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path: root/cesar/mac/pbproc/src/fsm_rx_data.c
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/* Cesar project {{{
 *
 * Copyright (C) 2007 Spidcom
 *
 * <<<Licence>>>
 *
 * }}} */
/**
 * \file    mac/pbproc/src/fsm_rx_data.c
 * \brief   FSM RX data part.
 * \ingroup mac_pbproc
 */
#include "common/std.h"

#include "hal/gpio/gpio.h"

#include "inc/context.h"
#include "inc/fc.h"
#include "inc/fsm_rx_data.h"
#include "inc/fsm_handle_fc.h"
#include "inc/fsm_top.h"

#include "hal/phy/pbdma.h"

/**
 * Restart VCS for next MPDU and go to next state.
 * \param  ctx  pbproc context
 */
static void
pbproc_frda_next (pbproc_t *ctx);

/**
 * Anticipate SACK sending for hybrid mode.
 * \param  ctx  pbproc context
 */
static void
pbproc_frda_send_sack_anticip (pbproc_t *ctx);

/**
 * Send SACK from current SACKD.
 * \param  ctx  pbproc context
 */
static void
pbproc_frda_send_sack (pbproc_t *ctx);

/**
 * Initialise SACKD, reset if not part of last burst.
 * \param  ctx  pbproc context
 * \param  sof  received MPDU SOF
 */
static void
pbproc_frda_sackd_init (pbproc_t *ctx, const pbproc_fc_sof_t *sof);

/**
 * Give up reception and eventually prepare a SACK to signal the problem.
 * \param  ctx  pbproc context
 * \param  rx_date  start of preamble date
 * \param  sof  SOF FC
 * \param  wack  with acknowledge
 * \param  sacki_uniform  uniform SACK information
 *
 * Go to next FSM state.
 */
static void
pbproc_frda_error (pbproc_t *ctx, u32 rx_date, const pbproc_fc_sof_t *sof,
                   bool wack, uint sacki_uniform);

/**
 * Unchain received PB, and give them to the upper layer.
 * \param  ctx  pbproc context
 */
static void
pbproc_frda_commit (pbproc_t *ctx);

void
pbproc_frda_init (pbproc_t *ctx)
{
    dbg_assert (ctx);
    ctx->fsm.states[PBPROC_FSM_STATE_RX_DATA_WACK].pbdma_cb =
        pbproc_frda__rx_data_wack__pbdma;
    ctx->fsm.states[PBPROC_FSM_STATE_RX_DATA_WACK_LAST_PB].pbdma_cb =
        pbproc_frda__rx_data_wack_last_pb__pbdma;
    ctx->fsm.states[PBPROC_FSM_STATE_RX_DATA_WOACK].pbdma_cb =
        pbproc_frda__rx_data_woack__pbdma;
    ctx->fsm.states[PBPROC_FSM_STATE_RX_BURST].rx_fc_cb =
        pbproc_frda__rx_burst__rx_fc;
    ctx->fsm.states[PBPROC_FSM_STATE_RX_BURST].access_cb =
        pbproc_frda__rx_burst__access;
}

