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Decimate more.

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This commit is contained in:
John Greb
2015-05-18 15:18:00 +01:00
parent 95fe79650c
commit f2c1b6e11e
5 changed files with 19 additions and 18 deletions
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plugins/samplesource/v4l-msi/v4lsource.cpp
+13 -12
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@@ -218,6 +218,7 @@ V4LThread::set_tuner_gain(double gain)
return;
}
#define CASTUP (int)(qint16)
int
V4LThread::work(int noutput_items)
{
@@ -230,20 +231,20 @@ V4LThread::work(int noutput_items)
SampleVector::iterator it;
unsigned int pos = 0;
// MSI format is 252 sample pairs : 63 * 4
// MSI format is 252 sample pairs :( 63 * 4) * 4bytes
it = m_convertBuffer.begin();
if (recebuf_len >= 8) { // in bytes
if (recebuf_len >= 16) { // in bytes
b = (uint16_t *) recebuf_ptr;
unsigned int len = 4 * noutput_items; // decimation (i+q * 2 : cmplx)
unsigned int len = 8 * noutput_items; // decimation (i+q * 4 : cmplx)
if (len * 2 > recebuf_len)
len = recebuf_len / 2;
// Decimate by two for lower cpu usage
for (pos = 0; pos < len - 3; pos += 4) {
xreal = (qint16)(b[pos+0]<<2) + (qint16)(b[pos+2]<<2);
// + (qint16)(b[pos+4]<<2) + (qint16)(b[pos+6]<<2);
yimag = (qint16)(b[pos+1]<<2) + (qint16)(b[pos+3]<<2);
// + (int)(b[pos+5]<<2) + (int)(b[pos+7]<<2);
Sample s( (qint16)(xreal >> 2) , (qint16)(yimag>>2) );
for (pos = 0; pos < len - 7; pos += 8) {
xreal = CASTUP(b[pos+0]<<2) + CASTUP(b[pos+2]<<2)
+ CASTUP(b[pos+4]<<2) + CASTUP(b[pos+6]<<2);
yimag = CASTUP(b[pos+1]<<2) + CASTUP(b[pos+3]<<2)
+ CASTUP(b[pos+5]<<2) + CASTUP(b[pos+7]<<2);
Sample s( (qint16)(xreal >> 2) , (qint16)(yimag >> 2) );
*it = s;
it++;
}
@@ -252,8 +253,8 @@ V4LThread::work(int noutput_items)
recebuf_ptr = (void*)(b + pos);
}
// return now if there is still data in buffer, else free buffer and get another.
if (recebuf_len >= 8)
return pos / 4;
if (recebuf_len >= 16)
return pos / 8;
{ // free buffer, if there was one.
if (pos > 0) {
CLEAR(buf);
@@ -290,5 +291,5 @@ V4LThread::work(int noutput_items)
recebuf_len = buf.bytesused;
recebuf_mmap_index = buf.index;
}
return pos / 4;
return pos / 8;
}