Floating-Point Store Instructions - IBM PowerPC 604 User Manual

Implementation Notes-The following notes characterize how the 604 treats exceptions:
• On the 604, if a floating-point number is not aligned on a word boundary, an
alignment exception occurs.
• The floating-point load and store indexed instructions (lfsx, lfsux, lfdx, lfdux, stfsx,
stfsux, stfdx, stf dux) are invalid when the Re bit is one. In the 604, executing one
of these invalid instruction forms causes CRO to be set to an undefined value.
Note that the PowerPC architecture defines load with update instructions with r A= 0 as an
invalid form.
Table 2·25. Floatlng-Polnt Load Instructions
Name Mnemonic Operand Syntax
Load Floating-Point Single
Hs frD,d(rA)
Load Floating-Point Single Indexed lfsx frD,rA,rB
Load Floating-Point Single with Update lfsu frD,d(rA)
Load Floating-Point Single with Update Indexed
lfsux frD,rA,rB
Load Floating-Point Double ltd frD,d(rA)
Load Floating-Point Double Indexed
lfdx frD,rA,rB
Load Floating-Point Double with Update
lfdu frD,d(rA)
Load Floating-Point Double with Update Indexed
lfdux frD,rA,rB
2.3.4.3.9 Floating-Point Store Instructions
This section describes floating-point store instructions. There are three basic forms of the
store instruction-single-precision, double-precision, and integer. The integer form is
supported by the optional stfiwx instruction. Because the FPRs support only floating-point,
double-precision format for floating-point data, single-precision floating-point store
instructions convert double-precision data to single-precision format before storing the
operands. Table 2-26 summarizes the floating-point store instructions.
Table 2-26. Floating-Point Store Instructions
Name
Mnemonic Operand Syntax
Store Floating-Point Single stls frS,d(rA)
Store Floating-Point Single Indexed stlsx frS,r B
Store Floating-Point Single with Update stlsu frS,d(rA)
Store Floating-Point Single
with
Update Indexed
stlsux
frS,r B
Store Floating-Point Double stld frS,d(rA)
Store Floating-Point Double Indexed Stfdx frS,rB
Store Floating-Point Double with Update
stldu frS,d(rA)
Chapter 2. PowerPC 604 Processor Programming Model 2-41
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