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/* See LICENSE file for copyright and license details. */
#include "types-ring.h"
#include <stdlib.h>
#include <string.h>
/**
* Initialise a ring buffer
*
* @param this The ring buffer
*/
void
ring_initialise(struct ring *restrict this)
{
this->start = 0;
this->end = 0;
this->size = 0;
this->buffer = NULL;
}
#if defined(__clang__)
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wcast-align"
#endif
/**
* Marshal a ring buffer
*
* @param this The ring buffer
* @param buf Output buffer for the marshalled data,
* `NULL` to only measure how large buffer
* is needed
* @return The number of marshalled bytes
*/
size_t
ring_marshal(const struct ring *restrict this, void *restrict buf)
{
size_t off = 0, n = this->end - this->start;
char *bs = buf;
if (bs)
*(size_t *)&bs[off] = n;
off += sizeof(size_t);
if (bs)
memcpy(&bs[off], this->buffer + this->start, n);
off += n;
return off;
}
/**
* Unmarshal a ring buffer
*
* @param this Output parameter for the ring buffer
* @param buf Buffer with the marshalled data
* @return The number of unmarshalled bytes, 0 on error
*/
size_t
ring_unmarshal(struct ring *restrict this, const void *restrict buf)
{
size_t off = 0;
const char *bs = buf;
ring_initialise(this);
this->size = this->end = *(const size_t *)&bs[off];
off += sizeof(size_t);
if (this->end > 0) {
this->buffer = malloc(this->end);
if (!this->buffer)
return 0;
memcpy(this->buffer, bs + off, this->end);
off += this->end;
}
return off;
}
#if defined(__clang__)
# pragma GCC diagnostic pop
#endif
/**
* Append data to a ring buffer
*
* @param this The ring buffer
* @param data The new data
* @param n The number of bytes in `data`
* @return Zero on success, -1 on error
*/
int
ring_push(struct ring *restrict this, void *restrict data, size_t n)
{
size_t used = 0;
char *restrict new;
if (this->start == this->end) {
if (this->buffer)
used = this->size;
} else if (this->start > this->end) {
used = this->size - this->start + this->end;
} else {
used = this->start - this->end;
}
if (used + n > this->size) {
new = malloc(used + n);
if (!new)
return -1;
if (this->buffer) {
if (this->start < this->end) {
memcpy(new, this->buffer + this->start, this->end - this->start);
} else {
memcpy(new, this->buffer + this->start, this->size - this->start);
memcpy(new + this->size - this->start, this->buffer, this->end);
}
}
memcpy(new + used, data, n);
this->buffer = new;
this->start = 0;
this->end = used + n;
this->size = used + n;
} else if (this->start >= this->end || this->end + n <= this->size) {
memcpy(&this->buffer[this->end], data, n);
this->end += n;
} else {
memcpy(&this->buffer[this->end], data, this->size - this->end);
data = &((char *)data)[this->size - this->end];
n -= this->size - this->end;
memcpy(this->buffer, data, n);
this->end = n;
}
return 0;
}
/**
* Get queued data from a ring buffer
*
* It can take up to two calls (with `ring_pop` between)
* to get all queued data
*
* @param this The ring buffer
* @param n Output parameter for the length
* of the returned segment
* @return The beginning of the queued data,
* `NULL` if there is nothing more
*/
void *
ring_peek(struct ring *restrict this, size_t *restrict n)
{
if (!this->buffer) {
*n = 0;
return NULL;
}
if (this->start < this->end)
*n = this->end - this->start;
else
*n = this->size - this->start;
return this->buffer + this->start;
}
/**
* Dequeue data from a ring bubber
*
* @param this The ring buffer
* @param n The number of bytes to dequeue
*/
void
ring_pop(struct ring *restrict this, size_t n)
{
this->start += n;
this->start %= this->size;
if (this->start == this->end) {
free(this->buffer);
this->start = 0;
this->end = 0;
this->size = 0;
this->buffer = NULL;
}
}
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