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[media] Speed up DVB TS stream delivery from DMA buffer into dvb-core's buffer

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Avoid unnecessary DVB TS 188 sized packet copying from DMA buffer into stack.
Backtrack one 188 sized packet just after some garbage bytes when possible.
This obsoletes patch https://patchwork.kernel.org/patch/118147/

Signed-off-by: Marko Ristola <marko.ristola@kolumbus.fi>
Acked-by: Andreas Oberritter <obi@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Marko Ristola 2011-04-08 12:40:51 -03:00 committed by Mauro Carvalho Chehab
parent 3f84a4e1c1
commit 38e009aac9
1 changed files with 60 additions and 63 deletions
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123
drivers/media/dvb/dvb-core/dvb_demux.c
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@ -478,97 +478,94 @@ void dvb_dmx_swfilter_packets(struct dvb_demux *demux, const u8 *buf,
EXPORT_SYMBOL(dvb_dmx_swfilter_packets);
void dvb_dmx_swfilter(struct dvb_demux *demux, const u8 *buf, size_t count)
static inline int find_next_packet(const u8 *buf, int pos, size_t count,
const int pktsize)
{
int start = pos, lost;
while (pos < count) {
if (buf[pos] == 0x47 ||
(pktsize == 204 && buf[pos] == 0xB8))
break;
pos++;
}
lost = pos - start;
if (lost) {
/* This garbage is part of a valid packet? */
int backtrack = pos - pktsize;
if (backtrack >= 0 && (buf[backtrack] == 0x47 ||
(pktsize == 204 && buf[backtrack] == 0xB8)))
return backtrack;
}
return pos;
}
/* Filter all pktsize= 188 or 204 sized packets and skip garbage. */
static inline void _dvb_dmx_swfilter(struct dvb_demux *demux, const u8 *buf,
size_t count, const int pktsize)
{
int p = 0, i, j;
const u8 *q;
spin_lock(&demux->lock);
if (demux->tsbufp) {
if (demux->tsbufp) { /* tsbuf[0] is now 0x47. */
i = demux->tsbufp;
j = 188 - i;
j = pktsize - i;
if (count < j) {
memcpy(&demux->tsbuf[i], buf, count);
demux->tsbufp += count;
goto bailout;
}
memcpy(&demux->tsbuf[i], buf, j);
if (demux->tsbuf[0] == 0x47)
if (demux->tsbuf[0] == 0x47) /* double check */
dvb_dmx_swfilter_packet(demux, demux->tsbuf);
demux->tsbufp = 0;
p += j;
}
while (p < count) {
if (buf[p] == 0x47) {
if (count - p >= 188) {
dvb_dmx_swfilter_packet(demux, &buf[p]);
p += 188;
} else {
i = count - p;
memcpy(demux->tsbuf, &buf[p], i);
demux->tsbufp = i;
goto bailout;
}
} else
p++;
while (1) {
p = find_next_packet(buf, p, count, pktsize);
if (p >= count)
break;
if (count - p < pktsize)
break;
q = &buf[p];
if (pktsize == 204 && (*q == 0xB8)) {
memcpy(demux->tsbuf, q, 188);
demux->tsbuf[0] = 0x47;
q = demux->tsbuf;
}
dvb_dmx_swfilter_packet(demux, q);
p += pktsize;
}
i = count - p;
if (i) {
memcpy(demux->tsbuf, &buf[p], i);
demux->tsbufp = i;
if (pktsize == 204 && demux->tsbuf[0] == 0xB8)
demux->tsbuf[0] = 0x47;
}
bailout:
spin_unlock(&demux->lock);
}
void dvb_dmx_swfilter(struct dvb_demux *demux, const u8 *buf, size_t count)
{
_dvb_dmx_swfilter(demux, buf, count, 188);
}
EXPORT_SYMBOL(dvb_dmx_swfilter);
void dvb_dmx_swfilter_204(struct dvb_demux *demux, const u8 *buf, size_t count)
{
int p = 0, i, j;
u8 tmppack[188];
spin_lock(&demux->lock);
if (demux->tsbufp) {
i = demux->tsbufp;
j = 204 - i;
if (count < j) {
memcpy(&demux->tsbuf[i], buf, count);
demux->tsbufp += count;
goto bailout;
}
memcpy(&demux->tsbuf[i], buf, j);
if ((demux->tsbuf[0] == 0x47) || (demux->tsbuf[0] == 0xB8)) {
memcpy(tmppack, demux->tsbuf, 188);
if (tmppack[0] == 0xB8)
tmppack[0] = 0x47;
dvb_dmx_swfilter_packet(demux, tmppack);
}
demux->tsbufp = 0;
p += j;
}
while (p < count) {
if ((buf[p] == 0x47) || (buf[p] == 0xB8)) {
if (count - p >= 204) {
memcpy(tmppack, &buf[p], 188);
if (tmppack[0] == 0xB8)
tmppack[0] = 0x47;
dvb_dmx_swfilter_packet(demux, tmppack);
p += 204;
} else {
i = count - p;
memcpy(demux->tsbuf, &buf[p], i);
demux->tsbufp = i;
goto bailout;
}
} else {
p++;
}
}
bailout:
spin_unlock(&demux->lock);
_dvb_dmx_swfilter(demux, buf, count, 204);
}
EXPORT_SYMBOL(dvb_dmx_swfilter_204);
static struct dvb_demux_filter *dvb_dmx_filter_alloc(struct dvb_demux *demux)