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| -rw-r--r-- | CODING_STYLE | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/CODING_STYLE b/CODING_STYLE index 2fa0c0b65b..12ba58ee29 100644 --- a/CODING_STYLE +++ b/CODING_STYLE @@ -123,3 +123,38 @@ We use traditional C-style /* */ comments and avoid // comments. Rationale: The // form is valid in C99, so this is purely a matter of consistency of style. The checkpatch script will warn you about this. + +8. trace-events style + +8.1 0x prefix + +In trace-events files, use a '0x' prefix to specify hex numbers, as in: + +some_trace(unsigned x, uint64_t y) "x 0x%x y 0x" PRIx64 + +An exception is made for groups of numbers that are hexadecimal by +convention and separated by the symbols '.', '/', ':', or ' ' (such as +PCI bus id): + +another_trace(int cssid, int ssid, int dev_num) "bus id: %x.%x.%04x" + +However, you can use '0x' for such groups if you want. Anyway, be sure that +it is obvious that numbers are in hex, ex.: + +data_dump(uint8_t c1, uint8_t c2, uint8_t c3) "bytes (in hex): %02x %02x %02x" + +Rationale: hex numbers are hard to read in logs when there is no 0x prefix, +especially when (occasionally) the representation doesn't contain any letters +and especially in one line with other decimal numbers. Number groups are allowed +to not use '0x' because for some things notations like %x.%x.%x are used not +only in Qemu. Also dumping raw data bytes with '0x' is less readable. + +8.2 '#' printf flag + +Do not use printf flag '#', like '%#x'. + +Rationale: there are two ways to add a '0x' prefix to printed number: '0x%...' +and '%#...'. For consistency the only one way should be used. Arguments for +'0x%' are: + - it is more popular + - '%#' omits the 0x for the value 0 which makes output inconsistent |