add decopression algo and enable data compression

jweismann · Aug 9, 2017 · ef7a045 · ef7a045
1 parent c04190e
commit ef7a045
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Showing 3 changed files with 65 additions and 2 deletions.
diff --git a/lib/drivers/abbott/abbottFreeStyleLibre.js b/lib/drivers/abbott/abbottFreeStyleLibre.js
@@ -92,7 +92,7 @@ export default function (config) {
       progress(0);
 
       const getterFunctions = [
-        cb => { protocol.setCompression(0, cb); },
+        cb => { protocol.setCompression(1, cb); },
         cb => { protocol.getDbSchema(cb); },
         cb => { protocol.getCfgSchema(cb); },
         cb => { protocol.getDateTime(cb); },

diff --git a/lib/drivers/abbott/freeStyleLibreConstants.js b/lib/drivers/abbott/freeStyleLibreConstants.js
@@ -15,6 +15,7 @@ export const COMMAND = {
 export const OP_CODE = {
   GET_DATABASE: 0x31,
   GET_DB_SCHEMA: 0x34,
+  COMPRESSED_DATABASE: 0x35,
   GET_DATE_TIME: 0x41,
   GET_CFG_DATA: 0x51,
   GET_CFG_SCHEMA: 0x54,
@@ -425,6 +426,11 @@ export const RESULT_VALUE_TYPE = {
   SCAN: 2
 };
 
+export const COMPRESSION_TYPE = {
+  UNCOMPRESSED: 0xfd,
+  ZERO_COMPRESSED: 0xff
+}
+
 export const CRC32_TABLE = [
   0x00000000,
   0x04c11db7,

diff --git a/lib/drivers/abbott/freeStyleLibreData.js b/lib/drivers/abbott/freeStyleLibreData.js
@@ -26,7 +26,14 @@ import sundial from 'sundial';
 
 import TZOUtil from '../../TimezoneOffsetUtil';
 
-import {OP_CODE, ERROR_DESCRIPTION, DB_RECORD_TYPE, CFG_TABLE_ID, RESULT_VALUE_TYPE} from './freeStyleLibreConstants';
+import {
+  OP_CODE,
+  ERROR_DESCRIPTION,
+  DB_RECORD_TYPE,
+  CFG_TABLE_ID,
+  RESULT_VALUE_TYPE,
+  COMPRESSION_TYPE
+} from './freeStyleLibreConstants';
 
 const FORMAT = {
   ERROR: 'bb',
@@ -43,6 +50,7 @@ const OP_CODE_PROCESSING_ORDER = [
   //OP_CODE.GET_DB_SCHEMA, // not used for now
   OP_CODE.GET_DATE_TIME,
   OP_CODE.GET_CFG_DATA,
+  OP_CODE.COMPRESSED_DATABASE,
   OP_CODE.GET_DATABASE
 ];
 
@@ -54,6 +62,7 @@ export class FreeStyleLibreData {
     this.opCodeHandlers = {};
     this.opCodeHandlers[OP_CODE.GET_DATE_TIME] = this.handleDateTime.bind(this);
     this.opCodeHandlers[OP_CODE.GET_DB_SCHEMA] = this.handleDatabaseSchema.bind(this);
+    this.opCodeHandlers[OP_CODE.COMPRESSED_DATABASE] = this.handleCompressedDatabase.bind(this);
     this.opCodeHandlers[OP_CODE.GET_DATABASE] = this.handleDatabase.bind(this);
     this.opCodeHandlers[OP_CODE.GET_CFG_SCHEMA] = this.handleConfigSchema.bind(this);
     this.opCodeHandlers[OP_CODE.GET_CFG_DATA] = this.handleConfigData.bind(this);
@@ -226,6 +235,54 @@ export class FreeStyleLibreData {
     }
   }
 
+  handleCompressedDatabase(aapPacket) {
+    let decompressedBuffer = new Buffer(1);
+    let compressedOffset = 0;
+
+    // copy table ID
+    decompressedBuffer[0] = aapPacket.data[compressedOffset];
+    compressedOffset++;
+
+    while (compressedOffset < aapPacket.dataLength) {
+      const blockType = aapPacket.data[compressedOffset];
+      compressedOffset++;
+
+      // parse 24 bit little endian block length
+      let blockLength = aapPacket.data[compressedOffset]
+        | (aapPacket.data[compressedOffset + 1] << 8)
+        | (aapPacket.data[compressedOffset + 2] << 16);
+      compressedOffset += 3;
+
+      blockLength *= 4; // convert number of uint32 values to number of uint8 values
+
+      if (blockType === COMPRESSION_TYPE.UNCOMPRESSED) {
+
+        decompressedBuffer = Buffer.concat(
+          [decompressedBuffer, aapPacket.data.slice(compressedOffset, compressedOffset + blockLength)]);
+        compressedOffset += blockLength;
+
+      } else if (blockType === COMPRESSION_TYPE.ZERO_COMPRESSED) {
+
+        decompressedBuffer = Buffer.concat([decompressedBuffer, Buffer.alloc(blockLength)]);
+        compressedOffset += blockLength;
+
+      } else {
+        debug('handleCompressedDatabase: failed to decompress!');
+        return;
+      }
+    }
+
+    // build decompressed AAP packet to process
+    const decompressedAapPacket = {
+      packetLength: aapPacket.packetLength - aapPacket.dataLength + aapPacket.data.length,
+      data: decompressedBuffer,
+      dataLength: aapPacket.data.length,
+      opCode: OP_CODE.GET_DATABASE
+    };
+
+    this.handleDatabase(decompressedAapPacket);
+  }
+
   handleDatabase(aapPacket) {
     if (aapPacket.dataLength === 0) {
       return;