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Added free-text encoding (as a fallback)

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This commit is contained in:
Karlis Goba 2019-01-08 11:27:51 +02:00
parent 3f84b984fe
commit dd6599bee6
2 changed files with 27 additions and 14 deletions
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38
ft8/pack.cpp
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@ -223,7 +223,7 @@ int pack77_1(const char *msg, uint8_t *b77) {
}
void packtext77(const char *text, uint8_t *b71) {
void packtext77(const char *text, uint8_t *b77) {
int length = strlen(text);
// Skip leading and trailing spaces
@ -235,20 +235,23 @@ void packtext77(const char *text, uint8_t *b71) {
--length;
}
// Clear the first 72 bits representing a long number
for (int i = 0; i < 9; ++i) {
b71[i] = 0;
b77[i] = 0;
}
// Now express the text as base-42 number stored
// in the first 72 bits of b77
for (int j = 0; j < 13; ++j) {
// Multiply the long integer in b71 by 42
// Multiply the long integer in b77 by 42
uint16_t x = 0;
for (int i = 8; i >= 0; --i) {
x += b71[i] * (uint16_t)42;
b71[i] = (x & 0xFF);
x += b77[i] * (uint16_t)42;
b77[i] = (x & 0xFF);
x >>= 8;
}
// Add index of the current char
// Get the index of the current char
if (j < length) {
int q = char_index(A0, text[j]);
x = (q > 0) ? q : 0;
@ -256,21 +259,30 @@ void packtext77(const char *text, uint8_t *b71) {
else {
x = 0;
}
// Here we double each added number in order to have the result multiplied
// by two as well, so that it's a 71 bit number left-aligned in 72 bits (9 bytes)
x <<= 1;
// Now add the number to our long number
for (int i = 8; i >= 0; --i) {
if (x == 0) break;
x += b71[i];
b71[i] = (x & 0xFF);
x += b77[i];
b77[i] = (x & 0xFF);
x >>= 8;
}
}
// Set n3=0 (bits 71..73) and i3=0 (bits 74..76)
b77[8] &= 0xFE;
b77[9] &= 0x00;
}
int pack77(const char *msg, uint8_t *c77) {
// Check Type 1 (Standard 77-bit message) or Type 2, with optional "/P"
//if (starts_with(msg, "CQ ")) {
return pack77_1(msg, c77);
//}
if (0 == pack77_1(msg, c77)) {
return 0;
}
// TODO:
// Check 0.5 (telemetry)
@ -281,8 +293,8 @@ int pack77(const char *msg, uint8_t *c77) {
// Default to free text
// i3=0 n3=0
// packtext77(msg(1:13),c77(1:71))
// write(c77(72:77),'(2b3.3)') n3,i3
packtext77(msg, c77);
return 0;
}
}; // namespace

3
ft8/unpack.cpp
View file

@ -285,7 +285,8 @@ int unpack_telemetry(const uint8_t *a71, char *telemetry) {
int unpack77(const uint8_t *a77, char *message) {
uint8_t n3, i3;
n3 = (a77[9] >> 6) & 0x07;
// Extract n3 (bits 71..73) and i3 (bits 74..76)
n3 = ((a77[8] << 2) & 0x04) | ((a77[9] >> 6) & 0x03);
i3 = (a77[9] >> 3) & 0x07;
if (i3 == 0 && n3 == 0) {