Altera SerialLite II Protocol - Manual (Page 59)

Altera Corporation 59
SerialLite II Protocol Reference Manual
SerialLite II Specification
Figure 2–37. CRC Alignment for Eight Lanes
Breaking data packets is treated like the end-of-packet as the CRC is
appended to the two byte SUP sequence. The CRC is calculated over that
burst of user data. When the packet is resumed, the initial value used is
the all ones pattern as described below. This allows burst transfers to be
verified before the end-of-packet. As the CRC is computed on each burst
instead of the entire packet, saving of context is not required and the CRC
remainder is discarded making implementation simpler. Having the CRC
computed only over the burst is advantageous for systems using large
packet sizes or susceptible to high bit error rates.
Figure 2–38. SUP Sequence followed by CRC
Time
D8
IDL
D 12
D 16
PD0 PD4
D0 D4
D9
IDL
D 13
PD1 PD5
D1 D5
D 10 D 14
PD2 PD6
D2 D6
D 11 D 15
PD3 PD7
D3 D7
CRC1 CRC2 CRC3 CRC4
EG P1 EG P2 SPP1 SPP2
IDL
EG P1
IDL
EG P2
SDP1
IDL
SDP2
IDL
IDL IDL
IDL IDL IDL
Lane
# 0
Lane
# 1
Lane
# 2
Lane
# 3
Lane
# 4
Lane
# 5
Lane
# 6
Lane
# 7
IDL IDL IDL IDL
IDL IDL IDL IDL
CRC-32
D8
IDL
D 12
D0
D4
D9
IDL
D 13
D1
D5
D 10
SDP1
D 14
D2
D6
D 11
0 0
D 15
D3
D7
D8
SUP1
D 12
D0
D4
D9
0 0
D 13
D1
D5
D 10
SDP1
D 14
D2
D6
D 11
0 1
D 15
D3
D7
SUP1 0 1
CDP1 0 0
D 16 IDL IDL IDL
EG P1 0 0
CDP1 0 1
D 16 IDL IDL IDL
EG P1 0 1
IDL IDL
Lane
# 0
Lane
# 1
Lane
# 2
Lane
# 3
CRC1 CRC2
CRC3 CRC4
CRC1 CRC2
CRC3 CRC4
CRC1 CRC2
CRC3 CRC4
CRC1 CRC2
CRC3 CRC4
Time
Suspended packet
followed by CRC-32
Suspended packet
followed by CRC-32