Remove hex manipulation code and use Nordic Intel Hex lib

editor.html

@@ -253,6 +253,7 @@ <h2><i class="fa fa-unlock-alt"></i> <strong>{{ title }}</strong></h2>
         <script src="static/js/encoding.js" type="application/javascript"></script>
         <script src="static/js/mustache.min.js"
             type="application/javascript"></script>
+        <script src="static/js/intel-hex.browser.js" type="application/javascript"></script>
         <script src="blockly/blockly_compressed.js"></script>
         <script src="blockly/blocks_compressed.js"></script>
         <script src="blockly/python_compressed.js"></script>
@@ -270,11 +271,13 @@ <h2><i class="fa fa-unlock-alt"></i> <strong>{{ title }}</strong></h2>
         <script src="microbit_blocks/generators/speech.js"></script>
         <script src="microbit_blocks/generators/python.js"></script>
         <script src="blockly/msg/js/en.js"></script>
-	    <script src="microbit_blocks/messages/en/messages.js"></script>
+        <script src="microbit_blocks/messages/en/messages.js"></script>
         <script src="static/js/ResizeSensor.js"></script>
         <script src="static/js/ElementQueries.js"></script>
 	    <script src="lzma/lzma_worker.js"></script>
 	    <script src="base64-js/base64.js"></script>
+        <script src="hexlify.js"
+            type="application/javascript"></script>
         <script src="python-main.js"
             type="application/javascript"></script>
         <script>vex.defaultOptions.className = 'vex-theme-wireframe';</script>

hexlify.js

@@ -0,0 +1,129 @@
+/**
+ * Module to add and remove Python scripts into and from a MicroPython hex.
+ */
+var upyhex = (function() {
+    'use strict';
+
+    /** User script located at specific flash address. */
+    var USER_CODE_START_ADDR = 0x3e000;
+    var USER_CODE_LEN = 8 * 1024;
+    var USER_CODE_END_ADDR = USER_CODE_START_ADDR + USER_CODE_LEN;
+
+    /** User code header */
+    var USER_CODE_HEADER_SIZE = 4;
+    var USER_CODE_HEADER_START_B0_INDEX = 0;
+    var USER_CODE_HEADER_START_B1_INDEX = 1;
+    var USER_CODE_HEADER_LEN_LSB_INDEX = 2;
+    var USER_CODE_HEADER_LEN_MSB_INDEX = 3;
+
+    /** Number of data bytes per Intel Hex record (line). */
+    var INTEL_HEX_BYTE_CNT = 16;
+
+    /** Start of user script marked by "MP" + 2 bytes for the script length. */
+    var USER_CODE_HEADER_START_B0 = 77;    // 'M'
+    var USER_CODE_HEADER_START_B1 = 80;    // 'P'
+
+    /**
+     * String placed inside the MicroPython hex string to indicate where to
+     * paste the Python Code
+     * */
+    var HEX_INSERTION_POINT = ":::::::::::::::::::::::::::::::::::::::::::\n";
+
+    /**
+     * Converts a string into a byte array of characters.
+     * TODO: Update to encode to UTF-8 correctly.
+     * @param {Uint8Array|Object[]} byteArray - Array of bytes to convert.
+     * @return {string} String output from the conversion.
+     */
+    function strToBytes(str) {
+        var data = new Uint8Array(str.length);
+        for (var i = 0; i < str.length; i++) {
+            // TODO: This will only keep the LSB from the UTF-16 code points
+            data[i] = str.charCodeAt(i);
+        }
+        return data;
+    }
+
+    /**
+     * Converts a byte array into a string of characters.
+     * TODO: This currently only deals with single byte characters, so needs to
+     *       be expanded to support UTF-8 characters longer than 1 byte.
+     * @param {Uint8Array|Object[]} byteArray - Array of bytes to convert.
+     * @return {string} String output from the conversion.
+     */
+    function bytesToStr(byteArray) {
+        var result = [];
+        for (var i = 0; i < byteArray.length; i++) {
+            result.push(String.fromCharCode(byteArray[i]));
+        }
+        return result.join('');
+    }
+
+    /**
+     * Removes the old insertion line the input Intel Hex string contains it.
+     * @param {string} intelHexStr String with the intel hex lines.
+     * @return {string} The Intel Hex string without insertion line.
+     */
+    function cleanseOldHexFormat(intelHexStr) {
+        return intelHexStr.replace(HEX_INSERTION_POINT, '');
+    }
+
+    /**
+     * Parses through an Intel Hex string to find the Python code at the
+     * allocated address and extracts it.
+     * @param {string} intelHexStr - Intel Hex block to scan for the code.
+     * @return {string} Python code.
+     */
+    function extractPyStrFromIntelHex(intelHexStr) {
+        var pyCodeStr = '';
+        var hexFileMemMap = MemoryMap.fromHex(intelHexStr);
+        // Check that the known flash location has user code
+        if (hexFileMemMap.has(USER_CODE_START_ADDR)) {
+            var pyCodeMemMap = hexFileMemMap.slice(USER_CODE_START_ADDR, USER_CODE_LEN);
+            var codeBytes = pyCodeMemMap.get(USER_CODE_START_ADDR);
+            if ((codeBytes[USER_CODE_HEADER_START_B0_INDEX] === USER_CODE_HEADER_START_B0) &&
+                    (codeBytes[USER_CODE_HEADER_START_B1_INDEX] === USER_CODE_HEADER_START_B1)) {
+                pyCodeStr = bytesToStr(codeBytes.slice(USER_CODE_HEADER_SIZE));
+                // Clean null terminators at the end
+                pyCodeStr = pyCodeStr.replace(/\0/g, '');
+            }
+        }
+        return pyCodeStr;
+    }
+
+    /**
+     * Converts the Python code into the Intel Hex format expected by
+     * MicroPython and injects it into a Intel Hex string containing a marker.
+     * @param {string} intelHexStr - Intel Hex block to inject the code.
+     * @param {string} pyStr - Python code string.
+     * @return {string} Intel Hex string with the Python code injected.
+     */
+    function injectPyStrIntoIntelHex(intelHexStr, pyStr) {
+        var codeBytes = strToBytes(pyStr);
+        var blockLength = USER_CODE_HEADER_SIZE + codeBytes.length;
+        // Check the data block fits in the allocated flash area
+        if (blockLength > USER_CODE_LEN) {
+            throw new RangeError('Too long');
+        }
+        // Older DAPLink versions need the last line to be padded
+        blockLength += INTEL_HEX_BYTE_CNT - (blockLength % INTEL_HEX_BYTE_CNT);
+        // The user script block has to start with "MP" marker + script length
+        var blockBytes = new Uint8Array(blockLength);
+        blockBytes[0] = USER_CODE_HEADER_START_B0;
+        blockBytes[1] = USER_CODE_HEADER_START_B1;
+        blockBytes[2] = codeBytes.length & 0xff;
+        blockBytes[3] = (codeBytes.length >> 8) & 0xff;
+        blockBytes.set(codeBytes, USER_CODE_HEADER_SIZE);
+        // Convert to Intel Hex format
+        intelHexStr = cleanseOldHexFormat(intelHexStr);
+        var intelHexMap = MemoryMap.fromHex(intelHexStr);
+        intelHexMap.set(USER_CODE_START_ADDR, blockBytes);
+        // Older versions of DAPLink need the file to end in a new line
+        return intelHexMap.asHexString() + '\n';
+    }
+
+    return {
+        extractPyStrFromIntelHex: extractPyStrFromIntelHex,
+        injectPyStrIntoIntelHex: injectPyStrIntoIntelHex,
+    };
+}());