Revision e68b98dc

b/CODING_STYLE
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Qemu Coding Style
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=================
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1. Whitespace
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Of course, the most important aspect in any coding style is whitespace.
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Crusty old coders who have trouble spotting the glasses on their noses
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can tell the difference between a tab and eight spaces from a distance
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of approximately fifteen parsecs.  Many a flamewar have been fought and
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lost on this issue.
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QEMU indents are four spaces.  Tabs are never used, except in Makefiles
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where they have been irreversibly coded into the syntax by some moron.
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Spaces of course are superior to tabs because:
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 - You have just one way to specify whitespace, not two.  Ambiguity breeds
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   mistakes.
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 - The confusion surrounding 'use tabs to indent, spaces to justify' is gone.
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 - Tab indents push your code to the right, making your screen seriously
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   unbalanced.
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 - Tabs will be rendered incorrectly on editors who are misconfigured not
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   to use tab stops of eight positions.
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 - Tabs are rendered badly in patches, causing off-by-one errors in almost
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   every line.
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 - It is the QEMU coding style.
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Do not leave whitespace dangling off the ends of lines.
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2. Line width
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Lines are 80 characters; not longer.
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Rationale:
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 - Some people like to tile their 24" screens with a 6x4 matrix of 80x24
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   xterms and use vi in all of them.  The best way to punish them is to
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   let them keep doing it.
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 - Code and especially patches is much more readable if limited to a sane
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   line length.  Eighty is traditional.
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 - It is the QEMU coding style.
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3. Naming
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Variables are lower_case_with_underscores; easy to type and read.  Structured
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type names are in CamelCase; harder to type but standing out.  Scalar type
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names are lower_case_with_underscores_ending_with_a_t, like the POSIX
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uint64_t and family.  Note that this last convention contradicts POSIX
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and is therefore likely to be changed.
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Typedefs are used to eliminate the redundant 'struct' keyword.  It is the
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QEMU coding style.
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4. Block structure
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Every indented statement is braced; even if the block contains just one
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statement.  The opening brace is on the line that contains the control
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flow statement that introduces the new block; the closing brace is on the
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same line as the else keyword, or on a line by itself if there is no else
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keyword.  Example:
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    if (a == 5) {
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        printf("a was 5.\n");
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    } else if (a == 6) {
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        printf("a was 6.\n");
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    } else {
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        printf("a was something else entirely.\n");
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    }
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An exception is the opening brace for a function; for reasons of tradition
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and clarity it comes on a line by itself:
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    void a_function(void)
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    {
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        do_something();
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    }
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Rationale: a consistent (except for functions...) bracing style reduces
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ambiguity and avoids needless churn when lines are added or removed.
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Furthermore, it is the QEMU coding style.

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