SUBX8 — Subtract with Shift by 3

Instruction Word

Slot
ae2_slot0
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 ae_format2 - 64 bit(s)0000 1110
SUBX8 1000000000001101 1101
r 3210
s 3210
t 3210

Slot
ae_slot0
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 ae_format - 64 bit(s) 1111
SUBX8 01011101
r 3210
s 3210
t 3210

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
SUBX8 11110000 0000
r 3210
s 3210
t 3210

Slot
ae_slot0
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 ae_format1 - 64 bit(s)1 1110
SUBX8 01011101
r 3210
s 3210
t 3210

Assembler Syntax

SUBX8 ar, as, at

C Syntax

#include <xtensa/tie/xt_core.h>

extern int XT_SUBX8(int s, int t);

Description

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

SUBX8 calculates the two's complement 32-bit difference of address register as shifted left by three bits and address register at. The low 32 bits of the difference are written to address register ar. Arithmetic overflow is not detected.

SUBX8 is frequently used as part of sequences to multiply by small constants.

Operation

AR[r] ← (AR[s]28..0||03) − AR[t]

Exceptions

EveryInstR Group (see EveryInstR Group:)

Implementation Pipeline

In Out
ars Estage, art Estage arr Estage

Protos that use SUBX8

proto SUBX8 { out int32 r, in int32 s, in int32 t }{}{
SUBX8 r, s, t;
}