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| author | lost |
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| date | Fri, 19 Mar 2010 02:54:14 +0000 |
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| 338:e7885b3ee266 | 339:eb230fa7d28e |
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| 1 LWASM 2.0 | |
| 2 ========= | |
| 3 | |
| 4 LWASM is a cross-assembler for the MC6809 and HD6309 CPUs. It should | |
| 5 assemble most reasonable EDTASM compatible source code. This document is not | |
| 6 intended to teach assembly language for these CPUs but rather to document | |
| 7 the behaviour of LWASM. | |
| 8 | |
| 9 | |
| 10 TARGETS | |
| 11 ------- | |
| 12 | |
| 13 LWASM supports several targets for assembly. These are decb, raw, and obj. | |
| 14 | |
| 15 The raw target generates a raw binary output. This is useful for building | |
| 16 ROMs and other items that are not intended to be loaded by any kind of | |
| 17 loader. In this mode, the ORG directive is merely advisory and does not | |
| 18 affect the output except for the addresses symbols are defined to have. | |
| 19 | |
| 20 The decb target generates output that can be loaded with the CLOADM or LOADM | |
| 21 commands in Color Basic. There will be approximately one segment in the | |
| 22 output file for every ORG statement after which any code is emitted. (That | |
| 23 is, two ORG statements in a row will not generate two output segments.) | |
| 24 This is approximately equivalent to running A/AO in EDTASM. | |
| 25 | |
| 26 The obj target generates output that is intended to be linked later with | |
| 27 LWLINK. This target disallows the use of ORG for defining anything other | |
| 28 than constants. In this target, source files consist of a number of sections | |
| 29 (SECTION/ENDSECTION). Nothing outside of a section is permitted to cause any | |
| 30 output at all. Use of an ORG statement within a section is an error. This | |
| 31 target also permits tagging symbols for export (EXPORT) and marking a symbol | |
| 32 as externally defined (IMPORT/EXTERN). The linker will resolve any external | |
| 33 references at link time. Additionally, any inter-section references will be | |
| 34 resolved by the linker. All code in each section is assembled with an | |
| 35 implicit origin of 0. SETDP has no effect because the assembler has no idea | |
| 36 what address the linker will assign to the code when it is linked. Any | |
| 37 direct addressing modes will default to extended to allow for the linker to | |
| 38 perform relocations. Intersegment references and external references will | |
| 39 use 16 bit relative addressing but intrasegment internal references may use | |
| 40 8 bit relative addressing. Forced 8 bit direct modes are probably an error | |
| 41 but are permitted on the theory that the programmer might know something the | |
| 42 assembler doesn't. | |
| 43 |