void ARCH_ILRAM
pbproc_frda__handle (pbproc_t *ctx, u32 rx_date, const pbproc_fc_sof_t *sof)
{
    bool wack, unassociated;
    dbg_claim (ctx);
    dbg_claim (sof);
    /* TODO features. */
    dbg_claim (sof->pbsz == false);
    dbg_claim (sof->num_sym != 0);
    dbg_claim (sof->bbf == false);
    dbg_claim (sof->dcppcf == false);
    dbg_claim (sof->rsr == false);
    /* Update stats. */
    ctx->stats.rx_data++;
    /* Unassociated? */
    unassociated = sof->stei == 0 || sof->mnbf;
    /* With ACK? */
    wack = sof->snid == ctx->alloc.snid && sof->dtei == ctx->config->tei;
    /* Ignore frames ending after the allocation. */
    uint fl_tck = MAC_FL_TO_TCK (sof->fl_av);
    if (less_mod2p32 (ctx->alloc.end_date,
                      rx_date + 2 * ctx->times.pre_fcs_tck + fl_tck
                      + MAC_CIFS_TCK))
    {
        ctx->stats.rx_out_of_alloc++;
        pbproc_frda_error (ctx, rx_date, sof, false,
                           PBPROC_FC_SACKI_UNIFORM_ALL_ERROR);
        return;
    }
    /* Burst? */
    ctx->recv_mpdu.mpdu_cnt = sof->mpdu_cnt;
    /* Get tonemap. */
    uint tmi = sof->tmi_av;
    tonemap_t *tm;
    uint rifs_tck;
    if (tmi < PHY_MOD_ROBO_NB)
    {
        tm = &ctx->config->tonemask_info.tonemap_robo[tmi];
        rifs_tck = MAC_RIFS_DEFAULT_TCK;
    }
    else if (sof->mcf || unassociated)
    {
        pbproc_frda_error (ctx, rx_date, sof, wack,
                           PBPROC_FC_SACKI_UNIFORM_TMI_DEFAULT_ROBO);
        return;
    }
    else
    {
        dbg_claim (wack);
        dbg_claim (tmi < TONEMAP_INDEX_NB);
        sta_t *sta = mac_store_sta_get (ctx->store, sof->stei);
        if (sta)
        {
            tm = sta->rx_tonemaps->tm[tmi];
            blk_release (sta);
            rifs_tck = MAC_RIFS_SPC_ANY_TCK;
            if (!tm)
            {
                pbproc_frda_error (ctx, rx_date, sof, true,
                                   PBPROC_FC_SACKI_UNIFORM_TMI_RESTART);
                return;
            }
        }
        else
        {
            pbproc_frda_error (ctx, rx_date, sof, true,
                               PBPROC_FC_SACKI_UNIFORM_TMI_RESTART);
            return;
        }
    }
    /* Use BIFS for bursts. */
    if (ctx->recv_mpdu.mpdu_cnt)
        rifs_tck = MAC_BIFS_TCK;
    /* Compute symbol and PB number. */
    uint symb_nb;
    if (sof->num_sym == 1)
        symb_nb = 1;
    else if (sof->num_sym == 2)
        symb_nb = 2;
    else
        symb_nb = ((fl_tck - rifs_tck - 2 * MAC_DX567_TCK)
                   / ctx->symbol_tck[tm->gil] + 2);
    uint bits_per_pb = tm->bits_per_pb[PHY_PB_SIZE_520];
    /* To take into account that there is only one segment in the last
     * symbol, here is the trick: */
    uint pb_nb = ((symb_nb - 1) * tm->bits_per_symbol + bits_per_pb)
        / bits_per_pb;
    /* Prepare decryption key. */
    bool bypass_aes = true;
    u32 *key = NULL;
    bool nek_ok = false;
    do
    {
        if (sof->eks < MAC_EKS_NB)
        {
            if (unassociated)
                break;
            sta_t *sta = mac_store_sta_get (ctx->store, sof->stei);
            mac_nek_t (*nek)[2];
            if (sta)
            {
                nek = sta->nek;
                blk_release (sta);
                if (!nek)
                    nek = &ctx->config->nek;
            }
            else
                nek = &ctx->config->nek;
            if ((*nek)[0].eks == sof->eks)
                key = (*nek)[0].nek_dec;
            else if ((*nek)[1].eks == sof->eks)
                key = (*nek)[1].nek_dec;
            else
                break;
            bypass_aes = false;
            nek_ok = true;
        }
        else if (sof->eks == MAC_EKS_CLEAR)
        {
            nek_ok = true;
        }
    } while (0);
    /* Acknowledge multicast frame even if it can not be decrypted. */
