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Added pbuf_get_contiguous() to get data in one piece (either zero copy from pbuf or memcpied into a supplied buffer)

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goldsimon 2017-02-24 21:36:49 +01:00
parent a38e937dd6
commit 0da9cf70ea
2 changed files with 42 additions and 0 deletions
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41
src/core/pbuf.c
View File

@ -1056,6 +1056,47 @@ pbuf_copy_partial(const struct pbuf *buf, void *dataptr, u16_t len, u16_t offset
return copied_total;
}
/** Get part of a pbuf's payload as contiguous memory. The returned memory is
* either a pointer into the pbuf's payload or, if split over multiple pbufs,
* a copy into the user-supplied buffer.
*
* @param p the pbuf from which to copy data
* @param dataptr the application supplied buffer
* @param len length of data to copy (dataptr must be big enough). No more
* than buf->tot_len will be copied, irrespective of len
* @param offset offset into the packet buffer from where to begin copying len bytes
* @return the number of bytes copied, or 0 on failure
*/
void *
pbuf_get_contiguous(const struct pbuf *p, void *buffer, size_t bufsize, u16_t len, u16_t offset)
{
const struct pbuf *q;
LWIP_ERROR("pbuf_get_contiguous: invalid buf", (p != NULL), return NULL;);
LWIP_ERROR("pbuf_get_contiguous: invalid dataptr", (buffer != NULL), return NULL;);
LWIP_ERROR("pbuf_get_contiguous: invalid dataptr", (bufsize >= len), return NULL;);
for (q = p; q != NULL; q = q->next) {
if ((offset != 0) && (offset >= q->len)) {
/* don't copy from this buffer -> on to the next */
offset -= q->len;
} else {
if (q->len >= (offset + len)) {
/* all data in this pbuf, return zero-copy */
return (u8_t*)q->payload + offset;
}
/* need to copy */
if (pbuf_copy_partial(q, buffer, len, offset) != len) {
/* copying failed: pbuf is too short */
return NULL;
}
return buffer;
}
}
/* pbuf is too short (offset does not fit in) */
return NULL;
}
#if LWIP_TCP && TCP_QUEUE_OOSEQ && LWIP_WND_SCALE
/**
* This method modifies a 'pbuf chain', so that its total length is

1
src/include/lwip/pbuf.h
View File

@ -240,6 +240,7 @@ void pbuf_chain(struct pbuf *head, struct pbuf *tail);
struct pbuf *pbuf_dechain(struct pbuf *p);
err_t pbuf_copy(struct pbuf *p_to, const struct pbuf *p_from);
u16_t pbuf_copy_partial(const struct pbuf *p, void *dataptr, u16_t len, u16_t offset);
void *pbuf_get_contiguous(const struct pbuf *p, void *buffer, size_t bufsize, u16_t len, u16_t offset);
err_t pbuf_take(struct pbuf *buf, const void *dataptr, u16_t len);
err_t pbuf_take_at(struct pbuf *buf, const void *dataptr, u16_t len, u16_t offset);
struct pbuf *pbuf_skip(struct pbuf* in, u16_t in_offset, u16_t* out_offset);