unsigned char random_u8(unsigned int seed)
{
rand_t *r;
int rv;
unsigned char rand;
r = rand_open();
if (r == NULL) return -1;
rv = rand_set(r,&seed,4);
if (r == NULL) return -1;
rand = rand_uint8(r);
r = rand_close(r);
return rand;
}
/**
* try send a frame out through the transceiver. the frame should be already placed
* inside buffer.
*
* this function is shared by aloha_send() and aloha_broadcast().
*
* @return
* > 0 success
* 0 failed. no byte has been sent successfully. need call this function to retry.
* - 1: retry reach maximum count. failed the whole sending
*/
uintx _aloha_trysend( TiAloha * mac, char * buf, uint8 len, uint8 option )
{
uintx count=0;
// while (!csma_ischannelclear(mac->rxtx))
// continue;
// attention whether the sending process will wait for ACK or not depends on
// "option" parameter.
count = mac->rxtx->send( mac->rxtx->provider, buf, len, option );
if (count > 0)
{
mac->seqid ++;
mac->retry = 0;
mac->state = ALOHA_STATE_IDLE;
}
else{
if (mac->retry >= CONFIG_ALOHA_MAX_RETRY)
{
mac->retry = 0;
mac->state = ALOHA_STATE_IDLE;
mac->sendfailed ++;
}
else{
mac->retry++;
mac->backoff = CONFIG_ALOHA_MIN_BACKOFF + rand_uint8( mac->backoff << 1 );
if (mac->backoff > CONFIG_ALOHA_MAX_BACKOFF)
mac->backoff = CONFIG_ALOHA_MAX_BACKOFF;
vti_restart( mac->timer, mac->backoff, 0 );
mac->state = ALOHA_STATE_BACKOFF;
}
}
return count;
}
uintx aloha_broadcast( TiAloha * mac, TiFrame * frame, uint8 option )
{
uintx ret=0;
TiIEEE802Frame154Descriptor * desc;
switch (mac->state)
{
case ALOHA_STATE_IDLE:
frame_totalcopyfrom( mac->txbuf, frame );
// according to 802.15.4 specification:
// header 12 B = 1B frame length (required by the transceiver driver currently)
// + 2B frame control + 1B sequence number + 2B destination pan + 2B destination address
// + 2B source pan + 2B source address
//
frame_skipouter( mac->txbuf, 12, 2 );
desc = ieee802frame154_format( &(mac->desc), frame_startptr(frame), frame_capacity(frame), FRAME154_DEF_FRAMECONTROL_DATA_NOACK );
rtl_assert( desc != NULL );
ieee802frame154_set_sequence( desc, mac->seqid );
ieee802frame154_set_panto( desc, mac->panto );
ieee802frame154_set_shortaddrto( desc, FRAME154_BROADCAST_ADDRESS );
ieee802frame154_set_panfrom( desc, mac->panfrom );
ieee802frame154_set_shortaddrfrom( desc, mac->shortaddrfrom );
// char * fcf;
// char * shortaddrto;
// fcf = frame_startptr(frame);
// shortaddrto = (char*)(frame_startptr(frame)) + 3; // todo: according to IEEE 802.15.4 format, 加几？请参考15.4文档确认
// for broadcasting frames, we don't need acknowledgements. so we clear the ACK
// REQUEST bit in the frame control field.
// refer to 802.15.4 protocol format
//
// fcf ++;
// (*fcf) &= 0xFA; // TODO: this value should changed according to 802.15.4 format
// 0xFFFFFFFF the broadcast address according to 802.15.4 protocol format
// attention: we only set the destination short address field to broadcast address.
// the destination pan keeps unchanged.
//
// *shortaddrto ++ = 0xFF;
// *shortaddrto ++ = 0xFF;
//frame_moveinner( mac->txbuf );
mac->sendoption = option;
// standard aloha protocol behavior
#ifdef CONFIG_ALOHA_STANDARD
if (mac->rxtx->ischnclear(mac))
{
_aloha_trysend( mac, frame_startptr(mac->txbuf), frame_capacity(mac->txbuf), option );
}
else{
mac->backoff = rand_uint8( CONFIG_ALOHA_MAX_BACKOFF );
mac->retry = 0;
vti_setinterval( mac->timer, mac->backoff, 0 );
vti_start( mac->timer );
mac->state = ALOHA_STATE_BACKOFF;
}
#endif
// optimized aloha protocol behavior. it will insert a random delay before
// sending to decrease the probability of conflictions.
