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119 lines
3 KiB
C++
119 lines
3 KiB
C++
#include "cc_encoder.h"
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#include "cc_common.h"
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#include <volk/volk.h>
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#include <volk/volk_typedefs.h>
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#include <cmath>
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namespace viterbi
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{
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CCEncoder::CCEncoder(int frame_size, int k, int rate, std::vector<int> polys, int start_state)
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: d_rate(rate),
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d_k(k),
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d_polys(polys),
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d_start_state(start_state)
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{
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if (static_cast<size_t>(d_rate) != d_polys.size())
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throw std::runtime_error("cc_encoder: Number of polynomials must be the same as the value of rate");
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if (d_rate < 2)
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throw std::runtime_error("cc_encoder: inverse rate r must be > 2");
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if (k < 2 || k > 31)
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throw std::runtime_error("cc_encoder: constraint length K must in be the range [2, 31]");
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if (d_start_state >= (1u << (d_k - 1)))
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throw std::runtime_error("cc_encoder: start state is invalid; must be in range [0, 2^(K-1)-1] where K is the constraint length");
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if (frame_size < 1)
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throw std::runtime_error("cc_encoder: frame_size must be > 0");
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partab_init();
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d_max_frame_size = frame_size;
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set_frame_size(frame_size);
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}
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CCEncoder::~CCEncoder()
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{
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}
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bool CCEncoder::set_frame_size(unsigned int frame_size)
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{
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bool ret = true;
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if (frame_size > d_max_frame_size)
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{
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frame_size = d_max_frame_size;
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ret = false;
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}
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d_frame_size = frame_size;
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d_output_size = d_rate * d_frame_size;
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return ret;
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}
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double CCEncoder::rate()
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{
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return static_cast<double>(d_rate);
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}
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int CCEncoder::parity(int x)
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{
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x ^= (x >> 16);
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x ^= (x >> 8);
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return parityb(x);
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}
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int CCEncoder::parityb(unsigned char x)
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{
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return Partab[x];
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}
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void CCEncoder::partab_init(void)
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{
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int i, cnt, ti;
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/* Initialize parity lookup table */
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for (i = 0; i < 256; i++)
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{
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cnt = 0;
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ti = i;
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while (ti)
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{
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if (ti & 1)
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cnt++;
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ti >>= 1;
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}
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Partab[i] = cnt & 1;
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}
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}
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void CCEncoder::work(uint8_t *in, uint8_t *out)
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{
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unsigned int my_state = d_start_state;
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for (unsigned int i = 0; i < d_frame_size; ++i)
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{
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my_state = (my_state << 1) | (in[i] & 1);
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for (unsigned int j = 0; j < d_rate; ++j)
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out[i * d_rate + j] = (d_polys[j] < 0) ^ parity(my_state & abs(d_polys[j])) ? 1 : 0;
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}
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d_start_state = my_state;
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}
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void CCEncoder::work(uint8_t *in, uint8_t *out, int size)
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{
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unsigned int my_state = d_start_state;
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for (int i = 0; i < size; ++i)
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{
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my_state = (my_state << 1) | (in[i] & 1);
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for (unsigned int j = 0; j < d_rate; ++j)
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out[i * d_rate + j] = (d_polys[j] < 0) ^ parity(my_state & abs(d_polys[j])) ? 1 : 0;
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}
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d_start_state = my_state;
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}
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}
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