// Packet format ========================================================

// byte # 0
// 0.7 service bit, 0
// 0.6 destination address presece
// 0.5 source address presece
// 0.4 packet length.4
// 0.3 packet length.3
// 0.2 packet length.2
// 0.1 packet length.1
// 0.0 packet length.0

// [byte # 1]
// 1.7 service bit, 0
// 1.6 destination address.6
// 1.5 destination address.5
// 1.4 destination address.4
// 1.3 destination address.3
// 1.2 destination address.2
// 1.1 destination address.1
// 1.0 destination address.0

// [byte # 2]
// 2.7 service bit, 0
// 2.6 source address.6
// 2.5 source address.5
// 2.4 source address.4
// 2.3 source address.3
// 2.2 source address.2
// 2.1 source address.1
// 2.0 source address.0

// byte # 3
// 3.7 service bit, 0
// 3.6 command.6
// 3.5 command.5
// 3.4 command.4
// 3.3 command.3
// 3.2 command.2
// 3.1 command.1
// 3.0 command.0

// byte # 4..byte # length - 2
// 4.7 service bit, 0
// 4.6 data.6
// 4.5 data.5
// 4.4 data.4
// 4.3 data.3
// 4.2 data.2
// 4.1 data.1
// 4.0 data.0

// byte # 4 + 7
// 11.7 service bit, 0
// 11.6 data6.7
// 11.5 data5.7
// 11.4 data4.7
// 11.3 data3.7
// 11.2 data2.7
// 11.1 data1.7
// 11.0 data0.7

// byte # length - 1
// n-1.7 service bit, 0
// n-1.6 crc7.6
// n-1.5 crc7.5
// n-1.4 crc7.4
// n-1.3 crc7.3
// n-1.2 crc7.2
// n-1.1 crc7.1
// n-1.0 crc7.0

// byte # length
// n.7 service bit, 1
// n.6 service bit, 1
// n.5 service bit, 1
// n.4 service bit, 1
// n.3 service bit, 1
// n.2 service bit, 1
// n.1 service bit, 1
// n.0 service bit, 1

B = 256
N0 = X0*B^0 + X1*B^1 + X2*B^2 + X3*B^3
m0 = X0 + X1 + X2 + X3
M0 = m0 mod (B - 1)
C0 = (m0 - M0) / B

N1 = (N0 - M0) / (B - 1)

N1 = (X0*B^0 + X1*B^1 + X2*B^2 + X3*B^3 - M0) / (B - 1)
N1 = (X0*B^0 + X1*B^1 + X2*B^2 + X3*B^3 - M0) / B / ((B - 1) / B )
N1 = (X1*B^0 + X2*B^1 + X3*B^2 - C0) / ((B - 1) / B )
N1 = (X1*B^0 + X2*B^1 + X3*B^2 - C0) / (1 - 1 / B )
m1 = (X1 + X2 + X3 - C0) / (1 - 1 / B )

// byte # 0
// 0.7 destination address presence
// 0.6 source address presence
// 0.5 stuff bit (babs) / stuff byte presence (cobs-r)
// 0.4 crc size.1
// 0.3 crc size.0
// 0.2 paket id.2
// 0.1 paket id.1
// 0.0 paket id.0

// [byte # 1]
// 1.7 destination address.7
// 1.6 destination address.6
// 1.5 destination address.5
// 1.4 destination address.4
// 1.3 destination address.3
// 1.2 destination address.2
// 1.1 destination address.1
// 1.0 destination address.0

// [byte # 2]
// 2.7 source address.7
// 2.6 source address.6
// 2.5 source address.5
// 2.4 source address.4
// 2.3 source address.3
// 2.2 source address.2
// 2.1 source address.1
// 2.0 source address.0

// byte # 3
// 3.7 command.7
// 3.6 command.6
// 3.5 command.5
// 3.4 command.4
// 3.3 command.3
// 3.2 command.2
// 3.1 command.1
// 3.0 command.0

// [byte # 4]

// 4.7 stuff byte.7
// 4.6 stuff byte.6
// 4.5 stuff byte.5
// 4.4 stuff byte.4
// 4.3 stuff byte.3
// 4.2 stuff byte.2
// 4.1 stuff byte.1
// 4.0 stuff byte.0

