Instruction Syntax

Mnemonic	Format	Flags
stfiwx	frS,rA,rB	None

Instruction Encoding

Field	Bits	Description
Primary Opcode	0-5	011111 (0x1F)
frS	6-10	Source floating-point register
rA	11-15	Base register
rB	16-20	Index register
Reserved	21-29	000000000
Reserved	30-31	00

Operation

EA ← (rA) + (rB)
(EA) ← (frS)[32:63]

The effective address is calculated by adding the base register to the index register. The high-order 32 bits of the floating-point register are stored as an integer word at the effective address.

Note: The stfiwx instruction stores the high-order 32 bits of a floating-point register as an integer word to memory. This is useful for accessing the integer representation of floating-point values.

Affected Registers

Memory

• Integer word at effective address (EA)

Examples

Basic Store Floating-Point as Integer

# Store floating-point value as integer word
stfiwx fr1, r3, r4   # Store high 32 bits of fr1 as integer at r3 + r4

Floating-Point to Integer Conversion

# Convert floating-point to integer representation
li r3, buffer        # Load buffer address
li r4, 0             # Index = 0
stfiwx fr1, r3, r4   # Store fr1 as integer word

Bit Manipulation of Floating-Point

# Access floating-point bits as integer
li r3, result        # Load result address
li r4, 0             # Index = 0
stfiwx fr1, r3, r4   # Store high 32 bits of fr1
# Now can manipulate the integer representation

Related Instructions

stfd, stfdx, lfiwax, lfiwzx