Added free-text encoding, fixed minor integer width bugs
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500c204f4d
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1 changed files with 78 additions and 40 deletions
96
pack.cpp
96
pack.cpp
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@ -4,8 +4,8 @@
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#include "pack.h"
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#include "pack.h"
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constexpr int NBASE = 37*36*10*27*27*27;
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constexpr int32_t NBASE = 37*36*10*27*27*27L;
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constexpr int NGBASE = 180*180;
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constexpr int32_t NGBASE = 180*180L;
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// Utility functions for characters and strings
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// Utility functions for characters and strings
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@ -54,21 +54,26 @@ void fmtmsg(char *msg_out, const char *msg_in) {
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// Returns integer encoding of a character (number/digit/space).
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// Returns integer encoding of a character (number/digit/space).
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// Alphabet: "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ +-./?"
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// - Digits are encoded as 0..9
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// - Digits are encoded as 0..9
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// - Letters a..z are encoded as 10..35 (case insensitive)
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// - Letters a..z are encoded as 10..35 (case insensitive)
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// - Space is encoded as 36
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// - Space is encoded as 36
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uint8_t nchar(char c) {
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uint8_t nchar(char c) {
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if (is_digit(c)) {
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if (is_digit(c))
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return (c - '0');
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return (c - '0');
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}
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if (is_letter(c))
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if (is_letter(c)) {
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return (to_upper(c) - 'A') + 10;
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return (to_upper(c) - 'A') + 10;
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switch (c) {
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case ' ': return 36;
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case '+': return 37;
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case '-': return 38;
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case '.': return 39;
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case '/': return 40;
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case '?': return 41;
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default: return 36; // Equal to ' '
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}
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}
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if (c == ' ') {
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return 36;
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}
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// we should never reach here
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return 36;
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}
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}
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@ -327,6 +332,37 @@ int16_t packgrid(const char *grid) {
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return ng;
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return ng;
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}
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}
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// Pack a free-text message into 3 integers (28+28+15 bits)
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void packtext(const char *msg, int32_t &nc1, int32_t &nc2, int16_t &ng) {
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int32_t nc3;
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nc1 = nc2 = ng = 0;
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// Pack 5 characters (42^5) into 27 bits
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for (int i = 0; i < 5; ++i) { // First 5 characters in nc1
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uint8_t j = nchar(msg[i]); // Get character code
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nc1 = 42*nc1 + j;
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}
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// Pack 5 characters (42^5) into 27 bits
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for (int i = 5; i < 10; ++i) { // Characters 6-10 in nc2
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uint8_t j = nchar(msg[i]); // Get character code
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nc2 = 42*nc2 + j;
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}
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// Pack 3 characters (42^3) into 17 bits
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for (int i = 10; i < 13; ++i) { // Characters 11-13 in nc3
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uint8_t j = nchar(msg[i]); // Get character code
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nc3 = 42*nc3 + j;
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}
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// We now have used 17 bits in nc3. Must move one each to nc1 and nc2.
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nc1 <<= 1;
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if (nc3 & 0x08000) nc1 |= 1;
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nc2 <<= 1;
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if (nc3 & 0x10000) nc2 |= 1;
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ng = nc3 & 0x7FFF;
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}
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int packmsg(const char *msg, uint8_t *dat) { // , itype, bcontest
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int packmsg(const char *msg, uint8_t *dat) { // , itype, bcontest
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// TODO: check what is maximum allowed length?
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// TODO: check what is maximum allowed length?
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@ -362,20 +398,21 @@ int packmsg(const char *msg, uint8_t *dat) { // , itype, bcontest
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}
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}
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}
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}
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int32_t nc1 = -1;
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int32_t nc2 = -1;
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int16_t ng = -1;
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// Try to split the message into three space-delimited fields
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// Try to split the message into three space-delimited fields
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// by locating spaces and changing them to zero terminators
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// by locating spaces and changing them to zero terminators
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// Locate the first delimiter in the message
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// Locate the first delimiter in the message
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char *s1 = strchr(msg2, ' ');
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char *s1 = (char *)strchr(msg2, ' ');
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if (s1 == NULL) {
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if (s1 != NULL) {
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// TODO: handle this (plain text message?)
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return -2;
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}
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*s1 = 0; // Separate fields by zero terminator
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*s1 = 0; // Separate fields by zero terminator
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++s1; // Now s1 points to the second field
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++s1; // s1 now points to the second field
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// Locate the second delimiter in the message
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// Locate the second delimiter in the message
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char *s2 = strchr(s1 + 1, ' ');
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char *s2 = (char *)strchr(s1 + 1, ' ');
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if (s2 == NULL) {
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if (s2 == NULL) {
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// If the second space is not found, point to the end of string
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// If the second space is not found, point to the end of string
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// to allow for blank grid (third field)
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// to allow for blank grid (third field)
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@ -383,28 +420,29 @@ int packmsg(const char *msg, uint8_t *dat) { // , itype, bcontest
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}
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}
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else {
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else {
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*s2 = 0;// Separate fields by zero terminator
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*s2 = 0;// Separate fields by zero terminator
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++s2; // Now s2 points to the third field
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++s2; // s2 now points to the third field
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}
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}
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// TODO: process callsign prefixes/suffixes
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// TODO: process callsign prefixes/suffixes
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// Pack message fields into integers
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// Pack message fields into integers
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int nc1 = packcall(msg2);
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nc1 = packcall(msg2);
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int nc2 = packcall(s1);
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nc2 = packcall(s1);
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int ng = packgrid(s2);
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ng = packgrid(s2);
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// TODO: plain text messages
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//call packtext(msg,nc1,nc2,ng)
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//ng=ng+32768
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if (nc1 < 0 || nc2 < 0 || ng < 0) {
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return -3;
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}
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}
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// Check for success in all three fields
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if (nc1 < 0 || nc2 < 0 || ng < 0) {
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// Treat as plain text message
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packtext(msg2, nc1, nc2, ng);
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ng += 0x8000; // Set bit 15 (we abuse signed int here)
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}
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//LOG("nc1 = %d [%04X], nc2 = %d [%04X], ng = %d\n", nc1, nc1, nc2, nc2, ng);
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//LOG("nc1 = %d [%04X], nc2 = %d [%04X], ng = %d\n", nc1, nc1, nc2, nc2, ng);
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// Originally the data was packed in bytes of 6 bits.
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// Originally the data was packed in bytes of 6 bits.
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// This seems to waste memory unnecessary and complicate the code, so we pack it in 8 bit values.
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// This seems to waste memory unnecessary and complicate the code, so we pack it in 8 bit values.
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pack3_8bit(nc1, nc2, ng, dat);
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pack3_8bit((uint32_t)nc1, (uint32_t)nc2, (uint16_t)ng, dat);
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//pack3_6bit(nc1, nc2, ng, dat);
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//pack3_6bit(nc1, nc2, ng, dat);
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return 0; // Success!
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return 0; // Success!
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