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Diffstat (limited to 'host/lib/convert/convert_unpack_sc12.cpp')
| -rw-r--r-- | host/lib/convert/convert_unpack_sc12.cpp | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/host/lib/convert/convert_unpack_sc12.cpp b/host/lib/convert/convert_unpack_sc12.cpp new file mode 100644 index 000000000..e98ab73f1 --- /dev/null +++ b/host/lib/convert/convert_unpack_sc12.cpp @@ -0,0 +1,205 @@ +// +// Copyright 2013 Ettus Research LLC +// +// This program is free software: you can redistribute it and/or modify +// it under the terms of the GNU General Public License as published by +// the Free Software Foundation, either version 3 of the License, or +// (at your option) any later version. +// +// This program is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU General Public License for more details. +// +// You should have received a copy of the GNU General Public License +// along with this program. If not, see <http://www.gnu.org/licenses/>. +// + +#include "convert_common.hpp" +#include <uhd/utils/byteswap.hpp> +#include <uhd/utils/msg.hpp> +#include <boost/math/special_functions/round.hpp> +#include <vector> + +using namespace uhd::convert; + +typedef boost::uint32_t (*tohost32_type)(boost::uint32_t); + +struct item32_sc12_3x +{ + item32_t line0; + item32_t line1; + item32_t line2; +}; + +/* + * convert_sc12_item32_3_to_star_4 takes in 3 lines with 32 bit each + * and converts them 4 samples of type 'std::complex<type>'. + * The structure of the 3 lines is as follows: + * _ _ _ _ _ _ _ _ + * |_ _ _1_ _ _|_ _| + * |_2_ _ _|_ _ _3_| + * |_ _|_ _ _4_ _ _| + * + * The numbers mark the position of one complex sample. + */ +template <typename type, tohost32_type tohost> +void convert_sc12_item32_3_to_star_4 +( + const item32_sc12_3x &input, + std::complex<type> &out0, + std::complex<type> &out1, + std::complex<type> &out2, + std::complex<type> &out3, + const double scalar +) +{ + //step 0: extract the lines from the input buffer + const item32_t line0 = tohost(input.line0); + const item32_t line1 = tohost(input.line1); + const item32_t line2 = tohost(input.line2); + const boost::uint64_t line01 = (boost::uint64_t(line0) << 32) | line1; + const boost::uint64_t line12 = (boost::uint64_t(line1) << 32) | line2; + + //step 1: shift out and mask off the individual numbers + const type i0 = type(boost::int16_t(line0 >> 16)*scalar); + const type q0 = type(boost::int16_t(line0 >> 4)*scalar); + + const type i1 = type(boost::int16_t(line01 >> 24)*scalar); + const type q1 = type(boost::int16_t(line1 >> 12)*scalar); + + const type i2 = type(boost::int16_t(line1 >> 0)*scalar); + const type q2 = type(boost::int16_t(line12 >> 20)*scalar); + + const type i3 = type(boost::int16_t(line2 >> 8)*scalar); + const type q3 = type(boost::int16_t(line2 << 4)*scalar); + + //step 2: load the outputs + out0 = std::complex<type>(i0, q0); + out1 = std::complex<type>(i1, q1); + out2 = std::complex<type>(i2, q2); + out3 = std::complex<type>(i3, q3); +} + +template <typename type, tohost32_type tohost> +struct convert_sc12_item32_1_to_star_1 : public converter +{ + convert_sc12_item32_1_to_star_1(void) + { + //NOP + } + + void set_scalar(const double scalar) + { + const int unpack_growth = 16; + _scalar = scalar/unpack_growth; + } + + /* + * This converter takes in 24 bits complex samples, 12 bits I and 12 bits Q, and converts them to type 'std::complex<type>'. + * 'type' is usually 'float'. + * For the converter to work correctly the used managed_buffer which holds all samples of one packet has to be 32 bits aligned. + * We assume 32 bits to be one line. This said the converter must be aware where it is supposed to start within 3 lines. + * + */ + void operator()(const input_type &inputs, const output_type &outputs, const size_t nsamps) + { + /* + * Looking at the line structure above we can identify 4 