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use base40 and one more bit to get three more characters

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This commit is contained in:
Ahmet Inan 2025-11-25 03:19:57 +01:00
commit 811a3fbb42
4 changed files with 24 additions and 22 deletions
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16
decode.cc
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@ -80,10 +80,10 @@ struct Decoder : Common
}
return 0;
}
static void base37_decoder(char *str, int64_t val, int len)
static void base40_decoder(char *str, int64_t val, int len)
{
for (int i = len-1; i >= 0; --i, val /= 37)
str[i] = " 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"[val%37];
for (int i = len-1; i >= 0; --i, val /= 40)
str[i] = " /0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"[val%40];
}
const cmplx *mls0_seq()
{
@ -207,11 +207,11 @@ struct Decoder : Common
int64_t meta_data()
{
shuffle(code, perm, 8);
polar_decoder(nullptr, mesg, code, frozen_256_71, 8);
polar_decoder(nullptr, mesg, code, frozen_256_72, 8);
int best = -1;
for (int k = 0; k < mesg_type::SIZE; ++k) {
crc0.reset();
for (int i = 0; i < 71; ++i)
for (int i = 0; i < 72; ++i)
crc0(mesg[i].v[k] < 0);
if (crc0() == 0) {
best = k;
@ -221,7 +221,7 @@ struct Decoder : Common
if (best < 0)
return -1;
uint64_t md = 0;
for (int i = 0; i < 55; ++i)
for (int i = 0; i < 56; ++i)
md |= uint64_t(mesg[i].v[best] < 0) << i;
return md;
}
@ -375,12 +375,12 @@ struct Decoder : Common
break;
}
int64_t call = meta_info >> 8;
if (call == 0 || call >= 129961739795077L) {
if (call == 0 || call >= 262144000000000L) {
std::cerr << "call sign unsupported." << std::endl;
break;
}
char call_sign[10];
base37_decoder(call_sign, call, 9);
base40_decoder(call_sign, call, 9);
call_sign[9] = 0;
std::cerr << "call sign: " << call_sign << std::endl;
int mode = meta_info & 255;