diff options
Diffstat (limited to 'include/util.h')
| -rw-r--r-- | include/util.h | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/include/util.h b/include/util.h index ed30ed4e46..0408940b35 100644 --- a/include/util.h +++ b/include/util.h @@ -101,4 +101,51 @@ int tolower(int c); */ int uint64divmod(uint64_t *v, int by); + +/****************************************************************************/ +/* Conditional stuff. + * + * We often need to watch for transitions between one state and another, so + * that we can issue warnings or take action ONCE. This abstracts that "have I + * already reacted to this" stuff into a single set of functions. + * + * For example: + * + * cond_t c; + * + * cond_init_false(&c); + * + * while(1) { + * int val = read_some_gpio(); + * cond_set(&c, val); + * + * if (cond_went_true(&c)) + * host_event(SOMETHING_HAPPENED); + * } + * + */ +typedef uint8_t cond_t; + +/* Initialize a conditional to a specific state. Do this first. */ +void cond_init(cond_t *c, int boolean); +static inline void cond_init_false(cond_t *c) { cond_init(c, 0); } +static inline void cond_init_true(cond_t *c) { cond_init(c, 1); } + +/* Set the current state. Do this as often as you like. */ +void cond_set(cond_t *c, int boolean); +static inline void cond_set_false(cond_t *c) { cond_set(c, 0); } +static inline void cond_set_true(cond_t *c) { cond_set(c, 1); } + +/* Get the current state. Do this as often as you like. */ +int cond_is(cond_t *c, int boolean); +static inline int cond_is_false(cond_t *c) { return cond_is(c, 0); } +static inline int cond_is_true(cond_t *c) { return cond_is(c, 1); } + +/* See if the state has transitioned. If it has, the corresponding function + * will return true ONCE only, until it's changed back. + */ +int cond_went(cond_t *c, int boolean); +static inline int cond_went_false(cond_t *c) { return cond_went(c, 0); } +static inline int cond_went_true(cond_t *c) { return cond_went(c, 1); } + #endif /* __CROS_EC_UTIL_H */ |