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Added tag lwtools-4.4 for changeset 74b4e9f23c62
author lost@l-w.ca
date Wed, 10 Aug 2011 19:16:23 -0600
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1 LWASM 2.0
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2 =========
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4 LWASM is a cross-assembler for the MC6809 and HD6309 CPUs. It should
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5 assemble most reasonable EDTASM compatible source code. This document is not
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6 intended to teach assembly language for these CPUs but rather to document
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7 the behaviour of LWASM.
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10 TARGETS
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11 -------
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13 LWASM supports several targets for assembly. These are decb, raw, and obj.
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15 The raw target generates a raw binary output. This is useful for building
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16 ROMs and other items that are not intended to be loaded by any kind of
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17 loader. In this mode, the ORG directive is merely advisory and does not
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18 affect the output except for the addresses symbols are defined to have.
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20 The decb target generates output that can be loaded with the CLOADM or LOADM
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21 commands in Color Basic. There will be approximately one segment in the
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22 output file for every ORG statement after which any code is emitted. (That
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23 is, two ORG statements in a row will not generate two output segments.)
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24 This is approximately equivalent to running A/AO in EDTASM.
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26 The obj target generates output that is intended to be linked later with
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27 LWLINK. This target disallows the use of ORG for defining anything other
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28 than constants. In this target, source files consist of a number of sections
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29 (SECTION/ENDSECTION). Nothing outside of a section is permitted to cause any
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30 output at all. Use of an ORG statement within a section is an error. This
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31 target also permits tagging symbols for export (EXPORT) and marking a symbol
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32 as externally defined (IMPORT/EXTERN). The linker will resolve any external
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33 references at link time. Additionally, any inter-section references will be
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34 resolved by the linker. All code in each section is assembled with an
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35 implicit origin of 0. SETDP has no effect because the assembler has no idea
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36 what address the linker will assign to the code when it is linked. Any
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37 direct addressing modes will default to extended to allow for the linker to
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38 perform relocations. Intersegment references and external references will
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39 use 16 bit relative addressing but intrasegment internal references may use
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40 8 bit relative addressing. Forced 8 bit direct modes are probably an error
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41 but are permitted on the theory that the programmer might know something the
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42 assembler doesn't.
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