    if (!nek_ok && !(wack && sof->mcf))
    {
        pbproc_frda_error (ctx, rx_date, sof, wack,
                           PBPROC_FC_SACKI_UNIFORM_NEK_ERROR);
        return;
    }
    /* Check for PB Pool shortage. */
    if (ctx->rx_pool_size < 1 + ctx->chandata_nb + pb_nb)
    {
        ctx->stats.rx_pool_shortage++;
        pbproc_frda_error (ctx, rx_date, sof, wack,
                           PBPROC_FC_SACKI_UNIFORM_ALL_ERROR);
        return;
    }
    /* First thing to do: unblock the hardware. */
    if (tmi >= PHY_MOD_ROBO_NB)
        phy_set_tonemap (ctx->phy, tm->tmdma_desc_head);
    phy_rx_prepare (ctx->phy, pb_nb, tm->phy_combo_params[PHY_PB_SIZE_520],
                    tm->gil, symb_nb, tm->tcc_halfit);
    /* Save received MPDU parameters. */
    ctx->recv_mpdu.rx_params.preamble_ntb = rx_date
        + ctx->config->ntb_offset_tck;
    ctx->recv_mpdu.rx_params.tei = sof->stei;
    ctx->recv_mpdu.rx_params.lid = sof->lid;
    ctx->recv_mpdu.rx_params.snid = sof->snid;
    ctx->recv_mpdu.rx_params.bcast = sof->mcf;
    ctx->recv_mpdu.rx_params.cfp = sof->cfs;
    ctx->recv_mpdu.rx_params.multi_net_bcast = sof->mnbf;
    ctx->recv_mpdu.rx_params.sound = false;
    ctx->recv_mpdu.rx_params.eks = sof->eks;
    ctx->recv_mpdu.rx_params.pending_seg_nb = sof->ppb;
    ctx->recv_mpdu.rx_params.ble = sof->ble;
    ctx->recv_mpdu.rx_params.pb_size = PHY_PB_SIZE_520;
    ctx->recv_mpdu.rx_params.tmi_av = sof->tmi_av;
    ctx->recv_mpdu.rx_params.mpdu_cnt = sof->mpdu_cnt;
    ctx->recv_mpdu.rx_params.bdf = sof->bdf;
    ctx->recv_mpdu.rx_params.hp10df = sof->hp10df;
    ctx->recv_mpdu.rx_params.hp11df = sof->hp11df;
    ctx->recv_mpdu.rx_params.mfs_cmd_data = sof->mfs_cmd_data;
    ctx->recv_mpdu.rx_params.mfs_cmd_mme = sof->mfs_cmd_mgmt;
    ctx->recv_mpdu.pb_nb = pb_nb;
    ctx->recv_mpdu.ack_date = rx_date + ctx->times.pre_fcs_tck + fl_tck;
    ctx->recv_mpdu.drop = !nek_ok;
    /* Keep a block to store received MPDU parameters. */
    pb_t *pool = ctx->rx_pool_head;
    ctx->recv_mpdu.rx_desc = (pbproc_rx_desc_t *) pool;
    pool = pool->next;
    /* Prepare channel data blocks and give them to PB DMA. */
    if (ctx->chandata_nb && nek_ok && !unassociated)
    {
        uint i;
        /* Take from RX pool. */
        ctx->recv_mpdu.chandata_head = pool;
        ctx->recv_mpdu.chandata_nb = ctx->chandata_nb;
        /* Fill configuration. */
        for (i = 0; i < ctx->chandata_nb; i++)
        {
            pool->phy_pb.chandata.conf = ctx->chandata_conf[i];
            pool = pool->next;
        }
    }
    else
    {
        ctx->recv_mpdu.chandata_head = NULL;
        ctx->recv_mpdu.chandata_nb = 0;
    }
    /* If there is more than a few PB, program next access using PB DMA before
     * last symbol reception to prepare SACKD. */
    bool sack_last_pb = wack && pb_nb > PBPROC_SACKD_ANTICIP_PB_THRESHOLD;
    uint pb_it;
    if (sack_last_pb)
        pb_it = pb_nb - PBPROC_SACKD_ANTICIP_PB_NB;
    else if (ctx->recv_mpdu.chandata_nb)
        pb_it = 0;
    else
        pb_it = pb_nb;
    ctx->recv_mpdu.pb_head = pool;
    phy_pbdma_start (ctx->phy, bypass_aes, key, pb_nb, pb_nb, pb_it,
                     &pool->phy_pb,
                     &ctx->recv_mpdu.chandata_head->phy_pb.chandata, true);
    if (wack)
    {
        /* Initialise SACKD. */
        pbproc_frda_sackd_init (ctx, sof);
        /* Wait. */
        pbproc_fsm_change_state (ctx, sack_last_pb
                                 ? PBPROC_FSM_STATE_RX_DATA_WACK
                                 : PBPROC_FSM_STATE_RX_DATA_WACK_LAST_PB);
        ctx->stats.rx_data_wack++;
    }
    else
    {
        /* Wait end of frame. */
        pbproc_fsm_change_state (ctx, PBPROC_FSM_STATE_RX_DATA_WOACK);
        ctx->stats.rx_data_woack++;
    }
    /* Signal received traffic. */
    GPIO_SET (LED_TRAFFIC, 1);
}

