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Update to gcc6809lw patch which may help compilation of some sources Due to persistent random compiler crashes and errors related to "M_REGS", this patch update (4.6.4-2) essentially removes the varius constraints allowing the "soft registers" in most operations. It was causing more problems than it solved and it is not clear that the logic behind those soft registers even makes sense any more. This patch also fixes a bogus comparison related to selecting the right size for a constant. Instead of the excessively clever comparison scheme that was previously in use, the comparisons have been replaced with straight forward comparisions for the top and bottom of the relevant 2's complement ranges.
author William Astle <lost@l-w.ca>
date Mon, 20 Jul 2015 22:32:41 -0600
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1 LWASM Internals
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2 ===============
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3
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4 LWASM is a table-driven assembler that notionally uses two passes. However,
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5 it implements its assembly in several passes as follows.
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7 Pass 1
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8 ------
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10 This pass reads the entire source code and parses each line into an internal
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11 representation. Macros, file inclusions, and conditional assembly
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12 instructions are resolved at this point as well. Instructions with known
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13 sizes will have their sizes resolved at this point.
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15 Pass 2
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16 ------
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18 Check all exported symbols for validity and set them as imports if the
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19 assembler state says so. Also resolve all symbol references in all
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20 expressions to be direct references either to the symbol table or
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21 to the import list.
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23 Pass 3
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24 ------
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26 This pass resolves all instruction sizes that can be resolved without
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27 forcing any instruction sizes. This pass will run repeatedly until no
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28 no new resolution occurs.
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30 Pass 4
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31 ------
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33 Work through all un-resolved instructions and force sizes. After each size
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34 is forced, try re-resolving all other instructions. This is done starting
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35 at the beginning of the source and working forward. If any instruction does
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36 not resolve when forced, an error will be thrown.
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38 Pass 5
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39 ------
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41 Constantize all line addresses and throw errors if any cannot be. This
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42 pass will repeat until no further lines addresses are reduced to constants
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43 at which time all lines will be checked for constant-ness.
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45 Pass 6
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46 ------
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48 Finalize all expressions related to instructions. Carp about any that
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49 cannot be reduced to a usable form. That means, for the non-object target
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50 all expressions must resolve to a constant. For the object form, all
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51 expressions must resolve to symbol references and constants. Those symbol
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52 references may be internal or external.
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54 Pass 7
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55 ------
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57 Emit object code for each line for later output.