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https://github.com/aicodix/modem.git
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use base40 and one more bit to get three more characters
This commit is contained in:
Ahmet Inan
parent
7e73a251a7
commit
811a3fbb42
4 changed files with 24 additions and 22 deletions
16
decode.cc
16
decode.cc
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@ -80,10 +80,10 @@ struct Decoder : Common
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}
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return 0;
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}
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static void base37_decoder(char *str, int64_t val, int len)
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static void base40_decoder(char *str, int64_t val, int len)
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{
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for (int i = len-1; i >= 0; --i, val /= 37)
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str[i] = " 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"[val%37];
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for (int i = len-1; i >= 0; --i, val /= 40)
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str[i] = " /0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"[val%40];
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}
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const cmplx *mls0_seq()
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{
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@ -207,11 +207,11 @@ struct Decoder : Common
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int64_t meta_data()
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{
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shuffle(code, perm, 8);
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polar_decoder(nullptr, mesg, code, frozen_256_71, 8);
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polar_decoder(nullptr, mesg, code, frozen_256_72, 8);
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int best = -1;
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for (int k = 0; k < mesg_type::SIZE; ++k) {
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crc0.reset();
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for (int i = 0; i < 71; ++i)
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for (int i = 0; i < 72; ++i)
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crc0(mesg[i].v[k] < 0);
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if (crc0() == 0) {
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best = k;
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@ -221,7 +221,7 @@ struct Decoder : Common
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if (best < 0)
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return -1;
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uint64_t md = 0;
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for (int i = 0; i < 55; ++i)
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for (int i = 0; i < 56; ++i)
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md |= uint64_t(mesg[i].v[best] < 0) << i;
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return md;
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}
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@ -375,12 +375,12 @@ struct Decoder : Common
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break;
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}
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int64_t call = meta_info >> 8;
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if (call == 0 || call >= 129961739795077L) {
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if (call == 0 || call >= 262144000000000L) {
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std::cerr << "call sign unsupported." << std::endl;
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break;
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}
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char call_sign[10];
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base37_decoder(call_sign, call, 9);
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base40_decoder(call_sign, call, 9);
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call_sign[9] = 0;
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std::cerr << "call sign: " << call_sign << std::endl;
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int mode = meta_info & 255;
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26
encode.cc
26
encode.cc
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@ -163,13 +163,13 @@ struct Encoder : public Common
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}
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void meta_data(uint64_t md)
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{
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for (int i = 0; i < 55; ++i)
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for (int i = 0; i < 56; ++i)
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mesg[i] = nrz((md >> i) & 1);
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crc0.reset();
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crc0(md << 9);
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crc0(md << 8);
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for (int i = 0; i < 16; ++i)
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mesg[i+55] = nrz((crc0() >> i) & 1);
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polar_encoder(code, mesg, frozen_256_71, 8);
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mesg[i+56] = nrz((crc0() >> i) & 1);
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polar_encoder(code, mesg, frozen_256_72, 8);
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shuffle(meta, code, 8);
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}
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cmplx map_bits(code_type *b, int bits)
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@ -330,17 +330,19 @@ struct Encoder : public Common
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}
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};
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int64_t base37_encoder(const char *str)
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int64_t base40_encoder(const char *str)
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{
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int64_t acc = 0;
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for (char c = *str++; c; c = *str++) {
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acc *= 37;
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if (c >= '0' && c <= '9')
