add numeric message encoding

README.md

@@ -1,4 +1,4 @@
-Go port of the POCSAG::Encode Perl module.
+Golang port of the `POCSAG::Encode` Perl module extended to support Numeric as well as AlphaNumeric messages.
 
 Example usage
 
@@ -6,7 +6,6 @@ Example usage
 package main
 
 import (
-	"fmt"
 	"log"
 
 	"github.com/kgolding/go-pocsagencode"
@@ -14,12 +13,7 @@ import (
 
 func main() {
 	messages := []*pocsagencode.Message{
-		&pocsagencode.Message{1300100, "Hello Pager!"},
-	}
-
-	for i := 0; i < 50; i++ {
-		addr := uint32(1200000 + i*100)
-		messages = append(messages, &pocsagencode.Message{addr, fmt.Sprintf("Hello pager number %d", addr)})
+		&pocsagencode.Message{1300100, "Hello Pager!", false},
 	}
 
 	log.Println("Sending", len(messages), "messages")

examples/cli/main.go

@@ -1,29 +1,49 @@
 package main
 
 import (
+	"flag"
 	"fmt"
+	"log"
 	"os"
+	"path/filepath"
 	"strconv"
 
 	pc "github.com/kgolding/go-pocsagencode"
 )
 
 func main() {
-	if len(os.Args) != 3 {
-		fmt.Printf("Usage: %s <pager addr> <text message>\ne.g. %s 13100100 'Hello world!'\n", os.Args[0], os.Args[0])
+	var num bool
+	var debug bool
+
+	flag.BoolVar(&num, "num", false, "send as numeric message")
+	flag.BoolVar(&debug, "v", false, "verbose logging")
+	flag.Parse()
+
+	if len(flag.Args()) != 2 {
+		me := filepath.Base(os.Args[0])
+		fmt.Printf(`
+Usage: %s [-num] <pager addr> <text or numeric message>
+  Examples:  %s 13100100 'Hello world!'
+             %s -num 13100100 9876\n`, me, me, me)
 		os.Exit(1)
 	}
-	addr, err := strconv.Atoi(os.Args[1])
+	addr, err := strconv.Atoi(flag.Arg(0))
 	if err != nil {
 		fmt.Println("Invalid pager addr - must be a number")
 		os.Exit(2)
 	}
 	messages := []*pc.Message{
 		&pc.Message{
-			Addr:    uint32(addr),
-			Content: os.Args[2],
+			Addr:      uint32(addr),
+			Content:   flag.Arg(0),
+			IsNumeric: num,
 		},
 	}
+
+	if debug {
+		pc.SetLogger(log.New(os.Stdout, "", log.Lshortfile))
+	}
+
 	burst, _ := pc.Generate(messages)
 
 	fmt.Printf("Message: %s\n\n", burst.String())

examples/sendmultiple/main.go

@@ -9,12 +9,12 @@ import (
 
 func main() {
 	messages := []*pocsagencode.Message{
-		&pocsagencode.Message{1300100, "Hello Pager!"},
+		&pocsagencode.Message{1300100, "Hello Pager!", false},
 	}
 
 	for i := 0; i < 50; i++ {
 		addr := uint32(1200000 + i*100)
-		messages = append(messages, &pocsagencode.Message{addr, fmt.Sprintf("Hello pager number %d", addr)})
+		messages = append(messages, &pocsagencode.Message{addr, fmt.Sprintf("Hello pager number %d", addr), false})
 	}
 
 	log.Println("Sending", len(messages), "messages")

pocsagencode.go

@@ -6,8 +6,9 @@ import (
 
 // Message is a single POCSAG Alphanumeric message
 type Message struct {
-	Addr    uint32
-	Content string
+	Addr      uint32
+	Content   string
+	IsNumeric bool
 }
 
 var logger *log.Logger
@@ -185,6 +186,81 @@ func appendContentText(content string) (int, Burst) {
 	return pos, out
 }
 
