4.8.7 Store S_floating

Format:

STS

Fa.rs,disp.ab(Rb.ab)

!Memory format

Operation:

va {Rbv + SEXT(disp)}

CASE

big_endian_data: va’ va XOR 1002

little_endian_data: va’ va

ENDCASE

(va’)<31:0> Fav<63:62> Fav<58:29>

Exceptions:

Access Violation

Fault on Write

Alignment

Translation Not Valid

Instruction mnemonics:

STS

Store S_floating (Store Longword Integer)

Qualifiers:

None

Description:

STS stores a longword (integer or S_floating) datum from Fa to memory. If the data is not nat- urally aligned, an alignment exception is generated.

The virtual address is computed by adding register Rb to the sign-extended 16-bit displace- ment. For a big-endian longword access, va<2> (bit 2 of the virtual address) is inverted, and any memory management fault is reported for va (not va). The bits of the source operand are fetched from register Fa, the bits are reordered to conform to S_floating memory format, and the result is then written to memory. Bits <61:59> and <28:0> of Fa are ignored. No checking is done.

Instruction Descriptions 4–97

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Compaq ECQD2KCTE manual Store Sfloating, Sts