10. Endian Mapping
181
PowerSpan II User Manual
80A1010_MA001_09
Integrated Device Technology
www.idt.com
In PowerPC little-endian mode, the processor munges the address and places the scalar on the external
byte lanes starting at this modified address. The scalar is still in big-endian order. This operation is only
defined for starting addresses that are a multiple of the size of the scalar. In PowerPC literature, this is
referred to as being naturally aligned.
The munging performed by the processor is illustrated in
.
When the processor bus is operating in PowerPC little-endian mode, END bit must be set to PowerPC
little-endian mode. In this case, the PB Slave munges the processor bus address, and maps byte lanes to
register addresses to preserve the significance of the scalar.
Ti
p
Munging the address makes the address appear to the processor bus that individual aligned
scalars are stored as little-endian values when they are actually stored in big-endian order.
They are stored at different byte addresses with a double word.
Table 49: Processor Bus
Address Munging
Transfer Size
Address modification
4 bytes
XOR with 0b100
2 bytes
XOR with 0b110
1 byte
XOR with 0b111
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 ...