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)
Summary of Contents for i960 Jx
Page 1: ...Release Date December 1997 Order Number 272483 002 i960 Jx Microprocessor Developer s Manual ...
Page 24: ......
Page 25: ...1 INTRODUCTION ...
Page 26: ......
Page 35: ...2 DATA TYPES AND MEMORY ADDRESSING MODES ...
Page 36: ......
Page 46: ......
Page 47: ...3 PROGRAMMING ENVIRONMENT ...
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Page 73: ...4 CACHE AND ON CHIP DATA RAM ...
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Page 85: ...5 INSTRUCTION SET OVERVIEW ...
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Page 111: ...6 INSTRUCTION SET REFERENCE ...
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Page 233: ...7 PROCEDURE CALLS ...
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Page 256: ......
Page 257: ...8 FAULTS ...
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Page 291: ...9 TRACING AND DEBUGGING ...
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Page 309: ...10 TIMERS ...
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Page 325: ...11 INTERRUPTS ...
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Page 369: ...12 INITIALIZATION AND SYSTEM REQUIREMENTS ...
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Page 413: ...13 MEMORY CONFIGURATION ...
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Page 429: ...14 EXTERNAL BUS ...
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Page 469: ...15 TEST FEATURES ...
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Page 493: ...A CONSIDERATIONS FOR WRITING PORTABLE CODE ...
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Page 503: ...B OPCODES AND EXECUTION TIMES ...
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Page 515: ...C MACHINE LEVEL INSTRUCTION FORMATS ...
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Page 523: ...D REGISTER AND DATA STRUCTURES ...
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Page 551: ...GLOSSARY ...
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Page 561: ...INDEX ...
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