+// appendContentNumeric appends numeric message content to the transmission blob
+func appendContentNumeric(content string) (int, Burst) {
+	out := make(Burst, 0)
+	debugf("appendContentNumeric: %s", content)
+
+	// 084 2.6]195-3U7[
+	charMap := map[byte]byte{
+		'0': 0, '8': 1, '4': 2, ' ': 3, '2': 4, '.': 5, '6': 6, ']': 7,
+		'1': 8, '9': 9, '5': 10, '-': 11, '3': 12, 'U': 13, '7': 14, '[': 15,
+	}
+
+	bitpos := 0
+	word := uint32(0)
+	leftbits := 0
+	pos := 0
+
+	// walk through characters in message
+	for i, r := range content {
+		var char byte
+		var ok bool
+		// set char from the charMap, and skip the character is not in the map
+		if char, ok = charMap[byte(r)]; !ok {
+			debugf("skipping invlaid char '%s'", string(r))
+			continue
+		}
+
+		debugf("  char %d: %d [%X]\n", i, char, char)
+
+		//  if the bits won't fit:
+		if bitpos+4 > 20 {
+			space := 20 - bitpos
+			//  leftbits least significant bits of $char are left over in the next word
+			leftbits = 4 - space
+			debugf("  bits of char won't fit since bitpos is %d, got %d bits free, leaving %d bits in next word", bitpos, space, leftbits)
+		}
+
+		word |= (uint32(char) << uint(31-4-bitpos))
+
+		bitpos += 4
+
+		if bitpos >= 20 {
+			debugf("   appending word: %X\n", word)
+			out = append(out, appendMessageCodeword(word))
+			pos++
+			word = 0
+			bitpos = 0
+		}
+
+		if leftbits > 0 {
+			word |= (uint32(char) << uint(31-leftbits))
+			bitpos = leftbits
+			leftbits = 0
+		}
+	}
+
+	if bitpos > 0 {
+		debugf("  got %d bits in word at end of text, word: %X", bitpos, word)
+		step := 0
+		for bitpos < 20 {
+			if step == 2 {
+				word |= (1 << uint(30-bitpos))
+			}
+			bitpos++
+			step++
+			if step == 4 {
+				step = 0
+			}
+		}
+		out = append(out, appendMessageCodeword(word))
+		pos++
+	}
+
+	return pos, out
+}
+
 // appendMessage appends a single message to the end of the transmission blob.
 func appendMessage(startpos int, msg *Message) (int, Burst) {
 	// expand the parameters of the message
@@ -217,7 +293,13 @@ func appendMessage(startpos int, msg *Message) (int, Burst) {
 	pos++
 
 	// Next, append the message contents
-	contentEncLen, contentEnc := appendContentText(content)
+	var contentEncLen int
+	var contentEnc Burst
+	if msg.IsNumeric {
+		contentEncLen, contentEnc = appendContentNumeric(content)
+	} else {
+		contentEncLen, contentEnc = appendContentText(content)
+	}
 
 	tx = append(tx, contentEnc...)
 	pos += contentEncLen
@@ -296,7 +378,7 @@ func selectMsg(pos int, msgListRef []*Message) int {
 // in the next Generate() call and sent in the next brrraaaap.
 func Generate(messages []*Message, optionFns ...OptionFn) (Burst, []*Message) {
 	options := &Options{
-		MaxLen:       3000,
+		MaxLen:       2000,
 		PreambleBits: 576,
 	}
 	for _, opt := range optionFns {

pocsagencode_test.go

@@ -1,13 +1,51 @@
 package pocsagencode
 
 import (
+	"log"
+	"os"
 	"testing"
 )
 
-func Test_Encode(t *testing.T) {
+func init() {
+	SetLogger(log.New(os.Stdout, "POCSAG ", log.LstdFlags))
+	// Comment below to enable debug logging
+	SetLogger(nil)
+}
+
+func Test_Encode_Numeric(t *testing.T) {
+
+	enc, left := Generate([]*Message{
+		&Message{1300100, "12[3]", true},
+	})
+	if len(left) != 0 {
+		t.Errorf("expect no message left, got %v", left)
+	}
+
+	expect := Burst{
+		// 18 words, 576 bits of preamble
+		0xAAAAAAAA, 0xAAAAAAAA,
+		0xAAAAAAAA, 0xAAAAAAAA, 0xAAAAAAAA, 0xAAAAAAAA, 0xAAAAAAAA, 0xAAAAAAAA, 0xAAAAAAAA, 0xAAAAAAAA,
+		0xAAAAAAAA, 0xAAAAAAAA, 0xAAAAAAAA, 0xAAAAAAAA, 0xAAAAAAAA, 0xAAAAAAAA, 0xAAAAAAAA, 0xAAAAAAAA,
+		// The real data starts here
+		0x7CD215D8, 0x7A89C197, 0x7A89C197, 0x7A89C197, 0x7A89C197, 0x7A89C197, 0x7A89C197, 0x7A89C197,
+		0x7A89C197, 0x4F5A0109, 0xC27E3D14, 0x7A89C197, 0x7A89C197,
+	}
+
+	if len(enc) != len(expect) {
+		t.Errorf("expected:\n%s\ngot:\n%s\n", expect, enc)
+	} else {
+		for i, w := range expect {
+			if w != enc[i] {
+				t.Errorf("expected:%X got:%X at index %d\n", w, enc[i], i)
+			}
+		}
+	}
+}
+
+func Test_Encode_Alpha(t *testing.T) {
 	// SetLogger(log.New(os.Stdout, "POCSAG ", log.LstdFlags))
 	enc, left := Generate([]*Message{
-		&Message{1300100, "happy christmas!"},
+		&Message{1300100, "happy christmas!", false},
 	})
 	if len(left) != 0 {
 		t.Errorf("expect no message left, got %v", left)