77ac486263
Signed-off-by: Avi Kivity <avi@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
82 lines
2.9 KiB
Plaintext
82 lines
2.9 KiB
Plaintext
Qemu Coding Style
|
|
=================
|
|
|
|
1. Whitespace
|
|
|
|
Of course, the most important aspect in any coding style is whitespace.
|
|
Crusty old coders who have trouble spotting the glasses on their noses
|
|
can tell the difference between a tab and eight spaces from a distance
|
|
of approximately fifteen parsecs. Many a flamewar have been fought and
|
|
lost on this issue.
|
|
|
|
QEMU indents are four spaces. Tabs are never used, except in Makefiles
|
|
where they have been irreversibly coded into the syntax.
|
|
Spaces of course are superior to tabs because:
|
|
|
|
- You have just one way to specify whitespace, not two. Ambiguity breeds
|
|
mistakes.
|
|
- The confusion surrounding 'use tabs to indent, spaces to justify' is gone.
|
|
- Tab indents push your code to the right, making your screen seriously
|
|
unbalanced.
|
|
- Tabs will be rendered incorrectly on editors who are misconfigured not
|
|
to use tab stops of eight positions.
|
|
- Tabs are rendered badly in patches, causing off-by-one errors in almost
|
|
every line.
|
|
- It is the QEMU coding style.
|
|
|
|
Do not leave whitespace dangling off the ends of lines.
|
|
|
|
2. Line width
|
|
|
|
Lines are 80 characters; not longer.
|
|
|
|
Rationale:
|
|
- Some people like to tile their 24" screens with a 6x4 matrix of 80x24
|
|
xterms and use vi in all of them. The best way to punish them is to
|
|
let them keep doing it.
|
|
- Code and especially patches is much more readable if limited to a sane
|
|
line length. Eighty is traditional.
|
|
- It is the QEMU coding style.
|
|
|
|
3. Naming
|
|
|
|
Variables are lower_case_with_underscores; easy to type and read. Structured
|
|
type names are in CamelCase; harder to type but standing out. Scalar type
|
|
names are lower_case_with_underscores_ending_with_a_t, like the POSIX
|
|
uint64_t and family. Note that this last convention contradicts POSIX
|
|
and is therefore likely to be changed.
|
|
|
|
Typedefs are used to eliminate the redundant 'struct' keyword. It is the
|
|
QEMU coding style.
|
|
|
|
When wrapping standard library functions, use the prefix qemu_ to alert
|
|
readers that they are seeing a wrapped version; otherwise avoid this prefix.
|
|
|
|
4. Block structure
|
|
|
|
Every indented statement is braced; even if the block contains just one
|
|
statement. The opening brace is on the line that contains the control
|
|
flow statement that introduces the new block; the closing brace is on the
|
|
same line as the else keyword, or on a line by itself if there is no else
|
|
keyword. Example:
|
|
|
|
if (a == 5) {
|
|
printf("a was 5.\n");
|
|
} else if (a == 6) {
|
|
printf("a was 6.\n");
|
|
} else {
|
|
printf("a was something else entirely.\n");
|
|
}
|
|
|
|
An exception is the opening brace for a function; for reasons of tradition
|
|
and clarity it comes on a line by itself:
|
|
|
|
void a_function(void)
|
|
{
|
|
do_something();
|
|
}
|
|
|
|
Rationale: a consistent (except for functions...) bracing style reduces
|
|
ambiguity and avoids needless churn when lines are added or removed.
|
|
Furthermore, it is the QEMU coding style.
|