NAME

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

SYNOPSIS

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

DESCRIPTION

       This module is a simple Imager::Expr compiler that compiles a low-level language that has
       a nearly 1-to-1 relationship to the internal representation used for compiled register
       machine code.

   Syntax
       Each line can contain multiple statements separated by semi-colons.

       Anything after '#' in a line is ignored.

       Types of statements:

       variable definition
               "var" name:type

           defines variable name to have type, which can be any of "n" or "num" for a numeric
           type or "pixel", "p" or "c" for a pixel or color type.

           Variable names cannot include white-space.

       operators
           Operators can be split into 3 basic types, those that have a result value, those that
           don't and the null operator, eg. jump has no value.

           The format for operators that return a value is typically:

               result = operator operand ...

           and for those that don't return a value:

               operator operand

           where operator is any valid register machine operator, result is any variable defined
           with "var", and operands are variables, constants or literals, or for jump operators,
           labels.

           The set operator can be simplified to:

               result = operator

           All operators maybe preceded by a label, which is any non-white-space text immediately
           followed by a colon (':').

BUGS

       Note that the current optimizer may produce incorrect optimization for your code,
       fortunately the optimizer will disable itself if you include any jump operator in your
       code.  A single jump to anywhere after your final "ret" operator can be used to disable
       the optimizer without slowing down your code.

       There's currently no high-level code generation that can generate code with loops or real
       conditions.

SEE ALSO

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

AUTHOR

       Tony Cook <tony@develop-help.com>