sc.w

Operands

reg, reg, (reg)

Store conditional (word) : Store t2 as a word at the address in t3 only if that address is still reserved by an lr.w, then set t1 to 0 on success or 1 on failure. Always branch on t1 and retry from the lr.w when it fails

Variants

Store conditional (word) : Store t2 as a word at the address in t3 only if that address is still reserved by an lr.w, then set t1 to 0 on success or 1 on failure. Always branch on t1 and retry from the lr.w when it fails sc.w t1, t2, (t3)

# value is initialized and naturally aligned for this operation.
.data
value: .word 0x12345678
.text
la t0, value
# lr reserves value. The first sc.w succeeds (t2=0); the next has no fresh reservation (t4=1).
li t1, 42
lr.w t3, (t0)
sc.w t2, t1, (t0)
li t1, 99
sc.w t4, t1, (t0)
# t4=1 reports failure; value remains 42 rather than changing to 99.
1
2
3
4
5
6
7
8
9
10
11
12