view docs/manual/x237.html @ 434:052c5f335a92

Fix bug in like terms collection in expression simplification Like term collection would lose the actual "variable" part of the term if the second term collected happened to have no coefficient. This would cause the expression to take the value of the calculated coefficient which is obviously wrong. Thanks to hider <stego@satx.rr.com> for reporting the bug and providing a proper test case. Observation: this bug has been present since the first pre-release of lwtools 3.0 when the algebraic expression system was introduced. Apparently people tend not to create expressions that trigger the like terms handler. The specific conditions require the symbol to be undefined and the second operand to the addition has to have no coefficient so it's likely a fairly rare scenario. Still, it is somewhat surprising that nobody tripped on it before now.
author William Astle <lost@l-w.ca>
date Mon, 23 Jan 2017 22:58:36 -0700
parents fc166b3bbae3
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>3.4. Symbols</A
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>Symbols have no length restriction. They may contain letters, numbers, dots,
dollar signs, and underscores. They must start with a letter, dot, or
underscore.</P
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>LWASM also supports the concept of a local symbol. A local symbol is one
which contains either a "?" or a "@", which can appear anywhere in the symbol.
The scope of a local symbol is determined by a number of factors. First,
each included file gets its own local symbol scope. A blank line will also
be considered a local scope barrier. Macros each have their own local symbol
scope as well (which has a side effect that you cannot use a local symbol
as an argument to a macro). There are other factors as well. In general,
a local symbol is restricted to the block of code it is defined within.</P
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>By default, unless assembling to the os9 target, a "$" in the symbol will
also make it local.  This can be controlled by the "dollarlocal" and
"nodollarlocal" pragmas.  In the absence of a pragma to the contrary, for
the os9 target, a "$" in the symbol will not make it considered local while
for all other targets it will.</P
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