Implement a QRCode payload generator

src/Makefile

@@ -1,6 +1,6 @@
 TOPTARGETS := all clean check
 
-SUBDIRS = lwip system lib/core lib/support ble inet
+SUBDIRS = lwip system lib/core lib/support ble inet setup_payload
 
 $(TOPTARGETS): $(SUBDIRS)
 $(SUBDIRS):

src/setup_payload/Makefile

@@ -0,0 +1,29 @@
+TOP_DIR = ../..
+Test_Dir = tests
+
+.PHONY: all clean check
+
+all: libqr.a check
+
+include $(TOP_DIR)/.yams/cpp_rules.min
+
+Module_Includes = \
+	-I. \
+	-I$(TOP_DIR)/src/include \
+	-I$(TOP_DIR)/src/lib/ \
+	-I$(TOP_DIR)/build/config/standalone/
+
+Module_Test_Includes = $(Module_Includes)
+
+CPP_Files = \
+	SetupCodeUtils.cpp \
+	SetupPayload.cpp \
+	QRCodeSetupPayloadGenerator.cpp \
+
+libqr.a: $(CPP_Objects)
+	ar rvs $@ $^
+	@echo "LINK =>  $@"
+
+clean: my_clean
+	@rm -f libqr.a *.gcda *.gcno *.gcov
+

src/setup_payload/QRCodeSetupPayloadGenerator.cpp

@@ -0,0 +1,189 @@
+/*
+ *
+ *    <COPYRIGHT>
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+
+/**
+ *    @file
+ *      This file implements a QRCode Setup Payload generator in accordance
+ *      with the CHIP specification.
+ *
+ */
+
+#include "QRCodeSetupPayloadGenerator.h"
+#include "SetupCodeUtils.h"
+
+#include <iostream>
+#include <vector>
+
+#include <stdlib.h>
+
+using namespace chip;
+using namespace std;
+
+void QRCodeSetupPayloadGenerator::resetBitSet()
+{
+    mPayloadBitsIndex = kTotalPayloadDataSizeInBits;
+    mPayloadBits.reset();
+}
+
+// Populates numberOfBits starting from LSB of input into mPayloadBits
+void QRCodeSetupPayloadGenerator::populateInteger(uint64_t input, size_t numberOfBits)
+{
+    if (mPayloadBitsIndex < numberOfBits || input >= 1 << numberOfBits)
+    {
+        abort();
+    }
+    mPayloadBitsIndex -= numberOfBits;
+    int currentIndex = mPayloadBitsIndex;
+
+    int endIndex = currentIndex + (numberOfBits - 1);
+
+    while (currentIndex <= endIndex)
+    {
+        input & 1 ? mPayloadBits.set(currentIndex) : mPayloadBits.reset(currentIndex);
+        currentIndex++;
+        input /= 2;
+    }
+}
+
+void QRCodeSetupPayloadGenerator::populateVersion()
+{
+    populateInteger(mPayload.version, kVersionFieldLengthInBits);
+}
+
+void QRCodeSetupPayloadGenerator::populateVendorID()
+{
+    populateInteger(mPayload.vendorID, kVendorIDFieldLengthInBits);
+}
+
+void QRCodeSetupPayloadGenerator::populateProductID()
+{
+    populateInteger(mPayload.productID, kProductIDFieldLengthInBits);
+}
+
+void QRCodeSetupPayloadGenerator::populateCustomFlowRequiredField()
+{
+    populateInteger(mPayload.requiresCustomFlow, kCustomFlowRequiredFieldLengthInBits);
+}
+
+void QRCodeSetupPayloadGenerator::populateRendezvousInfo()
+{
+    populateInteger(mPayload.rendezvousInformation, kRendezvousInfoFieldLengthInBits);
+}
+
+void QRCodeSetupPayloadGenerator::populateDiscriminator()
+{
+    populateInteger(mPayload.discriminator, kPayloadDiscriminatorFieldLengthInBits);
+}
+
+void QRCodeSetupPayloadGenerator::populateSetupPIN()
+{
+    populateInteger(mPayload.setUpPINCode, kSetupPINCodeFieldLengthInBits);
+}
+
+void QRCodeSetupPayloadGenerator::populateReservedField()
+{
+    populateInteger(0, kReservedFieldLengthInBits);
+}
+
+void QRCodeSetupPayloadGenerator::generateBitSet()
+{
+    resetBitSet();
+    populateVersion();
+    populateVendorID();
+    populateProductID();
+    populateCustomFlowRequiredField();
+    populateRendezvousInfo();
+    populateDiscriminator();
+    populateSetupPIN();
+    populateReservedField();
+}
+
+string QRCodeSetupPayloadGenerator::payloadBinaryRepresentation()
+{
+    if (mPayload.isValid())
+    {
+        generateBitSet();
+        return mPayloadBits.to_string();
+    }
+    return string();
+}
+
+// This function assumes bits.size() % 8 == 0
+// TODO: Can this method be written in a more elegant way?
+vector<uint16_t> arrayFromBits(bitset<kTotalPayloadDataSizeInBits> bits)
+{
+    vector<uint16_t> resultVector;
+    size_t numberOfBits  = bits.size();
+    size_t numberOfBytes = numberOfBits / 8;
+    bool oddNumOfBytes   = (numberOfBytes % 2) ? true : false;
+
+    // Traversing in reverse, hence startIndex > endIndex
+    int endIndex   = 0;
+    int startIndex = bits.size() - 1;
+
+    /*
+    Every 2 bytes (16 bits) of binary source data are encoded to 3 characters of the Base-45 alphabet.
+    If an odd number of bytes are to be encoded, the remaining single byte will be encoded
+    to 2 characters of the Base-45 alphabet.
+    */
+    if (oddNumOfBytes)
+    {
+        endIndex = 8;
+    }
+
+    while (startIndex > endIndex)
+    {
+        int currentIntegerIndex = startIndex;
+        uint16_t result         = 0;
+        for (int i = currentIntegerIndex; i > currentIntegerIndex - 16; i--)
+        {
+            result = result << 1;
+            result = result | bits.test(i);
+        }
+        resultVector.push_back(result);
+        startIndex -= 16;
+    }
+
+    // If we have odd number of bytes append the last byte.
+    if (oddNumOfBytes)
+    {
+        uint16_t result = 0;
+        for (int i = 7; i >= 0; i--)
+        {
+            result = result << 1;
+            result = result & bits.test(i);
+        }
+        resultVector.push_back(result);
+    }
+    return resultVector;
+}
+
+string QRCodeSetupPayloadGenerator::payloadBase45Representation()
+{
+    if (mPayload.isValid())
+    {
+        generateBitSet();
+        vector<uint16_t> integerArray = arrayFromBits(mPayloadBits);
+        string result;
+        for (int idx = 0; idx < integerArray.size(); idx++)
+        {
+            result += base45EncodedString(integerArray[idx], 3);
+        }
+        return result;
+    }
+    return string();
+}

