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Fix register unpacking for Labsat3W files

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This change fixes a bug in the unpacking of Labsat 3 Wideband files
when using the Labsat_Signal_Source. The original endian conversion
loop includes a cast from char->uint64_t that (surprisingly) incurs a sign
extension when the MSB of the char is set. ORing the unmasked uint64_t
into the register can set undesired bits.

The changes replace the old endian conversion loop with a ``boost`` utility
function.

Signed-off-by: Jeff Melville <dev@jeffmelville.com>
This commit is contained in:
Jeff Melville 2022-09-20 10:16:02 -04:00
parent 97cf4135e0
commit b6c7e4a6f1
1 changed files with 6 additions and 8 deletions
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14
src/algorithms/signal_source/gnuradio_blocks/labsat23_source.cc
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@ -21,6 +21,7 @@
#include "INIReader.h"
#include "command_event.h"
#include "gnss_sdr_make_unique.h"
#include <boost/endian/conversion.hpp>
#include <gnuradio/io_signature.h>
#include <algorithm>
#include <array>
@ -737,7 +738,8 @@ void labsat23_source::decode_ls3w_register(uint64_t input, std::vector<gr_comple
{
std::bitset<64> bs(input);
// Reverse, since register are written to file as 64-bit little endian words
// Earlier samples are written in the MSBs of the register. Bit-reverse the register
// for easier indexing. Note this bit-reverses individual samples as well for quant > 1 bit
for (std::size_t i = 0; i < 32; ++i)
{
bool t = bs[i];
@ -1074,14 +1076,10 @@ int labsat23_source::general_work(int noutput_items,
std::size_t output_pointer = 0;
for (int i = 0; i < registers_to_read; i++)
{
std::array<char, 8> memory_block{};
binary_input_file.read(memory_block.data(), 8);
uint64_t read_register = 0ULL;
for (int k = 7; k >= 0; --k)
{
read_register <<= 8;
read_register |= uint64_t(memory_block[k]);
}
// Labsat3W writes its 64-bit shift register to files in little endian. Read and convert to host endianness.
binary_input_file.read(reinterpret_cast<char *>(&read_register), sizeof(read_register));
boost::endian::little_to_native_inplace(read_register);
if (binary_input_file.gcount() == 8)
{