From 18dc2b1eaba1221becce8b86aaf50e3569206043 Mon Sep 17 00:00:00 2001
From: Karlis Goba <karlis.goba@gmail.com>
Date: Fri, 26 Oct 2018 15:48:27 +0300
Subject: [PATCH] Added draft versions of unpack routines

---
 unpack.cpp | 192 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 unpack.h   |   6 ++
 2 files changed, 198 insertions(+)
 create mode 100644 unpack.cpp
 create mode 100644 unpack.h

diff --git a/unpack.cpp b/unpack.cpp
new file mode 100644
index 0000000..6c41a56
--- /dev/null
+++ b/unpack.cpp
@@ -0,0 +1,192 @@
+#include "unpack.h"
+#include "text.h"
+
+#include <string.h>
+
+constexpr uint32_t NBASE = 37L*36L*10L*27L*27L*27L;
+
+
+// convert packed character to ASCII character
+// 0..9 a..z space +-./?
+char charn(uint8_t c) {
+    if (c >= 0 && c <= 9)
+        return '0' + c;
+    if (c >= 10 && c < 36)
+        return 'A' + c - 10;
+
+    if (c < 42)
+        return " +-./?" [c - 36];
+
+    return ' ';
+}
+
+
+// nc is a 28-bit integer, e.g. nc1 or nc2, containing all the
+// call sign bits from a packed message.
+void unpackcall(uint32_t nc, char *callsign) {
+    callsign[5] = charn((nc % 27) + 10); // + 10 b/c only alpha+space
+    nc /= 27;
+    callsign[4] = charn((nc % 27) + 10);
+    nc /= 27;
+    callsign[3] = charn((nc % 27) + 10);
+    nc /= 27;
+    callsign[2] = charn(nc % 10); // digit only
+    nc /= 10;
+    callsign[1] = charn(nc % 36); // letter or digit
+    nc /= 36;
+    callsign[0] = charn(nc);
+
+    callsign[6] = 0;
+}
+
+
+// extract maidenhead locator
+void unpackgrid(uint32_t ng, char *grid) {
+    // start of special grid locators for sig strength &c.
+    NGBASE = 180*180
+
+    if ng == NGBASE+1:
+        return "    "
+    if ng >= NGBASE+1 and ng < NGBASE+31:
+        return " -%02d" % (ng - (NGBASE+1)) // sig str, -01 to -30 DB
+    if ng >= NGBASE+31 and ng < NGBASE+62:
+        return "R-%02d" % (ng - (NGBASE+31))
+    if ng == NGBASE+62:
+        return "RO  "
+    if ng == NGBASE+63:
+        return "RRR "
+    if ng == NGBASE+64:
+        return "73  "
+
+    lat = (ng % 180) - 90
+    ng = int(ng / 180)
+    lng = (ng * 2) - 180
+
+    g = "%c%c%c%c" % (ord('A') + int((179-lng)/20),
+                        ord('A') + int((lat+90)/10),
+                        ord('0') + int(((179-lng)%20)/2),
+                        ord('0') + (lat+90)%10)
+
+    if g[0:2] == "KA":
+        // really + signal strength
+        sig = int(g[2:4]) - 50
+        return "+%02d" % (sig)
+
+    if g[0:2] == "LA":
+        // really R+ signal strength
+        sig = int(g[2:4]) - 50
+        return "R+%02d" % (sig)    
+}
+
+
+void unpacktext(uint32_t nc1, uint32_t nc2, uint16_t ng, char *text) {
+    uint32_t nc3 = ng & 0x7FFF;
+
+    if (nc1 & 1 != 0)
+        nc3 |= 0x08000;
+    nc1 >>= 1;
+
+    if (nc2 & 1 != 0)
+        nc3 |= 0x10000;
+    nc2 >>= 1;
+
+    for (int i = 4; i >= 0; --i) {
+        text[i] = charn(nc1 % 42);
+        nc1 /= 42;
+    }
+
+    for (int i = 9; i >= 5; --i) {
+        text[i] = charn(nc2 % 42);
+        nc2 /= 42;
+    }
+
+    for (int i = 12; i >= 10; --i) {
+        text[i] = charn(nc3 % 42);
+        nc3 /= 42;
+    }
+
+    text[13] = 0;
+}
+
+
+int unpack(const uint8_t *a72, char *message) {
+    uint32_t nc1, nc2;
+    uint16_t ng;
+
+    nc1 = (a72[0] << 20);
+    nc1 |= (a72[1] << 12);
+    nc1 |= (a72[2] << 4);
+    nc1 |= (a72[3] >> 4);
+    
+    nc2 = (a72[3] << 24);
+    nc2 |= (a72[4] << 16);
+    nc2 |= (a72[5] << 8);
+    nc2 |= (a72[6]);
+
+    ng = (a72[7] >> 8);
+    ng |= (a72[8]);
+
+    if (ng & 0x8000) {
+        unpacktext(nc1, nc2, ng, message);
+        return 0;
+    }
+
+    char c2[7];
+    char grid[5];
+
+    if (nc1 == NBASE+1) {
+        // CQ with standard callsign
+        unpackcall(nc2, c2);
+        unpackgrid(ng, grid);
+        strcpy(message, "CQ ");
+        strcat(message, c2);
+        strcat(message, " ");
+        strcat(message, grid);
+        return 0;
+    }
+
+    if (nc1 >= 267649090L && nc1 <= 267698374L) {
+        // CQ with suffix (e.g. /QRP)
+        uint32_t n = nc1 - 267649090L;
+        char sf[4];
+        sf[0] = charn(n % 37);
+        n /= 37;
+        sf[1] = charn(n % 37);
+        n /= 37;
+        sf[2] = charn(n % 37);
+
+        unpackcall(nc2, c2);
+        unpackgrid(ng, grid);
+
+        strcpy(message, "CQ ");
+        strcat(message, c2);
+        strcat(message, "/");
+        strcat(message, sf);
+        strcat(message, " ");
+        strcat(message, grid);
+        return 0;
+    }
+
+    char c1[7];
+    
+    unpackcall(nc1, c1);
+    if (equals(c1, "CQ9DX ")) {
+        strcpy(c1, "CQ DX");
+    }
+    else if (starts_with(c1, " E9") && is_letter(c1[3]) && is_letter(c1[4]) && is_space(c1[5])) {
+        strcpy(c1, "CQ ");
+        c1[5] = 0;
+    }
+    unpackcall(nc2, c2);
+    unpackgrid(ng, grid);
+
+    strcpy(message, c1);
+    strcat(message, " ");
+    strcat(message, c2);
+    strcat(message, " ");
+    strcat(message, grid);
+
+    //if "000AAA" in msg:
+    //    return None
+    return 0;
+}
diff --git a/unpack.h b/unpack.h
new file mode 100644
index 0000000..eaa1a99
--- /dev/null
+++ b/unpack.h
@@ -0,0 +1,6 @@
+#pragma once
+
+#include <stdint.h>
+
+
+int unpack(const uint8_t *a72, char *message);