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Revert "Rework YSF AMBE repetition FEC." 

This reverts commit 17b9e7e287.
This commit is contained in:
Jonathan Naylor 2016-11-22 21:51:40 +00:00
parent f364eda0a4
commit fee3cf561c
2 changed files with 45 additions and 66 deletions
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109
YSFPayload.cpp
View File

@ -393,11 +393,51 @@ unsigned int CYSFPayload::processVDMode2Audio(unsigned char* data)
data += YSF_SYNC_LENGTH_BYTES + YSF_FICH_LENGTH_BYTES;
unsigned int errors = 0U;
errors += processVDMode2AudioBlock(data + 5U);
errors += processVDMode2AudioBlock(data + 23U);
errors += processVDMode2AudioBlock(data + 41U);
errors += processVDMode2AudioBlock(data + 59U);
errors += processVDMode2AudioBlock(data + 77U);
unsigned int offset = 40U; // DCH(0)
// We have a total of 5 VCH sections, iterate through each
for (unsigned int j = 0U; j < 5U; j++, offset += 144U) {
unsigned char vch[13U];
// Deinterleave
for (unsigned int i = 0U; i < 104U; i++) {
unsigned int n = INTERLEAVE_TABLE_26_4[i];
bool s = READ_BIT1(data, offset + n) != 0x00U;
WRITE_BIT1(vch, i, s);
}
// "Un-whiten" (descramble)
for (unsigned int i = 0U; i < 13U; i++)
vch[i] ^= WHITENING_DATA[i];
// errors += READ_BIT1(vch, 103); // Padding bit must be zero but apparently it is not...
for (unsigned int i = 0U; i < 81U; i += 3) {
uint8_t vote = bool(READ_BIT1(vch, i)) + bool(READ_BIT1(vch, i + 1)) + bool(READ_BIT1(vch, i + 2));
if (vote == 1 || vote == 2) {
bool decision = vote / 2; // exploit integer division: 1/2 == 0, 2/2 == 1.
WRITE_BIT1(vch, i, decision);
WRITE_BIT1(vch, i + 1, decision);
WRITE_BIT1(vch, i + 2, decision);
errors++;
}
}
// Reconstruct only if we have bit errors. Technically we could even
// constrain it individually to the 5 VCH sections.
if (errors > 0U) {
// Scramble
for (unsigned int i = 0U; i < 13U; i++)
vch[i] ^= WHITENING_DATA[i];
// Interleave
for (unsigned int i = 0U; i < 104U; i++) {
unsigned int n = INTERLEAVE_TABLE_26_4[i];
bool s = READ_BIT1(vch, i);
WRITE_BIT1(data, offset + n, s);
}
}
}
// "errors" is the number of triplets that were recognized to be corrupted
// and that were corrected. There are 27 of those per VCH and 5 VCH per CC,
@ -407,65 +447,6 @@ unsigned int CYSFPayload::processVDMode2Audio(unsigned char* data)
return errors;
}
unsigned int CYSFPayload::processVDMode2AudioBlock(unsigned char* data)
{
assert(data != NULL);
unsigned int errors = 0U;
unsigned char vch[13U];
// Deinterleave
for (unsigned int i = 0U; i < 104U; i++) {
unsigned int n = INTERLEAVE_TABLE_26_4[i];
bool s = READ_BIT1(data, n);
WRITE_BIT1(vch, i, s);
}
// "Un-whiten" (descramble)
for (unsigned int i = 0U; i < 13U; i++)
vch[i] ^= WHITENING_DATA[i];
for (unsigned int i = 0U; i < 81U; i += 3U) {
unsigned int n = i;
bool bit1 = READ_BIT1(vch, n);
n++;
bool bit2 = READ_BIT1(vch, n);
n++;
bool bit3 = READ_BIT1(vch, n);
if ((bit1 && bit2 && !bit3) || (bit1 && !bit2 && bit3) || (!bit1 && bit2 && bit3)) {
unsigned int n = i;
WRITE_BIT1(vch, n, true);
n++;
WRITE_BIT1(vch, n, true);
n++;
WRITE_BIT1(vch, n, true);
errors++;
} else if ((!bit1 && !bit2 && bit3) || (!bit1 && bit2 && !bit3) || (bit1 && !bit2 && !bit3)) {
unsigned int n = i;
WRITE_BIT1(vch, n, false);
n++;
WRITE_BIT1(vch, n, false);
n++;
WRITE_BIT1(vch, n, false);
errors++;
}
}
// Scramble
for (unsigned int i = 0U; i < 13U; i++)
vch[i] ^= WHITENING_DATA[i];
// Interleave
for (unsigned int i = 0U; i < 104U; i++) {
unsigned int n = INTERLEAVE_TABLE_26_4[i];
bool s = READ_BIT1(vch, i);
WRITE_BIT1(data, n, s);
}
return errors;
}
bool CYSFPayload::processVDMode2Data(unsigned char* data, unsigned char fn, bool gateway)
{
assert(data != NULL);

2
YSFPayload.h
View File

@ -54,8 +54,6 @@ private:
unsigned char* m_source;
unsigned char* m_dest;
CAMBEFEC m_fec;
unsigned int processVDMode2AudioBlock(unsigned char* data);
};
#endif