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/*
* gensio - A library for abstracting stream I/O
* Copyright (C) 2018 Corey Minyard <minyard@acm.org>
*
* SPDX-License-Identifier: LGPL-2.1-only
*/
#include <string.h>
#include <assert.h>
#include <gensio/gensio_circbuf.h>
#include <gensio/gensio_os_funcs.h>
struct gensio_circbuf {
struct gensio_os_funcs *o;
gensiods pos;
gensiods size;
gensiods bufsize;
unsigned char *cbuf;
};
gensiods
gensio_circbuf_room_left(struct gensio_circbuf *c)
{
return c->bufsize - c->size;
}
void
gensio_circbuf_next_write_area(struct gensio_circbuf *c,
void **pos, gensiods *size)
{
gensiods end;
end = (c->pos + c->size) % c->bufsize;
if (c->size == c->bufsize)
*size = 0;
else if (end >= c->pos)
/* Unwrapped or empty buffer, write to the end. */
*size = c->bufsize - end;
else
/* Wrapped or full buffer, write between end and iopos. */
*size = c->pos - end;
*pos = c->cbuf + end;
}
void
gensio_circbuf_data_added(struct gensio_circbuf *c, gensiods len)
{
assert(len + c->size <= c->bufsize);
c->size += len;
}
void
gensio_circbuf_next_read_area(struct gensio_circbuf *c,
void **pos, gensiods *size)
{
gensiods end;
end = (c->pos + c->size) % c->bufsize;
if (c->size == 0)
*size = 0;
else if (end > c->pos)
/* Unwrapped buffer, read the whole thing. */
*size = c->size;
else
/* Wrapped buffer, read to end. */
*size = c->bufsize - c->pos;
*pos = c->cbuf + c->pos;
}
void
gensio_circbuf_data_removed(struct gensio_circbuf *c, gensiods len)
{
assert(len <= c->size);
c->size -= len;
c->pos = (c->pos + len) % c->bufsize;
}
gensiods
gensio_circbuf_datalen(struct gensio_circbuf *c)
{
return c->size;
}
void
gensio_circbuf_reset(struct gensio_circbuf *c)
{
c->pos = 0;
c->size = 0;
}
void
gensio_circbuf_sg_write(struct gensio_circbuf *c,
const struct gensio_sg *sg, gensiods sglen,
gensiods *rcount)
{
gensiods i, count = 0;
for (i = 0; i < sglen && gensio_circbuf_room_left(c) > 0; i++) {
gensiods buflen = sg[i].buflen;
const unsigned char *buf = sg[i].buf;
while (gensio_circbuf_room_left(c) && buflen > 0) {
gensiods size;
void *pos;
gensio_circbuf_next_write_area(c, &pos, &size);
if (size > buflen)
size = buflen;
memcpy(pos, buf, size);
gensio_circbuf_data_added(c, size);
buf += size;
buflen -= size;
count += size;
}
}
if (rcount)
*rcount = count;
}
void
gensio_circbuf_read(struct gensio_circbuf *c,
void *ibuf, gensiods buflen, gensiods *rcount)
{
gensiods count = 0;
unsigned char *buf = ibuf;
while (buflen > 0 && gensio_circbuf_datalen(c)) {
void *pos;
gensiods size;
gensio_circbuf_next_read_area(c, &pos, &size);
if (size > buflen)
size = buflen;
if (buf)
memcpy(buf, pos, size);
buflen -= size;
count += size;
if (buf)
buf += size;
gensio_circbuf_data_removed(c, size);
}
if (rcount)
*rcount = count;
}
struct gensio_circbuf *
gensio_circbuf_alloc(struct gensio_os_funcs *o, gensiods size)
{
struct gensio_circbuf *c;
c = o->zalloc(o, sizeof(*c));
if (!c)
return NULL;
c->o = o;
c->cbuf = o->zalloc(o, size);
if (!c->cbuf) {
o->free(o, c);
return NULL;
}
c->bufsize = size;
return c;
}
void
gensio_circbuf_free(struct gensio_circbuf *c)
{
c->o->free(c->o, c->cbuf);
c->o->free(c->o, c);
}
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