src/setup_payload/QRCodeSetupPayloadGenerator.h

@@ -0,0 +1,69 @@
+/*
+ *
+ *    <COPYRIGHT>
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+
+/**
+ *    @file
+ *      This file describes a QRCode Setup Payload generator based on the
+ *      CHIP specification.
+ *
+ *      The encoding of the binary data to a base45 string is as follows:
+ *      - Every 2 bytes (16 bits) of binary source data are encoded to 3
+ *        characters of the Base-45 alphabet.
+ *      - If an odd number of bytes are to be encoded, the remaining
+ *        single byte is encoded to 2 characters of the Base-45 alphabet.
+ */
+
+#include "SetupPayload.h"
+
+#include <bitset>
+#include <string>
+using namespace std;
+
+#ifndef _QR_CODE_SETUP_PAYLOAD_GENERATOR_
+#define _QR_CODE_SETUP_PAYLOAD_GENERATOR_
+
+namespace chip {
+
+class QRCodeSetupPayloadGenerator
+{
+private:
+    bitset<kTotalPayloadDataSizeInBits> mPayloadBits;
+    SetupPayload mPayload;
+    // points to the current index within the bitset
+    int mPayloadBitsIndex;
+
+    void populateInteger(uint64_t input, size_t numberOfBits);
+    void populateVersion();
+    void populateVendorID();
+    void populateProductID();
+    void populateCustomFlowRequiredField();
+    void populateRendezvousInfo();
+    void populateDiscriminator();
+    void populateSetupPIN();
+    void populateReservedField();
+    void resetBitSet();
+    void generateBitSet();
+
+public:
+    string payloadBinaryRepresentation();
+    string payloadBase45Representation();
+    QRCodeSetupPayloadGenerator(SetupPayload setupPayload) : mPayload(setupPayload){};
+};
+
+}; // namespace chip
+
+#endif /* _QR_CODE_SETUP_PAYLOAD_GENERATOR_ */

src/setup_payload/SetupCodeUtils.cpp

@@ -0,0 +1,57 @@
+/*
+ *
+ *    <COPYRIGHT>
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+
+/**
+ *    @file
+ *      This file implements converting an input into a Base45 String
+ *
+ */
+
+#include "SetupCodeUtils.h"
+
+#include <string>
+#include <algorithm>
+
+using namespace std;
+
+namespace chip {
+
+char base45CharacterSet[45] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E',
+                                'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
+                                'U', 'V', 'W', 'X', 'Y', 'Z', ' ', '$', '%', '*', '+', '-', '.', '/', ':' };
+
+string base45EncodedString(uint64_t input, size_t minLength)
+{
+    string result;
+    int radix = 45;
+    do
+    {
+        char base45char = base45CharacterSet[input % radix];
+        result += base45char;
+        input = input / radix;
+    } while (input != 0);
+
+    while (result.length() < minLength)
+    {
+        result.append("0");
+    }
+
+    reverse(result.begin(), result.end());
+    return result;
+}
+
+} // namespace chip

src/setup_payload/SetupCodeUtils.h

@@ -0,0 +1,37 @@
+/*
+ *
+ *    <COPYRIGHT>
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+
+/**
+ *    @file
+ *      Utility header to encode an input into a Base45 String
+ */
+
+#ifndef _SETUP_CODE_UTILS_H_
+#define _SETUP_CODE_UTILS_H_
+
+#include <string>
+#include <stdint.h>
+
+using namespace std;
+
+namespace chip {
+
+std::string base45EncodedString(uint64_t input, size_t minLength);
+
+} // namespace chip
+
+#endif /* _SETUP_CODE_UTILS_H_ */