DATA TYPES AND MEMORY ADDRESSING MODES
2-5
2
For example,
Table 2-1
shows eight bytes of data in memory.
Table 2-2
shows the differences
between little and big endian accesses for byte, short, word and long-word data.
Figure 2-2
shows
the resultant data placement in registers.
Once data is read into registers, byte order is no longer relevant. The lowest significant bit is
always bit 0. The most significant bit is always bit 31 for words, bit 15 for short words, and bit 7
for bytes.
Byte ordering affects the way the i960 Jx processor handles bus accesses. See
section 13.6.2,
“Selecting the Byte Order” (pg. 13-12)
for more information.
Table 2-1. Memory Contents for Little and Big Endian Example
ADDRESS
DATA
1000H
12H
1001H
34H
1002H
56H
1003H
78H
1004H
9AH
1005H
BCH
1006H
DEH
1007H
F0H
Table 2-2. Byte Ordering for Little and Big Endian Accesses
Access
Example
Register Contents
(Little Endian)
Register Contents
(Big Endian)
Byte at 1000H
ldob 0x1000, r3
12H
12H
Short at 1002H
ldos 0x1002, r3
7856H
5678H
Word at 1000H
ld
0x1000, r3
78563412H
12345678H
Long-Word at 1000H
ldl
0x1000, r4
78563412H (r4)
F0DEBC9AH (r5)
12345678H (r4)
9ABCDEF0H (r5)
Содержание i960 Jx
Страница 1: ...Release Date December 1997 Order Number 272483 002 i960 Jx Microprocessor Developer s Manual ...
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Страница 25: ...1 INTRODUCTION ...
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Страница 35: ...2 DATA TYPES AND MEMORY ADDRESSING MODES ...
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Страница 47: ...3 PROGRAMMING ENVIRONMENT ...
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Страница 73: ...4 CACHE AND ON CHIP DATA RAM ...
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Страница 85: ...5 INSTRUCTION SET OVERVIEW ...
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Страница 111: ...6 INSTRUCTION SET REFERENCE ...
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Страница 195: ...INSTRUCTION SET REFERENCE 6 83 6 Opcode mov 5CCH REG movl 5DCH REG movt 5ECH REG movq 5FCH REG See Also LOAD STORE lda ...
Страница 233: ...7 PROCEDURE CALLS ...
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Страница 257: ...8 FAULTS ...
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Страница 291: ...9 TRACING AND DEBUGGING ...
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Страница 309: ...10 TIMERS ...
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Страница 325: ...11 INTERRUPTS ...
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Страница 369: ...12 INITIALIZATION AND SYSTEM REQUIREMENTS ...
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Страница 413: ...13 MEMORY CONFIGURATION ...
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Страница 429: ...14 EXTERNAL BUS ...
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Страница 469: ...15 TEST FEATURES ...
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Страница 493: ...A CONSIDERATIONS FOR WRITING PORTABLE CODE ...
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Страница 503: ...B OPCODES AND EXECUTION TIMES ...
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Страница 515: ...C MACHINE LEVEL INSTRUCTION FORMATS ...
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Страница 523: ...D REGISTER AND DATA STRUCTURES ...
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Страница 551: ...GLOSSARY ...
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Страница 561: ...INDEX ...
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