S32RI — Store 32-bit Release

Instruction Word

Slot
Inst
6
3
6
2
6
1
6
0
5
9
5
8
5
7
5
6
5
5
5
4
5
3
5
2
5
1
5
0
4
9
4
8
4
7
4
6
4
5
4
4
4
3
4
2
4
1
4
0
3
9
3
8
3
7
3
6
3
5
3
4
3
3
3
2
3
1
3
0
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
1
9
1
8
1
7
1
6
1
5
1
4
1
3
1
2
1
1
1
0
9876543210
Format x24 - 24 bit(s) 0
S32RI 1111 0010
t 3210
s 3210
imm8 76543210

Assembler Syntax

S32RI at, as, 0..1020

C Syntax

#include <xtensa/tie/xt_sync.h>

extern void XT_S32RI(unsigned c, unsigned * p, immediate o);

Description

(please consult the Xtensa ® Instruction Set Architecture Reference Manual for any cross references and additional information)

S32RI is a store barrier and 32-bit store from address register at to memory. S32RI stores to synchronization variables, which signals that previously written data is "released" for consumption by readers of the synchronization variable. This store will not perform until all previous loads, stores, acquires, and releases have performed. This ensures that any loads of the synchronization variable that see the new value will also find all previously written data available as well.

S32RI forms a virtual address by adding the contents of address register as and an
8-bit zero-extended constant value encoded in the instruction word shifted left by two. Therefore, the offset can specify multiples of four from zero to 1020. S32RI waits for previous loads, stores, acquires, and releases to be performed, and then the data to be stored is taken from the contents of address register at and written to memory at the physical address. Because the method of waiting is implementation dependent, this is indicated in the operation section below by the implementation function release.

If the Region Translation Option or the MMU Option is enabled, the virtual address is translated to the physical address. If not, the physical address is identical to the virtual address. If the translation or memory reference encounters an error (for example, protection violation or non-existent memory), the processor raises one of several exceptions .

Without theUnaligned Exception Option , the two least significant bits of the address are ignored. A reference to an address that is not 0 mod 4 produces the same result as a reference to the address with the least significant bits cleared. With the Unaligned Exception Option, such an access raises an exception.

Operation

vAddr ← AR[s] + (022||imm8||02)
release
Store32 (vAddr, AR[t])

Exceptions

Memory Store Group (see Memory Store Group:)

Implementation Pipeline

In Out
art Mstage, ars Estage

Protos that use S32RI

proto S32RI { in uint32 c, in uint32 * p, in immediate o }{}{
S32RI c, p, o + 0;
}