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Appendix B. Bit and Byte Ordering
B-5
Little-Endian Mode
If the data is stored to the PCI memory space, it appears as shown in Figure B-3.
Figure B-3. Big-Endian Memory Image in Big-Endian PCI Memory Space
Note that the string ‘hello, world’ starts at address 0x000. The other data is stored to the
desired location with big-endian byte ordering.
B.4 Little-Endian Mode
When the processor core is operating in little-endian mode, its internal BIU modifies each
address. This modification is called munging. The processor munges the address by
exclusive-ORing (XOR) the three low-order address bits with a three-bit value that depends
on the length of the operand (1, 2, 4, or 8 bytes), as shown in Table B-2.
Contents
‘l’
‘l’
‘e’
‘h’
Address
03
02
01
00
Contents
‘w’
‘ ’
‘,’
‘o’
Address
07
06
05
04
Contents
‘d’
‘l’
‘r’
‘o’
Address
0B
0A
09
08
Contents
34
12
0x55
0x00
Address
0F
0E
0D
0C
Contents
0x98
0xBA
0xDC
0xFE
Address
13
12
11
10
Contents
Address
17
16
15
14
Содержание MPC8240
Страница 1: ...MPC8240UM D Rev 1 1 2001 MPC8240 Integrated Processor User s Manual ...
Страница 38: ...xviii MPC8240 Integrated Processor User s Manual TABLES Table Number Title Page Number ...
Страница 48: ...xlviii MPC8240 Integrated Processor User s Manual Acronyms and Abbreviations ...
Страница 312: ...6 94 MPC8240 Integrated Processor User s Manual ROM Flash Interface Operation ...
Страница 348: ...7 36 MPC8240 Integrated Processor User s Manual PCI Host and Agent Modes ...
Страница 372: ...8 24 MPC8240 Integrated Processor User s Manual DMA Register Descriptions ...
Страница 394: ...9 22 MPC8240 Integrated Processor User s Manual I2O Interface ...
Страница 412: ...10 18 MPC8240 Integrated Processor User s Manual Programming Guidelines ...
Страница 454: ...12 14 MPC8240 Integrated Processor User s Manual Internal Arbitration ...
Страница 466: ...13 12 MPC8240 Integrated Processor User s Manual Exception Latencies ...
Страница 516: ...16 14 Watchpoint Trigger Applications ...
Страница 538: ...B 16 MPC8240 Integrated Processor User s Manual Setting the Endian Mode of Operation ...
Страница 546: ...C 8 MPC8240 Integrated Processor User s Manual ...
Страница 640: ...INDEX Index 16 MPC8240 Integrated Processor User s Manual ...