From 722b591839ec84db1de0aeac48adf686892f5cb3 Mon Sep 17 00:00:00 2001
From: Patrick Moessler <pub@asaril.de>
Date: Sun, 20 Oct 2019 23:49:17 +0200
Subject: [PATCH] Switch to COBS

---
 app/src/main/java/CobsUtils.kt                | 92 +++++++++++++++++++
 .../java/de/asaril/bletail/MainActivity.kt    | 21 +----
 app/src/main/res/values/strings.xml           |  2 +-
 3 files changed, 94 insertions(+), 21 deletions(-)
 create mode 100644 app/src/main/java/CobsUtils.kt

diff --git a/app/src/main/java/CobsUtils.kt b/app/src/main/java/CobsUtils.kt
new file mode 100644
index 0000000..e9be5b9
--- /dev/null
+++ b/app/src/main/java/CobsUtils.kt
@@ -0,0 +1,92 @@
+import kotlin.experimental.and
+
+//This file was converted to Kotlin. Original Java file license below:
+
+//The MIT License (MIT)
+//
+//Copyright (c) 2016 Suresh Joshi
+//
+//Permission is hereby granted, free of charge, to any person obtaining a copy
+//of this software and associated documentation files (the "Software"), to deal
+//in the Software without restriction, including without limitation the rights
+//to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//copies of the Software, and to permit persons to whom the Software is
+//furnished to do so, subject to the following conditions:
+//
+//The above copyright notice and this permission notice shall be included in all
+//copies or substantial portions of the Software.
+//
+//THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//SOFTWARE.
+
+class CobsUtils {
+
+    companion object {
+        // Expected to be the entire packet to encode
+        fun encode(packet: ByteArray?): ByteArray {
+            if (packet == null || packet.isEmpty()) {
+                return byteArrayOf()
+            }
+
+            val output = ByteArray(packet.size + 2)
+            var blockStartValue: Byte = 1
+            var lastZeroIndex = 0
+            var srcIndex = 0
+            var destIndex = 1
+
+            while (srcIndex < packet.size) {
+                if (packet[srcIndex].toInt() == 0) {
+                    output[lastZeroIndex] = blockStartValue
+                    lastZeroIndex = destIndex++
+                    blockStartValue = 1
+                } else {
+                    output[destIndex++] = packet[srcIndex]
+                    if ((++blockStartValue).toInt() == 255) {
+                        output[lastZeroIndex] = blockStartValue
+                        lastZeroIndex = destIndex++
+                        blockStartValue = 1
+                    }
+                }
+
+                ++srcIndex
+            }
+
+            output[lastZeroIndex] = blockStartValue
+            return output
+        }
+
+        // Expected to be the entire packet to decode with trailing 0
+        fun decode(packet: ByteArray?): ByteArray {
+            if (packet == null
+                || packet.isEmpty()
+                || packet[packet.size - 1].toInt() != 0
+            ) {
+                return byteArrayOf()
+            }
+
+            val output = ByteArray(packet.size - 2)
+            val srcPacketLength = packet.size - 1
+            var srcIndex = 0
+            var destIndex = 0
+
+            while (srcIndex < srcPacketLength) {
+                val code = packet[srcIndex++] and 0xff.toByte()
+                var i = 1
+                while (srcIndex < srcPacketLength && i < code) {
+                    output[destIndex++] = packet[srcIndex++]
+                    ++i
+                }
+                if (code != 0xff.toByte() && srcIndex != srcPacketLength) {
+                    output[destIndex++] = 0
+                }
+            }
+
+            return output
+        }
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/java/de/asaril/bletail/MainActivity.kt b/app/src/main/java/de/asaril/bletail/MainActivity.kt
index b239a80..b129b35 100644
--- a/app/src/main/java/de/asaril/bletail/MainActivity.kt
+++ b/app/src/main/java/de/asaril/bletail/MainActivity.kt
@@ -181,25 +181,6 @@ class MainActivity : AppCompatActivity() {
         }
     }
 
-    private fun encodeSlip(payload: ByteArray): ByteArray {
-        var output = ByteArray(0)
-        for (b in payload) {
-            when (b) {
-                END -> {
-                    output += ESC
-                    output += ESC_END
-                }
-                ESC -> {
-                    output += ESC
-                    output += ESC_ESC
-                }
-                else -> output += b
-            }
-        }
-        output += END
-        return output
-    }
-
     fun powerOffClick(item: MenuItem) {
         val r: fx.Fx.Root.Builder = fx.Fx.Root.newBuilder()
         r.halt = fx.Fx.halt_msg.newBuilder().build()
@@ -220,7 +201,7 @@ class MainActivity : AppCompatActivity() {
     }
 
     fun sendToBleUart(msgRaw: ByteArray) {
-        val arr: ByteArray = encodeSlip(msgRaw)
+        val arr: ByteArray = CobsUtils.encode(msgRaw)
         fun ByteArray.toHexString() = joinToString("") { "%02x".format(it) }
         Log.i("BLEtail", "tx:" + arr.toHexString())
         this.rxChar!!.value = arr
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 25e62e4..0e7f791 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -7,7 +7,7 @@
     <string name="seg2">2</string>
     <string name="seg1">1</string>
     <string name="number_of_segments">Number of segments</string>
-    <string name="segment">Segment %1$d</string>
+    <string name="segment">Segment $1%d</string>
     <string name="segment_color_2">Segment Color 2</string>
     <string name="segment_color_1">Segment Color 1</string>
     <string name="segment_color_0">Segment Color 0</string>