void ARCH_ILRAM
pbproc_frda__rx_data_wack__pbdma (pbproc_t *ctx)
{
    dbg_claim (ctx);
    /* Prepare SACKD. */
    ctx->recv_mpdu.sackd.any_pb_crc_error =
        ctx->recv_mpdu.sackd.any_pb_crc_error
        || ctx->pbdma_status.pb_crc_error;
    pbproc_sacki_enc_process (&ctx->recv_mpdu.sackd.sacki_enc,
                              phy_pbdma_get_crc_bitmap (ctx->phy),
                              ctx->recv_mpdu.pb_nb -
                              PBPROC_SACKD_ANTICIP_PB_NB, false);
    /* Program next access using PB DMA after last PB reception. */
    uint pb_nb = ctx->recv_mpdu.pb_nb;
    phy_pbdma_update (ctx->phy, pb_nb,
                      ctx->recv_mpdu.chandata_nb ? 0 : pb_nb);
    pbproc_fsm_change_state (ctx, PBPROC_FSM_STATE_RX_DATA_WACK_LAST_PB);
}

void ARCH_ILRAM
pbproc_frda__rx_data_wack_last_pb__pbdma (pbproc_t *ctx)
{
    dbg_claim (ctx);
    /* Prepare FC 1.0 in advance. */
    if (ctx->recv_mpdu.mpdu_cnt == 0)
        pbproc_frda_send_sack_anticip (ctx);
    /* Prepare SACKD. */
    ctx->recv_mpdu.sackd.any_pb_crc_error =
        ctx->recv_mpdu.sackd.any_pb_crc_error
        || ctx->pbdma_status.pb_crc_error;
    if (!ctx->recv_mpdu.sackd.any_pb_crc_error)
    {
        /* All OK, use uniform encoding. */
        ctx->recv_mpdu.sackd.sackt[ctx->recv_mpdu.mpdu_cnt] =
            PBPROC_FC_SACKT_UNIFORM;
        pbproc_sacki_enc_rewind (&ctx->recv_mpdu.sackd.sacki_enc);
        u32 code = PBPROC_FC_SACKI_UNIFORM_ALL_OK;
        pbproc_sacki_enc_copy (&ctx->recv_mpdu.sackd.sacki_enc, &code,
                               PBPROC_FC_SACKI_UNIFORM_SIZE);
        PBPROC_TRACE (FRDA_SACK_UNIFORM, code);
    }
    else
    {
        /* Finish compression to determine smallest SACKD. */
        const volatile u32 *crc_bmp = phy_pbdma_get_crc_bitmap (ctx->phy);
        pbproc_sacki_enc_process (&ctx->recv_mpdu.sackd.sacki_enc, crc_bmp,
                                  ctx->recv_mpdu.pb_nb, true);
        if (pbproc_sacki_enc_better (&ctx->recv_mpdu.sackd.sacki_enc,
                                     ctx->recv_mpdu.pb_nb))
        {
            /* Compressed is better. */
            ctx->recv_mpdu.sackd.sackt[ctx->recv_mpdu.mpdu_cnt] =
                PBPROC_FC_SACKT_MIXED_COMPRESSED;
            PBPROC_TRACE (FRDA_SACK_MIXED_COMPRESSED);
        }
        else
        {
            /* Non compressed is better. */
            ctx->recv_mpdu.sackd.sackt[ctx->recv_mpdu.mpdu_cnt] =
                PBPROC_FC_SACKT_MIXED;
            pbproc_sacki_enc_rewind (&ctx->recv_mpdu.sackd.sacki_enc);
            pbproc_sacki_enc_copy (&ctx->recv_mpdu.sackd.sacki_enc, crc_bmp,
                                   ctx->recv_mpdu.pb_nb);
            PBPROC_TRACE (FRDA_SACK_MIXED);
        }
    }
    /* TODO: Handle bidir. */
    /* Send SACK if not a burst MPDU. */
    if (ctx->recv_mpdu.mpdu_cnt == 0)
        pbproc_frda_send_sack (ctx);
    /* Unchain and give received frame to upper layer. */
    pbproc_frda_commit (ctx);
    /* Prepare for next. */
    pbproc_frda_next (ctx);
}

