stw
Store Word
stw RS, D(RA)
Stores the low 32 bits of a register to memory.
Details
Store the low 32 bits of RS to the word in memory at the effective address formed by adding the displacement D (sign-extended) to RA, or to the displacement alone if RA is 0. This is a Base category instruction with no status field updates.
Pseudocode Operation
EA ← EXTS(D, 16) + (RA | 0)
MEM(EA, 4) ← RS[32:63]Programming Note
The stw instruction stores the lower 32 bits of a register into memory. Ensure that the destination address is properly aligned to avoid alignment faults. This instruction operates at user privilege level and will raise an exception if the EA is out of bounds or access permissions are violated.
Example
stw r3, 0(r4)
// Store 32-bit word.
Encoding
Binary Layout
36
0
RS
6
RA
11
D
16
Operands
-
RS
Source Register -
D
Displacement -
RA
Base Register