbols (and addresses within the section)</P +></LI +><LI +><P +>list of exported symbols (and addresses within the section)</P +></LI +><LI +><P +>list of incomplete references along with the expressions to calculate them</P +></LI +><LI +><P +>the actual object code (for non-BSS sections)</P +></LI +></UL +><P +>The section starts with the name of the section with a NUL termination +followed by a series of flag bytes terminated by NUL. There are only two +flag bytes defined. A NUL (0) indicates no more flags and a value of 1 +indicates the section is a BSS section. For a BSS section, no actual +code is included in the object file.</P +><P +>Either a NULL section name or end of file indicate the presence of no more +sections.</P +><P +>Each entry in the exported and local symbols table consists of the symbol +(NUL terminated) followed by two bytes which contain the value in big endian +order. The end of a symbol table is indicated by a NULL symbol name.</P +><P +>Each entry in the incomplete references table consists of an expression +followed by a 16 bit offset where the reference goes. Expressions are +defined as a series of terms up to an "end of expression" term. Each term +consists of a single byte which identifies the type of term (see below) +followed by any data required by the term. Then end of the list is flagged +by a NULL expression (only an end of expression term).</P +><DIV +CLASS="TABLE" +><A +NAME="AEN966" +></A +><P +><B +>Table 6-1. Object File Term Types</B +></P +><TABLE +BORDER="1" +FRAME="border" +CLASS="CALSTABLE" +><COL><COL><THEAD +><TR +><TH +>TERMTYPE</TH +><TH +>Meaning</TH +></TR +></THEAD +><TBODY +><TR +><TD +>00</TD +><TD +>end of expression</TD +></TR +><TR +><TD +>01</TD +><TD +>integer (16 bit in big endian order follows)</TD +></TR +><TR +><TD +>02</TD +><TD +> external symbol reference (NUL terminated symbol name follows)</TD +></TR +><TR +><TD +>03</TD +><TD +>local symbol reference (NUL terminated symbol name follows)</TD +></TR +><TR +><TD +>04</TD +><TD +>operator (1 byte operator number)</TD +></TR +><TR +><TD +>05</TD +><TD +>section base address reference</TD +></TR +><TR +><TD +>FF</TD +><TD +>This term will set flags for the expression. Each one of these terms will set a single flag. All of them should be specified first in an expression. If they are not, the behaviour is undefined. The byte following is the flag. Flag 01 indicates an 8 bit relocation. Flag 02 indicates a zero-width relocation (see the EXTDEP pseudo op in LWASM).</TD +></TR +></TBODY +></TABLE +></DIV +><P +>External references are resolved using other object files while local +references are resolved using the local symbol table(s) from this file. This +allows local symbols that are not exported to have the same names as +exported symbols or external references.</P +><DIV +CLASS="TABLE" +><A +NAME="AEN996" +></A +><P +><B +>Table 6-2. Object File Operator Numbers</B +></P +><TABLE +BORDER="1" +FRAME="border" +CLASS="CALSTABLE" +><COL><COL><THEAD +><TR +><TH +>Number</TH +><TH +>Operator</TH +></TR +></THEAD +><TBODY +><TR +><TD +>01</TD +><TD +>addition (+)</TD +></TR +><TR +><TD +>02</TD +><TD +>subtraction (-)</TD +></TR +><TR +><TD +>03</TD +><TD +>multiplication (*)</TD +></TR +><TR +><TD +>04</TD +><TD +>division (/)</TD +></TR +><TR +><TD +>05</TD +><TD +>modulus (%)</TD +></TR +><TR +><TD +>06</TD +><TD +>integer division (\) (same as division)</TD +></TR +><TR +><TD +>07</TD +><TD +>bitwise and</TD +></TR +><TR +><TD +>08</TD +><TD +>bitwise or</TD +></TR +><TR +><TD +>09</TD +><TD +>bitwise xor</TD +></TR +><TR +><TD +>0A</TD +><TD +>boolean and</TD +></TR +><TR +><TD +>0B</TD +><TD +>boolean or</TD +></TR +><TR +><TD +>0C</TD +><TD +>unary negation, 2's complement (-)</TD +></TR +><TR +><TD +>0D</TD +><TD +>unary 1's complement (^)</TD +></TR +></TBODY +></TABLE +></DIV +><P +>An expression is represented in a postfix manner with both operands for +binary operators preceding the operator and the single operand for unary +operators preceding the operator.</P +></DIV +><DIV +CLASS="NAVFOOTER" +><HR +ALIGN="LEFT" +WIDTH="100%"><TABLE +SUMMARY="Footer navigation table" +WIDTH="100%" +BORDER="0" +CELLPADDING="0" +CELLSPACING="0" +><TR +><TD +WIDTH="33%" +ALIGN="left" +VALIGN="top" +><A +HREF="c879.html" +ACCESSKEY="P" +>Prev</A +></TD +><TD +WIDTH="34%" +ALIGN="center" +VALIGN="top" +><A +HREF="index.html" +ACCESSKEY="H" +>Home</A +></TD +><TD +WIDTH="33%" +ALIGN="right" +VALIGN="top" +> </TD +></TR +><TR +><TD +WIDTH="33%" +ALIGN="left" +VALIGN="top" +>Libraries and LWAR</TD +><TD +WIDTH="34%" +ALIGN="center" +VALIGN="top" +> </TD +><TD +WIDTH="33%" +ALIGN="right" +VALIGN="top" +> </TD +></TR +></TABLE +></DIV +></BODY +></HTML +> \ No newline at end of file