Revision 5.01 – November 30, 2005
S5335 – PCI Bus Controller, 3.3V
Data Sheet
64-Bit Endian Conversion
the FIFO first. INTCSR D31:30 identify which method
is used by the application. These bits toggle after each
32-bit operation to indicate if half or all of a 64-bit data
operation has been completed. The initial state of
these bits establishes the loading and emptying order
for 64-bit data during operation.
Because the S5335 interfaces to a 32-bit PCI bus,
special operation is required to handle 64-bit data
endian conversion. Figure 76 shows 64-bit endian
conversion. The S5335 must know whether the lower
32-bits enter the FIFO first or the upper 32-bits enter
Figure 76. 64-bit Endian Conversion
DESTINATION
D 31-24
SLR
D 23-16 D 15-8
D 7-0
SLR
READ ORDER:
BYTES 3-0 FIRST
OR
BYTES 7-4 FIRST
SEE TEXT
SLR
SLR
BYTE 7
BYTE 6
BYTE 3
BYTE 2
BYTE 5
BYTE 1 BYTE 0
BYTE 4
BYTE 6
BYTE 2
BYTE 7
BYTE 5
BYTE 3
BYTE 1
BYTE 4
BYTE 0
LOAD ORDER:
BYTES 3-0 FIRST
OR,
BYTES 7-4 FIRST
SEE TEXT
D 31-24
SOURCE
D 15-8
D 7-0
D 23-16
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