void ARCH_ILRAM
pbproc_frda__rx_data_woack__pbdma (pbproc_t *ctx)
{
    dbg_claim (ctx);
    /* Unchain and give received frame to upper layer. */
    pbproc_frda_commit (ctx);
    /* Prepare for next. */
    pbproc_frda_next (ctx);
}

static void ARCH_ILRAM
pbproc_frda_commit (pbproc_t *ctx)
{
    dbg_claim (ctx);
    if (!ctx->recv_mpdu.drop)
    {
        pbproc_rx_desc_t *rx = ctx->recv_mpdu.rx_desc;
        /* Unchain used PB. */
        pb_t *tail = PARENT_OF (pb_t, phy_pb, phy_pbdma_get_tail (ctx->phy));
        slist_slice (ctx->rx_pool_, tail, 1 + ctx->recv_mpdu.chandata_nb
                     + ctx->recv_mpdu.pb_nb, paste_size);
        ctx->recv_mpdu.pb_tail = tail;
        /* Received frame is given to upper layer in DSR. */
        rx->rx->params = ctx->recv_mpdu.rx_params;
        rx->rx->mfs = NULL;
        rx->rx->mfs_mme = NULL;
        rx->rx->pb_first = ctx->recv_mpdu.pb_head;
        rx->rx->pb_last = ctx->recv_mpdu.pb_tail;
        rx->rx->pb_nb = ctx->recv_mpdu.pb_nb;
        rx->rx->chandata_first = ctx->recv_mpdu.chandata_head;
        rx->rx->chandata_nb = ctx->recv_mpdu.chandata_nb;
        slist_push_back (ctx->commit.rx_, rx);
        pbproc_fsm_schedule_deferred (ctx);
    }
    dbg_invalid_ptr (ctx->recv_mpdu.pb_head);
    dbg_invalid_ptr (ctx->recv_mpdu.pb_tail);
    dbg_invalid_ptr (ctx->recv_mpdu.chandata_head);
}

void ARCH_ILRAM
pbproc_frda__rx_burst__rx_fc (pbproc_t *ctx, u32 rx_date,
                              const pbproc_fc_t *fc_av)
{
    dbg_claim (ctx);
    /* Easy... */
    pbproc_fhfc_handle_fc (ctx, rx_date, fc_av);
}

void ARCH_ILRAM
pbproc_frda__rx_burst__access (pbproc_t *ctx)
{
    dbg_claim (ctx);
    /* Handle access. */
    pbproc_ftop__idle__access (ctx);
    /* Update stats. */
    ctx->stats.rx_data_burst_stop++;
}

