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MMDVM
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Merge pull request #252 from F4FXL/FM_Ext 

Use pointer/shift/masking for sample unpacking
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Jonathan Naylor 2020-05-08 16:53:32 +01:00 committed by GitHub
parent 604957b3e2 4c6601d778
commit 7c9385beab
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1 changed files with 8 additions and 12 deletions
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FM.cpp
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@ -643,21 +643,17 @@ uint8_t CFM::writeData(const uint8_t* data, uint8_t length)
for (uint8_t i = 0U; i < length; i += 3U) { for (uint8_t i = 0U; i < length; i += 3U) {
uint16_t sample1 = 0U; uint16_t sample1 = 0U;
uint16_t sample2 = 0U; uint16_t sample2 = 0U;
uint16_t MASK = 0x0001U; uint32_t MASK = 0x00000FFFU;
const uint8_t* base = data + i; uint32_t pack = 0U;
for (uint8_t j = 0U; j < 12U; j++, MASK <<= 1) { uint8_t* packPointer = (uint8_t*)&pack;
uint8_t pos1 = j;
uint8_t pos2 = j + 12U;
bool b1 = READ_BIT_AUDIO(base, pos1) != 0U; packPointer[1U] = data[i];
bool b2 = READ_BIT_AUDIO(base, pos2) != 0U; packPointer[2U] = data[i + 1U];
packPointer[3U] = data[i + 2U];
if (b1) sample2 = uint16_t(pack & MASK);
sample1 |= MASK; sample1 = uint16_t(pack >> 12);
if (b2)
sample2 |= MASK;
}
// Convert from uint16_t (0 - +4095) to Q15 (-2048 - +2047) // Convert from uint16_t (0 - +4095) to Q15 (-2048 - +2047)
samples[nSamples++] = q15_t(sample1) - 2048; samples[nSamples++] = q15_t(sample1) - 2048;