Adds functions to generate paged-mode programming packets. (#500)

src/dcc/Packet.cxx

@@ -82,6 +82,9 @@ enum
     DCC_SVC_BITVAL_VERIFY = 0b11100000,
     DCC_SVC_BITVAL_VALUE = 0b00001000,
 
+    DCC_SVC_PAGED_WRITE = 0b01111000,
+    DCC_SVC_PAGED_VERIFY = 0b01110000,
+
     DCC_BASIC_ACCESSORY_B1 = 0b10000000,
     DCC_BASIC_ACCESSORY_B2 = 0b10000000,
 
@@ -293,6 +296,24 @@ void Packet::set_dcc_svc_write_bit(
     add_dcc_prog_command(DCC_SVC_BIT_MANIPULATE, cv_number, vvv);
 }
 
+void Packet::set_dcc_svc_paged_write_reg(uint8_t reg, uint8_t value)
+{
+    HASSERT(reg < 8);
+    start_dcc_svc_packet();
+    payload[dlc++] = DCC_SVC_PAGED_WRITE | reg;
+    payload[dlc++] = value;
+    add_dcc_checksum();
+}
+
+void Packet::set_dcc_svc_paged_verify_reg(uint8_t reg, uint8_t value)
+{
+    HASSERT(reg < 8);
+    start_dcc_svc_packet();
+    payload[dlc++] = DCC_SVC_PAGED_VERIFY | reg;
+    payload[dlc++] = value;
+    add_dcc_checksum();
+}
+
 void Packet::add_dcc_basic_accessory(unsigned address, bool is_activate) {
     payload[dlc++] = DCC_BASIC_ACCESSORY_B1 | ((address >> 3) & 0b111111);
     uint8_t b2 = 1;

src/dcc/Packet.cxxtest

@@ -22,6 +22,17 @@ protected:
         return vector<uint8_t>(pkt_.payload + 0, pkt_.payload + pkt_.dlc);
     }
 
+    /// @return true if pkt_ has correct checksum.
+    bool check_checksum()
+    {
+        uint8_t p = 0;
+        for (unsigned i = 0; i < pkt_.dlc; i++)
+        {
+            p ^= pkt_.payload[i];
+        }
+        return p == 0;
+    }
+
     vector<uint8_t> packet(const std::initializer_list<int> &data)
     {
         vector<uint8_t> v;
@@ -205,6 +216,31 @@ TEST_F(PacketTest, SvcProgDirectBit)
     EXPECT_THAT(get_packet(), ElementsAre(b1, b2, b3, b1 ^ b2 ^ b3));
 }
 
+TEST_F(PacketTest, SvcProgPagedWrite)
+{
+    pkt_.set_dcc_svc_paged_set_page();
+    EXPECT_THAT(get_packet(), ElementsAre(0b01111101, 0b00000001, 0b01111100));
+    EXPECT_TRUE(pkt_.packet_header.send_long_preamble);
+    EXPECT_TRUE(check_checksum());
+
+    pkt_.set_dcc_svc_paged_write_reg(3, 0xaa);
+    EXPECT_THAT(get_packet(), ElementsAre(0b01111011, 0xaa, _));
+    EXPECT_TRUE(check_checksum());
+}
+
+TEST_F(PacketTest, SvcProgPagedVerify)
+{
+    pkt_.set_dcc_svc_paged_set_page(55);
+    EXPECT_THAT(get_packet(), ElementsAre(0b01111101, 55, _));
+    EXPECT_TRUE(pkt_.packet_header.send_long_preamble);
+    EXPECT_TRUE(check_checksum());
+
+    pkt_.set_dcc_svc_paged_verify_reg(0, 0x34);
+    EXPECT_THAT(get_packet(), ElementsAre(0b01110000, 0x34, _));
+    EXPECT_TRUE(pkt_.packet_header.send_long_preamble);
+    EXPECT_TRUE(check_checksum());
+}
+
 TEST_F(PacketTest, MMOld)
 {
     pkt_.start_mm_packet();

src/dcc/Packet.hxx

@@ -57,6 +57,9 @@ struct Packet : public DCCPacket
      * for marklin-14-step speed commands. */
     static const unsigned CHANGE_DIR = DCC_PACKET_EMERGENCY_STOP;
 
+    /** Used for page-preset packets. */
+    static const unsigned PAGE_REGISTER_ID = 0b101;
+
     Packet()
     {
         clear();
@@ -230,6 +233,35 @@ struct Packet : public DCCPacket
      * @param desired is true if bit:=1 should be written */
     void set_dcc_svc_write_bit(unsigned cv_number, unsigned bit, bool desired);
 
+    /** Sets the packet to a DCC service mode packet in Paged Mode, setting the
+     * page register. This function does not need a DCC address.  Includes the
+     * checksum.
+     * @param page Page to set, 1 is the default page, zero is reserved, 255
+     * max.
+     */
+    void set_dcc_svc_paged_set_page(unsigned page = 1)
+    {
+        set_dcc_svc_paged_write_reg(PAGE_REGISTER_ID, page);
+    }
+
+    /** Sets the packet to a DCC service mode packet in Paged Mode, setting any
+     * register. This function does not need a DCC address.  Includes the
+     * checksum.
+     * @param reg register, 0 to 7. On the default page register 0 is CV1
+     * (address).
+     * @param value Payload to write to that register. 0 to 255.
+     */
+    void set_dcc_svc_paged_write_reg(uint8_t reg, uint8_t value);
+
+    /** Sets the packet to a DCC service mode packet in Paged Mode, setting the
+     * page register. This function does not need a DCC address.  Includes the
+     * checksum.
+     * @param reg register, 0 to 7. On the default page register 0 is CV1
+     * (address).
+     * @param value Payload to check on that register.
+     */
+    void set_dcc_svc_paged_verify_reg(uint8_t reg, uint8_t value);
+
     /** Adds a DCC basic accessory decoder command packet and the checksum
      * byte.
      * @param address is the unencoded 12-bit address, containing both the A