X-Git-Url: https://repo.jachan.dev/qemu.git/blobdiff_plain/e68b98dc7237d76fdef5c5d403d0613b443102da..baca2b9e3a94be1690fc4a842a97b64a4c8f892c:/CODING_STYLE

diff --git a/CODING_STYLE b/CODING_STYLE
index 1ab13b6861..d46cfa5f65 100644
--- a/CODING_STYLE
+++ b/CODING_STYLE
@@ -1,6 +1,9 @@
-Qemu Coding Style
+QEMU Coding Style
 =================
 
+Please use the script checkpatch.pl in the scripts directory to check
+patches before submitting.
+
 1. Whitespace
 
 Of course, the most important aspect in any coding style is whitespace.
@@ -10,7 +13,7 @@ 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 by some moron.
+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
@@ -41,13 +44,14 @@ Rationale:
 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
+type names are in CamelCase; harder to type but standing out.  Enum type
+names and function type names should also be in CamelCase.  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
 
@@ -65,6 +69,10 @@ keyword.  Example:
         printf("a was something else entirely.\n");
     }
 
+Note that 'else if' is considered a single statement; otherwise a long if/
+else if/else if/.../else sequence would need an indent for every else
+statement.
+
 An exception is the opening brace for a function; for reasons of tradition
 and clarity it comes on a line by itself:
 
@@ -76,3 +84,24 @@ and clarity it comes on a line by itself:
 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.
+
+5. Declarations
+
+Mixed declarations (interleaving statements and declarations within blocks)
+are not allowed; declarations should be at the beginning of blocks.  In other
+words, the code should not generate warnings if using GCC's
+-Wdeclaration-after-statement option.
+
+6. Conditional statements
+
+When comparing a variable for (in)equality with a constant, list the
+constant on the right, as in:
+
+if (a == 1) {
+    /* Reads like: "If a equals 1" */
+    do_something();
+}
+
+Rationale: Yoda conditions (as in 'if (1 == a)') are awkward to read.
+Besides, good compilers already warn users when '==' is mis-typed as '=',
+even when the constant is on the right.