static void ARCH_ILRAM
pbproc_frda_sackd_init (pbproc_t *ctx, const pbproc_fc_sof_t *sof)
{
    dbg_claim (ctx);
    dbg_claim (sof);
    /* Clear current SACKD if this frame is not part of the previous burst. */
    bool reinit = false;
    pbproc_sackd_t *sackd = &ctx->recv_mpdu.sackd;
    if (!sackd->valid
        || sackd->tei != sof->stei
        || sackd->lid != sof->lid
        || sackd->bcast != sof->mcf
        || sackd->burst_cnt != sof->burst_cnt
        || sackd->last_mpdu_cnt <= sof->mpdu_cnt)
    {
        sackd->sackt[0] = PBPROC_FC_SACKT_NOT_RECEIVED;
        sackd->sackt[1] = PBPROC_FC_SACKT_NOT_RECEIVED;
        sackd->sackt[2] = PBPROC_FC_SACKT_NOT_RECEIVED;
        sackd->sackt[3] = PBPROC_FC_SACKT_NOT_RECEIVED;
        reinit = true;
    }
    /* Record SACKD parameters. */
    sackd->valid = true;
    sackd->tei = sof->stei;
    sackd->lid = sof->lid;
    sackd->bcast = sof->mcf;
    sackd->cfp = sof->cfs;
    sackd->burst_cnt = sof->burst_cnt;
    sackd->last_mpdu_cnt = sof->mpdu_cnt;
    /* Initialise SACKD preparation. */
    sackd->any_pb_crc_error = false;
    pbproc_sacki_enc_init (&sackd->sacki_enc,
                           PBPROC_FC_SACK_SACKI_BITS
                           - (MAC_LID_IS_PLID (sof->lid) ? 4 : 0),
                           reinit);
}

static void ARCH_ILRAM
pbproc_frda_error (pbproc_t *ctx, u32 rx_date, const pbproc_fc_sof_t *sof,
                   bool wack, uint sacki_uniform)
{
    dbg_claim (ctx);
    dbg_claim (sof);
    dbg_claim (sacki_uniform < PBPROC_FC_SACKI_UNIFORM_NB);
    /* First thing to do: unblock the hardware. */
    phy_rx_prepare_short (ctx->phy);
    /* ACK date. */
    ctx->recv_mpdu.ack_date = rx_date + ctx->times.pre_fcs_tck
        + MAC_FL_TO_TCK (sof->fl_av);
    /* With acknowledge? */
    if (wack)
    {
        /* Prepare SACKD. */
        pbproc_frda_sackd_init (ctx, sof);
        ctx->recv_mpdu.sackd.sackt[ctx->recv_mpdu.mpdu_cnt] =
            PBPROC_FC_SACKT_UNIFORM;
        pbproc_sacki_enc_copy (&ctx->recv_mpdu.sackd.sacki_enc,
                               &sacki_uniform, PBPROC_FC_SACKI_UNIFORM_SIZE);
        PBPROC_TRACE (FRDA_SACK_UNIFORM, sacki_uniform);
        /* Send SACK if not a burst MPDU. */
        if (ctx->recv_mpdu.mpdu_cnt == 0)
        {
            pbproc_frda_send_sack_anticip (ctx);
            pbproc_frda_send_sack (ctx);
        }
    }
    /* Prepare for next. */
    pbproc_frda_next (ctx);
    /* Update stats. */
    ctx->stats.rx_data_error++;
}

static void ARCH_ILRAM
pbproc_frda_send_sack_anticip (pbproc_t *ctx)
{
    dbg_claim (ctx);
    if (ctx->alloc.hybrid)
        phy_tx_fc10 (ctx->phy, ctx->recv_mpdu.ack_date, 0);
}

