Table 2-24. Floating-Point Store Instructions; Table 2-25. Store Floating-Point Single Behavior; Table 2-26. Store Floating-Point Double Behavior - IBM PowerPC 750GX User Manual

Table 2-24 summarizes the single-precision and double-precision floating-point store and stfiwx instructions.

Table 2-24. Floating-Point Store Instructions

Name
Store Floating-Point Single
Store Floating-Point Single Indexed
Store Floating-Point Single with Update
Store Floating-Point Single with Update Indexed
Store Floating-Point Double
Store Floating-Point Double Indexed
Store Floating-Point Double with Update
Store Floating-Point Double with Update Indexed
Store Floating-Point as Integer Word Indexed
1. The stfiwx instruction is optional in the PowerPC Architecture.
Some floating-point store instructions require conversions in the LSU. Table 2-25 shows conversions the LSU
makes when executing a Store Floating-Point Single instruction.

Table 2-25. Store Floating-Point Single Behavior

FPR Precision
Single
Single
Single
Single
Double
Double
Double
Double
Note: The FPRs are not initialized by HRESET, and they must be initialized with some valid value after POR
HRESET and before being stored.
Table 2-26 shows the conversions made when performing a Store Floating-Point Double instruction. Most
entries in the table indicate that the floating-point value is simply stored. Only in a few cases are any other
actions taken.

Table 2-26. Store Floating-Point Double Behavior

FPR Precision
Single
Single
Single
gx_02.fm.(1.2)
March 27, 2006
IBM PowerPC 750GX and 750GL RISC Microprocessor
Mnemonic
1
Data Type
Normalized
Denormalized
Zero, infinity, QNaN
SNaN
Normalized
Denormalized
Zero, infinity, QNaN
SNaN
(Page 1 of 2)
Data Type
Normalized
Denormalized
Zero, infinity, QNaN
stfs
stfsx
stfsu
stfsux
stfd
stfdx
stfdu
stfdux
stfiwx
If (exp ð ≤ 896)
then Denormalize and Store
Normalize and Store
User's Manual
Syntax
frS,d(rA)
frS,rB
frS,d(rA)
frS,rB
frS,d(rA)
frS,rB
frS,d(rA)
frS,rB
frS,rB
Action
Store
Store
Store
Store
else
Store
Store zero
Store
Store
Action
Store
Store
Programming Model
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