13. PCI Controller (PCIC)

Rev.1.00 Jan. 10, 2008 Page 644 of 1658

REJ09B0261-0100

(6) Endian This LSI supports both the big and little endian formats. Since the PCI local bus is inherently little endian, the PCIC supports both byte swapping and non-byte swapping. The endian format is specified by the TBS bit in PCICR.
31
MSB LSB
0
PCI bus data
SHwy data
1. Little endian
A' B' C' D' ABC
A' B' C' D' ABCD
A B C
PCI_Addr[2] = 1
PCI_Addr[2] = 0
31
MSB LSB
0
PCI bus data
SHwy
data
AB C D A' B' C' D'
A B C D A' B' C' D'
A B C
PCI_Addr[2] = 0
PCI_Addr[2] = 1
2. Big endian
Note: PCIAddr[2]: PCI bus AD[2]
D
D
Buffer data
Buffer data
D
Figure 13.13 Endian Conversion from PCI Bus to SuperHyway Bus (Non-Byte Swapping: TBS = 0)