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/* -*- c++ -*- */
/*
* Copyright 2007 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* GNU Radio 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, or (at your option)
* any later version.
*
* GNU Radio 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, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "gc_jd_queue.h"
#include "mutex_lock.h"
#include "mutex_unlock.h"
extern int gc_sys_tag;
/*
* ea must be 128-byte aligned, the mutex is in the first int32_t, and
* it must be safe to write the remaining 124 bytes with anything at
* all.
*/
static __inline void _fast_mutex_unlock(mutex_ea_t ea)
{
char _tmp[256];
vector signed int *buf
= (vector signed int *) ALIGN(_tmp, 128); // get cache-aligned buffer
buf[0] = spu_splats(0); // the value that unlocks the mutex
mfc_putlluc(buf, ea, 0, 0); // unconditional put, no reservation reqd
spu_readch(MFC_RdAtomicStat);
}
bool
gc_jd_queue_dequeue(gc_eaddr_t q, gc_eaddr_t *item_ea,
int jd_tag, gc_job_desc_t *item)
{
gc_jd_q_links_t local_q;
// Before aquiring the lock, see if it's possible that there's
// something in the queue. Checking in this way makes it easier
// for the PPE to insert things, since we're not contending for
// the lock unless there is something in the queue.
// copy in the queue structure
mfc_get(&local_q, q, sizeof(local_q), gc_sys_tag, 0, 0);
mfc_write_tag_mask(1 << gc_sys_tag); // the tag we're interested in
mfc_read_tag_status_all(); // wait for DMA to complete
if (local_q.head == 0){ // empty
return false;
}
// When we peeked, head was non-zero. Now grab the
// lock and do it for real.
_mutex_lock(q + offsetof(gc_jd_queue_t, m.mutex));
// copy in the queue structure
mfc_get(&local_q, q, sizeof(local_q), gc_sys_tag, 0, 0);
mfc_write_tag_mask(1 << gc_sys_tag); // the tag we're interested in
mfc_read_tag_status_all(); // wait for DMA to complete
if (local_q.head == 0){ // empty
_fast_mutex_unlock(q + offsetof(gc_jd_queue_t, m.mutex));
return false;
}
// copy in job descriptor at head of queue
*item_ea = local_q.head;
// We must use the fence with the jd_tag to ensure that any
// previously initiated put of a job desc is locally ordered before
// the get of the new one.
mfc_getf(item, local_q.head, sizeof(gc_job_desc_t), jd_tag, 0, 0);
mfc_write_tag_mask(1 << jd_tag); // the tag we're interested in
mfc_read_tag_status_all(); // wait for DMA to complete
local_q.head = item->sys.next;
item->sys.next = 0;
if (local_q.head == 0) // now empty?
local_q.tail = 0;
// copy the queue structure back out
mfc_put(&local_q, q, sizeof(local_q), gc_sys_tag, 0, 0);
mfc_write_tag_mask(1 << gc_sys_tag); // the tag we're interested in
mfc_read_tag_status_all(); // wait for DMA to complete
// Q: FIXME do we need to order stores in EA or can we just clear the
// local copy of the mutex above and blast it out, removing the need
// for this explicit unlock?
//
// A: Manual says it's better to use an atomic op rather than
// a normal DMA, and that a putlluc is better than a putllc if
// you can use it.
_fast_mutex_unlock(q + offsetof(gc_jd_queue_t, m.mutex));
return true;
}
void
gc_jd_queue_getllar(gc_eaddr_t q)
{
// get reservation that includes the flag in the queue
gc_eaddr_t ea = q + offsetof(gc_jd_queue_t, f.flag);
char _tmp[256];
char *buf = (char *) ALIGN(_tmp, 128); // get cache-aligned buffer
mfc_getllar(buf, ALIGN128_EA(ea), 0, 0);
spu_readch(MFC_RdAtomicStat);
}
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