diff options
Diffstat (limited to 'stm32/app/ring.c')
-rw-r--r-- | stm32/app/ring.c | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/stm32/app/ring.c b/stm32/app/ring.c new file mode 100644 index 0000000..26bba3a --- /dev/null +++ b/stm32/app/ring.c @@ -0,0 +1,64 @@ +#include "project.h" + + +static inline size_t +ring_next (ring_t *r, size_t p) +{ + p++; + + if (p >= r->size) + p -= r->size; + + return p; +} + +void +ring_init (ring_t *r, uint8_t *buf, size_t len) +{ + r->data = buf; + r->size = len; + r->write = 0; + r->read = 0; +} + +int +ring_write_byte (ring_t *r, uint8_t c) +{ + size_t n = ring_next (r, r->write); + + if (n == r->read) + return -1; + + r->data[r->write] = c; + r->write = n; + return 0; +} + +int ring_empty (ring_t *r) +{ + return (r->read == r->write); +} + +int +ring_read_byte (ring_t *r, uint8_t *c) +{ + size_t n = ring_next (r, r->read); + + if (r->read == r->write) + return -1; + + *c = r->data[r->read]; + r->read = n; + return 0; +} + +int +ring_write (ring_t *r, uint8_t *buf, size_t len) +{ + while (len--) { + if (ring_write_byte (r, * (buf++))) + return -1; + } + + return 0; +} |