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/* -*- c++ -*- */
/*
* Copyright 2007,2008 Free Software Foundation, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* Double Buffering State Machine
*/
#include "dbsm.h"
#include "memory_map.h"
#include "buffer_pool.h"
#include <stdbool.h>
#include "nonstdio.h"
#include <stdlib.h>
typedef enum {
BS_EMPTY,
BS_FILLING,
BS_FULL,
BS_EMPTYING,
} buffer_state_t;
static buffer_state_t buffer_state[NBUFFERS];
bool
dbsm_nop_inspector(dbsm_t *sm, int buf_this)
{
return false;
}
void
dbsm_init(dbsm_t *sm, int buf0,
const buf_cmd_args_t *recv, const buf_cmd_args_t *send,
inspector_t inspect)
{
if (buf0 & 0x1) // must be even
abort();
sm->buf0 = buf0;
sm->running = false;
sm->recv_args = *recv;
sm->send_args = *send;
sm->rx_idle = true;
sm->tx_idle = true;
sm->inspect = inspect;
// How much to adjust the last_line register.
// It's 1 for everything but the ethernet.
//sm->last_line_adj = recv->port == PORT_ETH ? 3 : 1;
sm->last_line_adj = 1;
buffer_state[sm->buf0] = BS_EMPTY;
buffer_state[sm->buf0 ^ 1] = BS_EMPTY;
sm->precomputed_receive_to_buf_ctrl_word[0] =
(BPC_READ
| BPC_BUFFER(sm->buf0)
| BPC_PORT(sm->recv_args.port)
| BPC_STEP(1)
| BPC_FIRST_LINE(sm->recv_args.first_line)
| BPC_LAST_LINE(sm->recv_args.last_line));
sm->precomputed_receive_to_buf_ctrl_word[1] =
(BPC_READ
| BPC_BUFFER(sm->buf0 ^ 1)
| BPC_PORT(sm->recv_args.port)
| BPC_STEP(1)
| BPC_FIRST_LINE(sm->recv_args.first_line)
| BPC_LAST_LINE(sm->recv_args.last_line));
sm->precomputed_send_from_buf_ctrl_word[0] =
(BPC_WRITE
| BPC_BUFFER(sm->buf0)
| BPC_PORT(sm->send_args.port)
| BPC_STEP(1)
| BPC_FIRST_LINE(sm->send_args.first_line)
| BPC_LAST_LINE(0)); // last line filled in at runtime
sm->precomputed_send_from_buf_ctrl_word[1] =
(BPC_WRITE
| BPC_BUFFER(sm->buf0 ^ 1)
| BPC_PORT(sm->send_args.port)
| BPC_STEP(1)
| BPC_FIRST_LINE(sm->send_args.first_line)
| BPC_LAST_LINE(0)); // last line filled in at runtime
}
static inline void
dbsm_receive_to_buf(dbsm_t *sm, int bufno)
{
buffer_pool_ctrl->ctrl = sm->precomputed_receive_to_buf_ctrl_word[bufno & 1];
}
static inline void
dbsm_send_from_buf(dbsm_t *sm, int bufno)
{
buffer_pool_ctrl->ctrl =
(sm->precomputed_send_from_buf_ctrl_word[bufno & 1]
| BPC_LAST_LINE(buffer_pool_status->last_line[bufno] - sm->last_line_adj));
}
void
dbsm_start(dbsm_t *sm)
{
// printf("dbsm_start: buf0 = %d, recv_port = %d\n", sm->buf0, sm->recv_args.port);
sm->running = true;
buffer_state[sm->buf0] = BS_EMPTY;
buffer_state[sm->buf0 ^ 1] = BS_EMPTY;
bp_clear_buf(sm->buf0);
bp_clear_buf(sm->buf0 ^ 1);
sm->tx_idle = true;
sm->rx_idle = false;
dbsm_receive_to_buf(sm, sm->buf0);
buffer_state[sm->buf0] = BS_FILLING;
}
void
dbsm_stop(dbsm_t *sm)
{
sm->running = false;
bp_clear_buf(sm->buf0);
bp_clear_buf(sm->buf0 ^ 1);
buffer_state[sm->buf0] = BS_EMPTY;
buffer_state[sm->buf0 ^ 1] = BS_EMPTY;
}
static void dbsm_process_helper(dbsm_t *sm, int buf_this);
static void dbsm_error_helper(dbsm_t *sm, int buf_this);
void
dbsm_process_status(dbsm_t *sm, uint32_t status)
{
if (!sm->running)
return;
if (status & (BPS_ERROR(sm->buf0) | BPS_ERROR(sm->buf0 ^ 1))){
putchar('E');
// Most likely an ethernet Rx error. We just restart the transfer.