static void ARCH_ILRAM
pbproc_frda_send_sack (pbproc_t *ctx)
{
    dbg_claim (ctx);
    dbg_claim (ctx->recv_mpdu.sackd.valid);
    /* SACK FC. */
    pbproc_fc_t fc;
    fc.words[0] = BF_FILL (
        PBPROC_FC_SACK_W0,
        (DT_AV, PBPROC_FC_DT_SACK),
        (ACCESS, false),
        (SNID, ctx->alloc.snid),
        (DTEI, ctx->recv_mpdu.sackd.tei),
        (CFS, ctx->recv_mpdu.sackd.cfp),
        (BDF, false), /* TODO */
        (SVN, 0),
        (RRTF, 0),
        (MFS_RSP_DATA, MFS_FSM_RSP_ACK),
        (MFS_RSP_MGMT, MFS_FSM_RSP_ACK),
        (SACKT3, ctx->recv_mpdu.sackd.sackt[3]),
        (SACKT2, ctx->recv_mpdu.sackd.sackt[2]),
        (SACKT1, ctx->recv_mpdu.sackd.sackt[1]),
        (SACKT0, ctx->recv_mpdu.sackd.sackt[0]));
    fc.words[1] = BF_FILL (
        PBPROC_FC_SACK_W1,
        (SACKI0, ctx->recv_mpdu.sackd.sacki_enc.si[0]));
    fc.words[2] = BF_FILL (
        PBPROC_FC_SACK_W2,
        (SACKI1, ctx->recv_mpdu.sackd.sacki_enc.si[1]));
    fc.words[3] = BF_FILL (
        PBPROC_FC_SACK_W3,
        (SACKI2, ctx->recv_mpdu.sackd.sacki_enc.si[2]));
    /* RX window size. */
    if (MAC_LID_IS_PLID (ctx->recv_mpdu.sackd.lid))
    {
        u8 window_size_encoded = MFS_RX_WINDOW_SIZE_DATA_DEFAULT_ENCODED;
        mfs_rx_t *mfs = NULL;
        if (ctx->recv_mpdu.sackd.tei)
            mfs = mac_store_mfs_get_rx (ctx->store,
                                        ctx->recv_mpdu.sackd.bcast, false,
                                        ctx->recv_mpdu.sackd.lid,
                                        ctx->recv_mpdu.sackd.tei);
        if (mfs)
        {
            window_size_encoded = mfs->window_size_encoded;
            blk_release (mfs);
        }
        fc.words[3] |= BF_SHIFT (PBPROC_FC_SACK_W3__RXWSZ_NO_RRTL,
                                 window_size_encoded);
    }
    /* Send it. */
    phy_tx_param_short (ctx->phy,
                        PHY_FC_MODE (ctx->alloc.hybrid,
                                     ctx->config->fc_symbols_nb));
    phy_tx_frame (ctx->phy, ctx->recv_mpdu.ack_date, false, false, fc.words);
    /* Ensure SACKD will be cleared. */
    /* TODO: keep it for RSR. */
    ctx->recv_mpdu.sackd.valid = false;
}

static void ARCH_ILRAM
pbproc_frda_next (pbproc_t *ctx)
{
    dbg_claim (ctx);
    /* Burst? */
    if (ctx->recv_mpdu.mpdu_cnt == 0)
    {
        /* Prepare for next MPDU. */
        ca_access_vcs_restart (ctx->ca, ctx->recv_mpdu.ack_date,
                               ctx->times.pre_fcs_tck + MAC_CIFS_TCK,
                               PBPROC_ANTICIP_TCK, false);
        pbproc_fsm_change_state (ctx, PBPROC_FSM_STATE_IDLE);
    }
    else
    {
        /* Wait for next MPDU part of the burst. */
        ca_access_vcs_restart (ctx->ca, ctx->recv_mpdu.ack_date,
                               ctx->times.eifs_tck,
                               PBPROC_ANTICIP_TCK, true);
        phy_rx_activate (ctx->phy, false, ctx->recv_mpdu.ack_date, true);
        pbproc_fsm_change_state (ctx, PBPROC_FSM_STATE_RX_BURST);
    }
}