From fc3576ab06a33bd3733ea37341fd3b0094e1298c Mon Sep 17 00:00:00 2001 From: Yu-Ping Wu Date: Tue, 22 Jun 2021 17:40:01 +0800 Subject: helpers: Introduce retry macro Introduce a macro retry(attempts, condition, expr) for retrying a condition, which is extensively used in coreboot. Example usage: if (!retry(3, read32(REG) == 0, mdelay(1)) printk(BIOS_ERR, "Error waiting for REG to be 0\n"); BUG=none TEST=make tests/commonlib/bsd/helpers-test TEST=emerge-cherry coreboot BRANCH=none Change-Id: I421e4dcab949616bd68b3a14231da744b9f74eeb Signed-off-by: Yu-Ping Wu Reviewed-on: https://review.coreboot.org/c/coreboot/+/55778 Tested-by: build bot (Jenkins) Reviewed-by: Julius Werner --- src/commonlib/bsd/include/commonlib/bsd/helpers.h | 35 +++++++++++++++++++++++ 1 file changed, 35 insertions(+) (limited to 'src') diff --git a/src/commonlib/bsd/include/commonlib/bsd/helpers.h b/src/commonlib/bsd/include/commonlib/bsd/helpers.h index 4e6ebeefdd..376ebaef11 100644 --- a/src/commonlib/bsd/include/commonlib/bsd/helpers.h +++ b/src/commonlib/bsd/include/commonlib/bsd/helpers.h @@ -88,4 +88,39 @@ /* Calculate size of structure member. */ #define member_size(type, member) (sizeof(((type *)0)->member)) +#define _retry_impl(attempts, condition, expr, ...) \ +({ \ + __typeof__(condition) _retry_ret = \ + (__typeof__(condition))0; \ + int _retry_attempts = (attempts); \ + do { \ + _retry_ret = (condition); \ + if (_retry_ret) \ + break; \ + if (--_retry_attempts > 0) { \ + expr; \ + } else { \ + break; \ + } \ + } while (1); \ + _retry_ret; \ +}) + +/* + * Helper macro to retry until a condition becomes true or the maximum number + * of attempts is reached. Two forms are supported: + * + * 1. retry(attempts, condition) + * 2. retry(attempts, condition, expr) + * + * @param attempts Maximum attempts. + * @param condition Condition to retry for. + * @param expr Procedure to run between each evaluation to "condition". + * + * @return Condition value if it evaluates to true within the maximum attempts; + * 0 otherwise. + */ +#define retry(attempts, condition, ...) \ + _retry_impl(attempts, condition, __VA_ARGS__) + #endif /* COMMONLIB_BSD_HELPERS_H */ -- cgit v1.2.3