if (status & (BPS_ERROR(sm->buf0)))
dbsm_error_helper(sm, sm->buf0);
if (status & (BPS_ERROR(sm->buf0 ^ 1)))
dbsm_error_helper(sm, sm->buf0 ^ 1);
}
if (status & BPS_DONE(sm->buf0))
dbsm_process_helper(sm, sm->buf0);
if (status & BPS_DONE(sm->buf0 ^ 1))
dbsm_process_helper(sm, sm->buf0 ^ 1);
}
static void
dbsm_process_helper(dbsm_t *sm, int buf_this)
{
int buf_other = buf_this ^ 1;
bp_clear_buf(buf_this);
if (buffer_state[buf_this] == BS_FILLING){
buffer_state[buf_this] = BS_FULL;
//
// does s/w handle this packet?
//
if (sm->inspect(sm, buf_this)){
// s/w handled the packet; refill the buffer
dbsm_receive_to_buf(sm, buf_this);
buffer_state[buf_this] = BS_FILLING;
}
else { // s/w didn't handle this; pass it on
if(buffer_state[buf_other] == BS_EMPTY){
dbsm_receive_to_buf(sm, buf_other);
buffer_state[buf_other] = BS_FILLING;
}
else
sm->rx_idle = true;
if (sm->tx_idle){
sm->tx_idle = false;
dbsm_send_from_buf(sm, buf_this);
buffer_state[buf_this] = BS_EMPTYING;
}
}
}
else { // buffer was emptying
buffer_state[buf_this] = BS_EMPTY;
if (sm->rx_idle){
sm->rx_idle = false;
dbsm_receive_to_buf(sm, buf_this);
buffer_state[buf_this] = BS_FILLING;
}
if (buffer_state[buf_other] == BS_FULL){
dbsm_send_from_buf(sm, buf_other);
buffer_state[buf_other] = BS_EMPTYING;
}
else
sm->tx_idle = true;
}
}
static void
dbsm_error_helper(dbsm_t *sm, int buf_this)
{
bp_clear_buf(buf_this); // clears ERROR flag
if (buffer_state[buf_this] == BS_FILLING){
dbsm_receive_to_buf(sm, buf_this); // restart the xfer
}
else { // buffer was emptying
dbsm_send_from_buf(sm, buf_this); // restart the xfer
}
}
/*
* Handle DSP Tx underrun
*/
void
dbsm_handle_tx_underrun(dbsm_t *sm)
{
// clear the DSP Tx state machine
sr_tx_ctrl->clear_state = 1;
// If there's a buffer that's empyting, clear it & flush xfer
if (buffer_state[sm->buf0] == BS_EMPTYING){
bp_clear_buf(sm->buf0);
sr_tx_ctrl->clear_state = 1; // flush partial packet
// drop frame in progress on ground. Pretend it finished
dbsm_process_helper(sm, sm->buf0);
}
else if (buffer_state[sm->buf0 ^ 1] == BS_EMPTYING){
bp_clear_buf(sm->buf0 ^ 1);
sr_tx_ctrl->clear_state = 1; // flush partial packet
// drop frame in progress on ground. Pretend it finished
dbsm_process_helper(sm, sm->buf0 ^ 1);
}
}
/*
* Handle DSP Rx overrun
*/
void
dbsm_handle_rx_overrun(dbsm_t *sm)
{
sr_rx_ctrl->clear_overrun = 1;
// If there's a buffer that's filling, clear it.
// Any restart will be the job of the caller.
if (buffer_state[sm->buf0] == BS_FILLING)
bp_clear_buf(sm->buf0);
if (buffer_state[sm->buf0 ^1] == BS_FILLING)
bp_clear_buf(sm->buf0 ^ 1);
}
void
dbsm_wait_for_opening(dbsm_t *sm)
{
if (buffer_state[sm->buf0] == BS_EMPTYING){
// wait for xfer to complete
int mask = BPS_DONE(sm->buf0) | BPS_ERROR(sm->buf0) | BPS_IDLE(sm->buf0);
while ((buffer_pool_status->status & mask) == 0)
;
}
else if (buffer_state[sm->buf0 ^ 1] == BS_EMPTYING){
// wait for xfer to complete
int mask = BPS_DONE(sm->buf0 ^ 1) | BPS_ERROR(sm->buf0 ^ 1) | BPS_IDLE(sm->buf0 ^ 1);
while ((buffer_pool_status->status & mask) == 0)
;
}
}
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