From 6d0f31f1dbc631d586ab25368b52cd84a02b3b4b Mon Sep 17 00:00:00 2001 From: Raul E Rangel Date: Thu, 4 Apr 2019 14:58:16 -0600 Subject: ec/common: Introduce IS_ENABLED to check config options This is copied from coreboot with added support for empty defines. We should favor using this macro instead of using #ifdef. The macro will evaluate to 0 if the option is not defined. This allows all the code to be compiled and then the optimizer will remove the sections of code that won't ever run. This way we don't end up with #ifdef sections with invalid syntax because no one ever tests that specific permutation. e.g., if (IS_ENABLED(CONFIG_USBC_SS_MUX)) { ... } There are currently spots where #ifdefs are nested 3 levels deep. This makes it very hard to follow the code. BUG=none TEST=Added some code that uses the macro and verified it executes when the config value is defined, and doesn't when it's not. Change-Id: I796b899f7cbbd3067ea3a4d52527d980c68935c9 Signed-off-by: Raul E Rangel Reviewed-on: https://chromium-review.googlesource.com/1553573 Commit-Ready: ChromeOS CL Exonerator Bot Reviewed-by: Daisuke Nojiri Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3105733 Reviewed-by: caveh jalali Commit-Queue: Daisuke Nojiri Tested-by: Daisuke Nojiri --- include/common.h | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/include/common.h b/include/common.h index 8897bb5b0e..e2ec79225b 100644 --- a/include/common.h +++ b/include/common.h @@ -258,4 +258,31 @@ enum ec_error_list { /* find the most significant bit. Not defined in n == 0. */ #define __fls(n) (31 - __builtin_clz(n)) +/* + * Getting something that works in C and CPP for an arg that may or may + * not be defined is tricky. Here, if we have "#define CONFIG_BOOGER" + * we match on the placeholder define, insert the "0," for arg1 and generate + * the triplet (0, 1, 0). Then the last step cherry picks the 2nd arg (a one). + * When CONFIG_BOOGER is not defined, we generate a (... 1, 0) pair, and when + * the last step cherry picks the 2nd arg, we get a zero. + */ +#define __ARG_PLACEHOLDER_ 0, +#define config_enabled(cfg) _config_enabled(cfg) +#define _config_enabled(value) __config_enabled(__ARG_PLACEHOLDER_##value) +#define __config_enabled(arg1_or_junk) ___config_enabled(arg1_or_junk 1, 0, 0) +#define ___config_enabled(__ignored, val, ...) val + +/** + * Checks if a config option is defined to an empty value. + * + * IS_ENABLED(CONFIG_MY_OPTION) will return 1 in the following case: + * #define CONFIG_MY_OPTION + * + * Otherwise if the option has not been defined or defined with a value, it will + * return 0. + * + * @param CONFIG_OPTION + */ +#define IS_ENABLED(option) config_enabled(option) + #endif /* __CROS_EC_COMMON_H */ -- cgit v1.2.1