// wait for a random period before really start the transmission
#ifdef CONFIG_ALOHA_STANDARD
mac->backoff = rand_uint8( CONFIG_ALOHA_MAX_BACKOFF );
mac->retry = 0;
vti_setinterval( mac->timer, mac->backoff, 0 );
vti_start( mac->timer );
mac->state = ALOHA_STATE_BACKOFF;
#endif
ret = frame_capacity( mac->txbuf );
aloha_evolve( mac, NULL );
break;
case ALOHA_STATE_BACKOFF:
// in this state, there's already a frame pending inside the aloha object.
// you have no better choice but wait for this frame to be processed.
//
aloha_evolve( mac, NULL );
ret = 0;
break;
case ALOHA_STATE_SLEEPING:
default:
// currently, this version implementation will ignore any frame sending request
// if the mac component is still in sleeping state. you should wakeup it and
// then retry aloha_send() again.
ret = 0;
break;
}
return ret;
}
uintx aloha_send( TiAloha * mac, TiFrame * frame, uint8 option )
{
TiIEEE802Frame154Descriptor * desc;
uintx ret=0;
switch (mac->state)
{
case ALOHA_STATE_IDLE:
frame_totalcopyfrom( mac->txbuf, frame );
// according to 802.15.4 specification:
// header 12 B = 1B frame length (required by the transceiver driver currently)
// + 2B frame control + 1B sequence number + 2B destination pan + 2B destination address
// + 2B source pan + 2B source address
//
//frame_dump(mac->txbuf);
frame_skipouter( mac->txbuf, 12, 2 );
desc = ieee802frame154_format( &(mac->desc), frame_startptr(mac->txbuf), frame_capacity(mac->txbuf), FRAME154_DEF_FRAMECONTROL_DATA );
rtl_assert( desc != NULL );
ieee802frame154_set_sequence( desc, mac->seqid );
ieee802frame154_set_panto( desc, mac->panto );
ieee802frame154_set_shortaddrto( desc, mac->shortaddrto );
ieee802frame154_set_panfrom( desc, mac->panfrom );
ieee802frame154_set_shortaddrfrom( desc, mac->shortaddrfrom );
//frame_moveinner( mac->txbuf );
mac->sendoption = option;
// standard aloha protocol behavior
#ifdef CONFIG_ALOHA_STANDARD
/*
* @modified by XuFuzhen on 2010.09.29
* - bug fix. should replace frame_length() here with frame_capacity()
*/
if (mac->rxtx->ischnclear(mac))
{
_aloha_trysend( mac, frame_startptr(mac->txbuf), frame_capacity(mac->txbuf), option );
}
else{
mac->backoff = rand_uint8( CONFIG_ALOHA_MAX_BACKOFF );
mac->retry = 0;
vti_setinterval( mac->timer, mac->backoff, 0 );
vti_start( mac->timer );
mac->state = ALOHA_STATE_BACKOFF;
}
#endif
// optimized aloha protocol behavior. it will insert a random delay before
// sending to decrease the probability of conflictions.
// wait for a random period before really start the transmission
#ifndef CONFIG_ALOHA_STANDARD
mac->backoff = rand_uint8( CONFIG_ALOHA_MAX_BACKOFF );
mac->retry = 0;
vti_setinterval( mac->timer, mac->backoff, 0 );
vti_start( mac->timer );
mac->state = ALOHA_STATE_BACKOFF;
#endif
/* @modified by openwsn on 2010.08.30
* - bug fix. you should place the frame_length() call before aloha_evolve()
* because aloha_evolve() may send mac->txbuf and clear it. this will cause
* frame_length() returns 0 instead of the real frame length.
*
* @modified by XuFuzhen on 2010.09.29
* - bug fix. should replace frame_length() here with frame_capacity()
*/
ret = frame_capacity( mac->txbuf );
aloha_evolve( mac, NULL );
break;
case ALOHA_STATE_BACKOFF:
// in this state, there's already a frame pending inside the aloha object.
// you have no better choice but wait for this frame to be processed.
//
aloha_evolve( mac, NULL );
ret = 0;
break;
case ALOHA_STATE_SLEEPING:
default:
// currently, this version implementation will ignore any frame sending request
// if the mac component is still in sleeping state. you should wakeup it and
// then retry aloha_send() again.
ret = 0;
break;
}
return ret;
}
