Data Format Summary; Data Organization In Memory; Data Organization In Registers - Motorola M-CORE MMC2001 Series Reference Manual

2.5 Data Format Summary

The operand data formats supported by the integer unit are standard two's-comple-
ment data formats. The operand size for each instruction is either explicitly encoded
in the instruction (load/store instructions) or implicitly defined by the instruction opera-
tion (index operations, byte extraction). Typically, instructions operate on all 32 bits of
the source operand(s) and generate a 32-bit result.
Memory is viewed from a big-endian byte ordering perspective. The most significant
byte (byte 0) of word 0 is located at address 0. Bits are numbered within a word start-
ing with bit 31 as the most significant bit.
31
Byte 0
Byte 4
Byte 8
Byte C
31
S S S S S S S S S S S S S S S S S S S S S S S S
31
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
31
S S S S S S S S S S S S S S S S
31
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
31
Byte 0
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Byte 1
Byte 5
Byte 9
Byte D
Figure 2-2 Data Organization in Memory
16 15
S
16 15
Byte 1
Figure 2-3 Data Organization in Registers
INTEGER CPU
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Byte 2 Byte 3
Byte 6 Byte 7
Byte A Byte B
Byte E Byte F
8 7
0
S
Byte
8 7 0
Byte
0
Halfword
0
Halfword
0
Byte 2 Byte 3
0
Word at 0
Word at 4
Word at 8
Word at C
Signed Byte
Unsigned Byte
Signed
Halfword
Unsigned
Halfword
Word
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