// byte # [5..n - 5]
// 5.7 data.7
// 5.6 data.6
// 5.5 data.5
// 5.4 data.4
// 5.3 data.3
// 5.2 data.2
// 5.1 data.1
// 5.0 data.0

// [byte # n - 4]
// n-4.7 crc31 stuff bit
// n-4.6 crc31.30
// n-4.5 crc31.29
// n-4.4 crc31.28
// n-4.3 crc31.27
// n-4.2 crc31.26
// n-4.1 crc31.25
// n-4.0 crc31.24

// [byte # n - 3]
// n-3.7 crc31.23
// n-3.6 crc31.22
// n-3.5 crc31.21
// n-3.4 crc31.20
// n-3.3 crc31.19
// n-3.2 crc31.18
// n-3.1 crc31.17
// n-3.0 crc31.16

// [byte # n - 2]
// n-2.7 crc31.15/crc15 stuff bit
// n-2.6 crc31.14/crc15.14
// n-2.5 crc31.13/crc15.13
// n-2.4 crc31.12/crc15.12
// n-2.3 crc31.11/crc15.11
// n-2.2 crc31.10/crc15.10
// n-2.1 crc31.9/crc15.9
// n-2.0 crc31.8/crc15.8

// [byte # n - 1]
// n-1.7 crc31.7/crc15.7/crc7 stuff bit
// n-1.6 crc31.6/crc15.6/crc7.6
// n-1.5 crc31.5/crc15.5/crc7.5
// n-1.4 crc31.4/crc15.4/crc7.4
// n-1.3 crc31.3/crc15.3/crc7.3
// n-1.2 crc31.2/crc15.2/crc7.2
// n-1.1 crc31.1/crc15.1/crc7.1
// n-1.0 crc31.0/crc15.0/crc7.0

// byte # n
// n.7 stop bit, 1
// n.6 stop bit, 1
// n.5 stop bit, 1
// n.4 stop bit, 1
// n.3 stop bit, 1
// n.2 stop bit, 1
// n.1 stop bit, 1
// n.0 stop bit, 1

#define Bus_resynch 0x00 // 0x00

// Bus_system_command
#define Bus_system_reset 0x10 // H 0x10 C R
#define Bus_system_start 0x11 // H 0x11 C R
#define Bus_system_config 0x12 // H 0x12 C R
#define Bus_system_wakeup 0x13 // H 0x13 C R
#define Bus_system_sleep 0x14 // H 0x14 C R
#define Bus_system_standby 0x15 // H 0x15 C R
#define Bus_system_set_time 0x16 // H 0x16 C-C-C-C T-T-T-T D-D-D-D C R
#define Bus_system_set_bitrate 0x17 // H 0x17 B-B-B-B C R
#define Bus_system_set_address 0x18 // H 0x18 U-U-U-U-U-U-U-U-U-U-U-U-U-U-U-U A C R
#define Bus_system_enumeration 0x19 // H 0x19 M-M-M-M-M-M-M-M-M-M-M-M-M-M-M-M C R

// Bus_pipe_command
#define Bus_pipe_a 0x1A // H 0x1A D..D C R
#define Bus_pipe_b 0x1B // H 0x1B D..D C R
#define Bus_pipe_c 0x1C // H 0x1C D..D C R
#define Bus_pipe_d 0x1D // H 0x1D D..D C R

// Bus_device_command
#define Bus_device_loopback 0x21 // H 0x21 A D..D C R
#define Bus_device_read_config 0x22 // H 0x22 A A-A-A-A C R
#define Bus_device_write_config 0x23 // H 0x23 A A-A-A-A D..D C R
#define Bus_device_simulate_flash 0x24 // H 0x24 A A-A-A-A D..D C R
#define Bus_device_write_flash 0x25 // H 0x25 A A-A-A-A D..D C R
#define Bus_device_check_flash 0x26 // H 0x26 A A-A-A-A D..D C R

#define Bus_user_command_mask 0x40
#define Bus_answer_mask 0x80