1Imager::Expr::Assem(3)User Contributed Perl DocumentationImager::Expr::Assem(3)
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NAME

6         Imager::Expr::Assem - an assembler for producing code for the Imager
7         register machine
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SYNOPSIS

10         use Imager::Expr::Assem;
11         my $expr = Imager::Expr->new(assem=>'...', ...)
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DESCRIPTION

14       This module is a simple Imager::Expr compiler that compiles a low-level
15       language that has a nearly 1-to-1 relationship to the internal repre‐
16       sentation used for compiled regmach code.
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18       Syntax
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20       Each line can contain multiple statements separated by semi-colons.
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22       Anything after '#' in a line is ignored.
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24       Types of statements:
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26       variable definition
27               "var" name:type
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29           defines variable name to have type, which can be any of 'n' or
30           'num' for a numeric type or 'pixel', 'p' or 'c' for a pixel or
31           color type.
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33           Variable names cannot include whitespace.
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35       operators
36           Operators can be split into 3 basic types, those that have a result
37           value, those that don't and the null operator, eg. jump has no
38           value.
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40           The format for operators that return a value is typically:
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42               result = operator operand ...
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44           and for those that don't return a value:
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46               operator operand
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48           where operator is any valid regmach operator, result is any vari‐
49           able defined with "var", and operands are variables, constants or
50           literals, or for jump operators, labels.
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52           The set operator can be simplified to:
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54               result = operator
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56           All operators maybe preceded by a label, which is any non-white‐
57           space text immediately followed by a colon (':').
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BUGS

60       Note that the current optimizer may produce incorrect optimization for
61       your code, fortunately the optimizer will disable itself if you include
62       any jump operator in your code.  A single jump to anywhere after your
63       final ret operator can be used to disable the optimizer without slowing
64       down your code.
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66       There's currently no high-level code generation that can generate code
67       with loops or real conditions.
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SEE ALSO

70       Imager(3), transform.perl, regmach.c
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AUTHOR

73       Tony Cook <tony@develop-help.com>
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77perl v5.8.8                       2008-03-28            Imager::Expr::Assem(3)