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lowpan6.c: implement software CRC (e.g. required for use with ZEP)

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This commit is contained in:
goldsimon 2018-02-28 21:39:38 +01:00
parent fe68fa49f7
commit 3a93029e92
3 changed files with 52 additions and 23 deletions
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2
src/include/netif/lowpan6.h
View File

@ -73,6 +73,8 @@ err_t lowpan6_if_init(struct netif *netif);
/* pan_id in network byte order. */
err_t lowpan6_set_pan_id(u16_t pan_id);
u16_t lowpan6_calc_crc(const void *buf, u16_t len);
#if !NO_SYS
err_t tcpip_6lowpan_input(struct pbuf *p, struct netif *inp);
#endif /* !NO_SYS */

6
src/include/netif/lowpan6_opts.h
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@ -60,7 +60,11 @@
#endif
#ifndef LWIP_6LOWPAN_HW_CRC
#define LWIP_6LOWPAN_HW_CRC 1
#define LWIP_6LOWPAN_HW_CRC 0
#endif
#ifndef LWIP_6LOWPAN_CALC_CRC
#define LWIP_6LOWPAN_CALC_CRC(buf, len) lowpan6_calc_crc(buf, len)
#endif
#ifndef LOWPAN6_DEBUG

67
src/netif/lowpan6.c
View File

@ -69,6 +69,12 @@
#error "6LoWPAN netif needs a 64-bit hwaddr"
#endif
#if LWIP_6LOWPAN_HW_CRC
#define LWIP_6LOWPAN_DO_CALC_CRC(buf, len) 0
#else
#define LWIP_6LOWPAN_DO_CALC_CRC(buf, len) LWIP_6LOWPAN_CALC_CRC(buf, len)
#endif
/** This is a helper struct for reassembly of fragments
* (IEEE 802.15.4 limits to 127 bytes)
*/
@ -289,6 +295,31 @@ lowpan6_parse_iee802154_header(struct pbuf *p, struct ieee_802154_addr *src,
return ERR_OK;
}
/** Calculate the 16-bit CRC as required by IEEE 802.15.4 */
u16_t
lowpan6_calc_crc(const void* buf, u16_t len)
{
#define CCITT_POLY_16 0x8408U
u16_t i;
u8_t b;
u16_t crc = 0;
const u8_t* p = (const u8_t*)buf;
for (i = 0; i < len; i++) {
u8_t data = *p;
for (b = 0U; b < 8U; b++) {
if (((data ^ crc) & 1) != 0) {
crc = (u16_t)((crc >> 1) ^ CCITT_POLY_16);
} else {
crc = (u16_t)(crc >> 1);
}
data = (u8_t)(data >> 1);
}
p++;
}
return crc;
}
#if LWIP_6LOWPAN_IPHC && LWIP_6LOWPAN_NUM_CONTEXTS > 0
static s8_t
lowpan6_context_lookup(const ip6_addr_t *ip6addr)
@ -370,6 +401,7 @@ lowpan6_frag(struct netif *netif, struct pbuf *p, const struct ieee_802154_addr
u8_t ieee_header_len;
u8_t lowpan6_header_len;
s8_t i;
u16_t crc;
u16_t datagram_offset;
err_t err = ERR_IF;
@ -627,15 +659,12 @@ lowpan6_frag(struct netif *netif, struct pbuf *p, const struct ieee_802154_addr
remaining_len -= frag_len - lowpan6_header_len;
datagram_offset = frag_len;
/* 2 bytes CRC */
#if LWIP_6LOWPAN_HW_CRC
/* Leave blank, will be filled by HW. */
#else /* LWIP_6LOWPAN_HW_CRC */
/* @todo calculate CRC */
#endif /* LWIP_6LOWPAN_HW_CRC */
/* Calculate frame length */
p_frag->len = p_frag->tot_len = ieee_header_len + 4 + frag_len + 2; /* add 2 dummy bytes for crc*/
p_frag->len = p_frag->tot_len = ieee_header_len + 4 + frag_len + 2; /* add 2 bytes for crc*/
/* 2 bytes CRC */
crc = LWIP_6LOWPAN_DO_CALC_CRC(p_frag->payload, p_frag->len - 2);
pbuf_take_at(p_frag, &crc, 2, p_frag->len - 2);
/* send the packet */
MIB2_STATS_NETIF_ADD(netif, ifoutoctets, p_frag->tot_len);
@ -660,16 +689,13 @@ lowpan6_frag(struct netif *netif, struct pbuf *p, const struct ieee_802154_addr
remaining_len -= frag_len;
datagram_offset += frag_len;
/* 2 bytes CRC */
#if LWIP_6LOWPAN_HW_CRC
/* Leave blank, will be filled by HW. */
#else /* LWIP_6LOWPAN_HW_CRC */
/* @todo calculate CRC */
#endif /* LWIP_6LOWPAN_HW_CRC */
/* Calculate frame length */
p_frag->len = p_frag->tot_len = frag_len + 5 + ieee_header_len + 2;
/* 2 bytes CRC */
crc = LWIP_6LOWPAN_DO_CALC_CRC(p_frag->payload, p_frag->len - 2);
pbuf_take_at(p_frag, &crc, 2, p_frag->len - 2);
/* send the packet */
MIB2_STATS_NETIF_ADD(netif, ifoutoctets, p_frag->tot_len);
LWIP_DEBUGF(LOWPAN6_DEBUG | LWIP_DBG_TRACE, ("lowpan6_send: sending packet %p\n", (void *)p));
@ -683,16 +709,13 @@ lowpan6_frag(struct netif *netif, struct pbuf *p, const struct ieee_802154_addr
pbuf_copy_partial(p, buffer + ieee_header_len + lowpan6_header_len, frag_len, 0);
remaining_len = 0;
/* 2 bytes CRC */
#if LWIP_6LOWPAN_HW_CRC
/* Leave blank, will be filled by HW. */
#else /* LWIP_6LOWPAN_HW_CRC */
/* @todo calculate CRC */
#endif /* LWIP_6LOWPAN_HW_CRC */
/* Calculate frame length */
p_frag->len = p_frag->tot_len = frag_len + lowpan6_header_len + ieee_header_len + 2;
/* 2 bytes CRC */
crc = LWIP_6LOWPAN_DO_CALC_CRC(p_frag->payload, p_frag->len - 2);
pbuf_take_at(p_frag, &crc, 2, p_frag->len - 2);
/* send the packet */
MIB2_STATS_NETIF_ADD(netif, ifoutoctets, p_frag->tot_len);
LWIP_DEBUGF(LOWPAN6_DEBUG | LWIP_DBG_TRACE, ("lowpan6_send: sending packet %p\n", (void *)p));