177
PowerSpan II User Manual
80A1010_MA001_09
Integrated Device Technology
www.idt.com
10. Endian
Mapping
Big-endian refers to a method of formatting data where address 0 (or the smallest address referencing
to the data) points to the most significant byte of the data.
Little-endian refers to a method of formatting data where address 0 (or the smallest address referencing
the data) points to the least significant byte of the data.
Data in a system must be consistent; that is, the system must be entirely big-endian or little-endian.
This chapter describes the endian mapping system used in PowerSpan II. The following topics are
discussed:
•
•
“Processor Bus and PowerSpan II Register Transfers” on page 179
•
“Processor Bus and PCI Transfers” on page 183
10.1
Overview
PowerSpan II supports a flexible endian conversion scheme for the following transactions involving
the Processor Bus (PB) Interface:
•
Access of PowerSpan II registers from the PB Interface
•
Transfers between the processor bus and PCI
—
both externally initiated and PowerSpan II DMA
initiated
10.2
Conventions
illustrates the data bus lanes used to carry each byte of a multi-byte structure on PCI. PCI
stores multi-byte structures with little-endian byte ordering.
No endian conversion is performed for transactions mapped between the two PCI interfaces:
PCI-1 and PCI-2.
Table 46: PCI Byte Lane Definitions
Byte Address
PCI Byte Lanes
AD[2:0]
64-bit Transaction
32-bit Transaction
Lane Number
Pins
AD[2]
Lane Number
Pins
000
0
P1_AD[7:0]
0
0
Px_AD[7:0]
Содержание PowerSpan II
Страница 8: ...Contents 8 PowerSpan II User Manual 80A1010_MA001_09 Integrated Device Technology www idt com ...
Страница 14: ...List of Tables 14 PowerSpan II User Manual 80A1010_MA001_09 Integrated Device Technology www idt com ...
Страница 18: ...About this Document 18 PowerSpan II User Manual 80A1010_MA001_09 Integrated Device Technology www idt com ...
Страница 82: ...2 PCI Interface 82 PowerSpan II User Manual 80A1010_MA001_09 Integrated Device Technology www idt com ...
Страница 112: ...3 Processor Bus Interface 112 PowerSpan II User Manual 80A1010_MA001_09 Integrated Device Technology www idt com ...
Страница 156: ...7 Interrupt Handling 156 PowerSpan II User Manual 80A1010_MA001_09 Integrated Device Technology www idt com ...
Страница 380: ...12 Register Descriptions 380 PowerSpan II User Manual 80A1010_MA001_09 Integrated Device Technology www idt com ...
Страница 394: ...14 Package Information 394 PowerSpan II User Manual 80A1010_MA001_09 Integrated Device Technology www idt com ...
Страница 414: ...15 AC Timing 414 PowerSpan II User Manual 80A1010_MA001_09 Integrated Device Technology www idt com ...
Страница 416: ...16 Ordering Information 416 PowerSpan II User Manual 80A1010_MA001_09 Integrated Device Technology www idt com ...
Страница 420: ...A Hardware Implementation 420 PowerSpan II User Manual 80A1010_MA001_09 Integrated Device Technology www idt com ...
Страница 428: ...B Typical Applications 428 PowerSpan II User Manual 80A1010_MA001_09 Integrated Device Technology www idt com ...
Страница 432: ...Glossary 432 PowerSpan II User Manual 80A1010_MA001_09 Integrated Device Technology www idt com ...