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Basic Architecture 2–11
Figure 2–17: X_floating Big-Endian Datum
Figure 2–18: X_floating Big-Endian Register Format
2.2.7 Longword Integer Format in Floating-Point Unit
A longword integer operand occupies 32 bits in memory, arranged as shown in Figure 2–19.
Figure 2–19: Longword Integer Datum
A longword integer operand occupies 64 bits in a floating register, arranged as shown in Fig-
ure 2–20.
Figure 2–20: Longword Integer Floating-Register Format
There is no explicit longword load or store instruction; the S_floating load/store instructions
are used to move longword data into or out of the floating registers. The register bits <61:59>
are set by the S_floating load exponent mapping. They are ignored by S_floating store. They
are also ignored in operands of a longword integer operate instruction, and they are set to 000
in the result of a longword operate instruction.
The register format bit <62> "I" in Figure 2–20 is part of the Integer field in Figure 2–19 and
represents the high-order bit of that field.
15
S Exponent Fraction_high
Fraction_low
0
A+8:
A:
Byte
Byte
0 15
S Exponent Fraction_high Fraction_low
Fn OR 1 Fn
Byte Byte
S
Integer :A
0
3031
063 62
S
59 58
29 28
xxx Integer 0 :Fx
61
I