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acc += c - '0' + 1;
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acc *= 40;
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if (c == '/')
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acc += 3;
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else if (c >= '0' && c <= '9')
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acc += c - '0' + 4;
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else if (c >= 'a' && c <= 'z')
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acc += c - 'a' + 11;
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acc += c - 'a' + 14;
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else if (c >= 'A' && c <= 'Z')
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acc += c - 'A' + 11;
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acc += c - 'A' + 14;
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else if (c != ' ')
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return -1;
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}
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@ -366,8 +368,8 @@ int main(int argc, char **argv)
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std::cerr << "Frequency offset must be divisible by 300." << std::endl;
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return 1;
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}
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int64_t call_sign = base37_encoder(argv[6]);
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if (call_sign <= 0 || call_sign >= 129961739795077L) {
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int64_t call_sign = base40_encoder(argv[6]);
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if (call_sign <= 0 || call_sign >= 262144000000000L) {
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std::cerr << "Unsupported call sign." << std::endl;
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return 1;
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}
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@ -28,7 +28,7 @@ void code(int N, int K, double P)
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int main()
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{
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// call sign and mode with 16 bit CRC
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code<8>(256, 47+8+16, 0.5);
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code<8>(256, 48+8+16, 0.5);
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// 1/2-rate payload with 32 bit CRC
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code<11>(2048, 1024+32, 0.33);
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code<12>(4096, 2048+32, 0.34);
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@ -1,4 +1,4 @@
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static const uint32_t frozen_256_71[8] = { 0xffffffff, 0xffffffff, 0x7fffffff, 0x17f7fff, 0x7fffffff, 0x1171fff, 0x17177f, 0x7, };
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static const uint32_t frozen_256_72[8] = { 0xffffffff, 0xffffffff, 0x7fffffff, 0x17f7fff, 0x7fffffff, 0x1171fff, 0x17177f, 0x3, };
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static const uint32_t frozen_2048_1056[64] = { 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0x7fffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0x3fffffff, 0xffffffff, 0x177fffff, 0x177f7fff, 0x1013f, 0xffffffff, 0xffffffff, 0xffffffff, 0x177f7fff, 0x7fffffff, 0x11f7fff, 0x11717ff, 0x10117, 0x1fffffff, 0x117177f, 0x7177f, 0x1, 0x1037f, 0x1, 0x1, 0x0, 0xffffffff, 0x7fffffff, 0x7fffffff, 0x11717ff, 0x17ffffff, 0x17177f, 0x1037f, 0x1, 0x77f7fff, 0x1013f, 0x10117, 0x1, 0x10117, 0x1, 0x0, 0x0, 0x1173fff, 0x10117, 0x10117, 0x0, 0x17, 0x0, 0x0, 0x0, 0x3, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, };
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static const uint32_t frozen_4096_2080[128] = { 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0x7fffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0x177fffff, 0xffffffff, 0xffffffff, 0x7fffffff, 0x37f7fff, 0x7fffffff, 0x1171fff, 0x117177f, 0x117, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0x7fffffff, 0x11f7fff, 0xffffffff, 0x7fffffff, 0x17ffffff, 0x117177f, 0x177f7fff, 0x1077f, 0x1013f, 0x1, 0xffffffff, 0x177fffff, 0x77f7fff, 0x1013f, 0x11f7fff, 0x10117, 0x10117, 0x1, 0x11717ff, 0x10117, 0x17, 0x0, 0x3, 0x0, 0x0, 0x0, 0xffffffff, 0xffffffff, 0xffffffff, 0x7fffffff, 0xffffffff, 0x17ffffff, 0x177f7fff, 0x1077f, 0xffffffff, 0x177f7fff, 0x11f7fff, 0x10117, 0x11717ff, 0x10117, 0x117, 0x0, 0x7fffffff, 0x1171fff, 0x117177f, 0x17, 0x7177f, 0x1, 0x1, 0x0, 0x1017f, 0x1, 0x1, 0x0, 0x1, 0x0, 0x0, 0x0, 0x177fffff, 0x17177f, 0x1037f, 0x1, 0x1011f, 0x1, 0x1, 0x0, 0x10117, 0x1, 0x1, 0x0, 0x1, 0x0, 0x0, 0x0, 0x10117, 0x1, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, };
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static const uint32_t frozen_8192_4128[256] = { 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0x17ffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0x177f7fff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0x7fffffff, 0x7fffffff, 0x11717ff, 0xffffffff, 0x1fffffff, 0x177fffff, 0x17177f, 0x177f7fff, 0x1013f, 0x10117, 0x1, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0x7fffffff, 0xffffffff, 0x7fffffff, 0x17ffffff, 0x117177f, 0xffffffff, 0xffffffff, 0xffffffff, 0x1fffffff, 0xffffffff, 0x177f7fff, 0x77f7fff, 0x1011f, 0x7fffffff, 0x13f7fff, 0x11717ff, 0x10117, 0x117177f, 0x117, 0x7, 0x0, 0xffffffff, 0xffffffff, 0x7fffffff, 0x37f7fff, 0x7fffffff, 0x1171fff, 0x117177f, 0x10117, 0x17ffffff, 0x117177f, 0x3177f, 0x1, 0x1013f, 0x1, 0x1, 0x0, 0x177f7fff, 0x1017f, 0x1011f, 0x1, 0x10117, 0x1, 0x1, 0x0, 0x10117, 0x1, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0x17ffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0x177f7fff, 0x7fffffff, 0x11f7fff, 0x11717ff, 0x10117, 0xffffffff, 0x7fffffff, 0x7fffffff, 0x1171fff, 0x17ffffff, 0x117177f, 0x7177f, 0x1, 0x177f7fff, 0x1077f, 0x1011f, 0x1, 0x10117, 0x1, 0x1, 0x0, 0xffffffff, 0x17ffffff, 0x177f7fff, 0x7177f, 0x37f7fff, 0x1011f, 0x10117, 0x1, 0x1171fff, 0x10117, 0x10117, 0x1, 0x10117, 0x0, 0x0, 0x0, 0x117177f, 0x10117, 0x17, 0x0, 0x3, 0x0, 0x0, 0x0, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x7fffffff, 0x37f7fff, 0x1173fff, 0x10117, 0x11717ff, 0x10117, 0x117, 0x0, 0x117177f, 0x7, 0x1, 0x0, 0x1, 0x0, 0x0, 0x0, 0x1077f, 0x1, 0x1, 0x0, 0x1, 0x0, 0x0, 0x0, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x1011f, 0x1, 0x1, 0x0, 0x1, 0x0, 0x0, 0x0, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, };
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