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#include "project.h"
static inline size_t
ring_next (volatile ring_t *r, size_t p)
{
p++;
if (p >= r->size)
p -= r->size;
return p;
}
void
ring_init (volatile 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 (volatile ring_t *r, uint8_t c)
{
size_t n = ring_next (r, r->write);
if (n == r->read)
return -EAGAIN;
r->data[r->write] = c;
r->write = n;
return 0;
}
int
ring_read_byte (volatile ring_t *r, uint8_t *c)
{
size_t n = ring_next (r, r->read);
if (r->read == r->write)
return -EAGAIN;
*c = r->data[r->read];
r->read = n;
return 0;
}
int
ring_write (volatile ring_t *r, uint8_t *buf, size_t len, int blocking)
{
while (len--) {
if (blocking) {
while (ring_write_byte (r, *buf));
buf++;
} else {
if (ring_write_byte (r, * (buf++)))
return -EAGAIN;
}
}
return 0;
}
int
ring_empty (volatile ring_t *r)
{
return (r->read == r->write) ? 1 : 0;
}
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