cases. + * Each corresponds to the start of a different sample within a 3 line block. + * head_samps derives the number of samples left within one block. + * Then the number of bytes the converter has to rewind are calculated. + */ + const size_t head_samps = size_t(inputs[0]) & 0x3; + size_t rewind = 0; + switch(head_samps) + { + case 0: break; + case 1: rewind = 9; break; + case 2: rewind = 6; break; + case 3: rewind = 3; break; + } + + /* + * The pointer *input now points to the head of a 3 line block. + */ + const item32_sc12_3x *input = reinterpret_cast<const item32_sc12_3x *>(size_t(inputs[0]) - rewind); + std::complex<type> *output = reinterpret_cast<std::complex<type> *>(outputs[0]); + + //helper variables + std::complex<type> dummy0, dummy1, dummy2; + size_t i = 0, o = 0; + + /* + * handle the head case + * head_samps holds the number of samples left in a block. + * The 3 line converter is called for the whole block and already processed samples are dumped. + * We don't run into the risk of a SIGSEGV because input will always point to valid memory within a managed_buffer. + * Furthermore the bytes in a buffer remain unchanged after they have been copied into it. + */ + switch (head_samps) + { + case 0: break; //no head + case 1: convert_sc12_item32_3_to_star_4<type, tohost>(input[i++], dummy0, dummy1, dummy2, output[0], _scalar); break; + case 2: convert_sc12_item32_3_to_star_4<type, tohost>(input[i++], dummy0, dummy1, output[0], output[1], _scalar); break; + case 3: convert_sc12_item32_3_to_star_4<type, tohost>(input[i++], dummy0, output[0], output[1], output[2], _scalar); break; + } + o += head_samps; + + //convert the body + while (o+3 < nsamps) + { + convert_sc12_item32_3_to_star_4<type, tohost>(input[i], output[o+0], output[o+1], output[o+2], output[o+3], _scalar); + i++; o += 4; + } + + /* + * handle the tail case + * The converter can be called with any number of samples to be converted. + * This can end up in only a part of a block to be converted in one call. + * We never have to worry about SIGSEGVs here as long as we end in the middle of a managed_buffer. + * If we are at the end of managed_buffer there are 2 precautions to prevent SIGSEGVs. + * Firstly only a read operation is performed. + * Secondly managed_buffers allocate a fixed size memory which is always larger than the actually used size. + * e.g. The current sample maximum is 2000 samples in a packet over USB. + * With sc12 samples a packet consists of 6000kb but managed_buffers allocate 16kb each. + * Thus we don't run into problems here either. + */ + const size_t tail_samps = nsamps - o; + switch (tail_samps) + { + case 0: break; //no tail + case 1: convert_sc12_item32_3_to_star_4<type, tohost>(input[i], output[o+0], dummy0, dummy1, dummy2, _scalar); break; + case 2: convert_sc12_item32_3_to_star_4<type, tohost>(input[i], output[o+0], output[o+1], dummy1, dummy2, _scalar); break; + case 3: convert_sc12_item32_3_to_star_4<type, tohost>(input[i], output[o+0], output[o+1], output[o+2], dummy2, _scalar); break; + } + } + + double _scalar; +}; + +static converter::sptr make_convert_sc12_item32_le_1_to_fc32_1(void) +{ + return converter::sptr(new convert_sc12_item32_1_to_star_1<float, uhd::wtohx>()); +} + +static converter::sptr make_convert_sc12_item32_be_1_to_fc32_1(void) +{ + return converter::sptr(new convert_sc12_item32_1_to_star_1<float, uhd::ntohx>()); +} + +UHD_STATIC_BLOCK(register_convert_unpack_sc12) +{ + uhd::convert::register_bytes_per_item("sc12", 3/*bytes*/); + + uhd::convert::id_type id; + id.num_inputs = 1; + id.num_outputs = 1; + id.output_format = "fc32"; + + id.input_format = "sc12_item32_le"; + uhd::convert::register_converter(id, &make_convert_sc12_item32_le_1_to_fc32_1, PRIORITY_GENERAL); + + id.input_format = "sc12_item32_be"; + uhd::convert::register_converter(id, &make_convert_sc12_item32_be_1_to_fc32_1, PRIORITY_GENERAL); +} |