AE_LB — bitstream lookahead, returning 1 to 16 bits based on AR register

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
AE_LB 01101001 0010 0100
r 3210
t 3210

Assembler Syntax

AE_LB a0..15(arr), a0..15(art)

C Syntax

#include <xtensa/tie/xt_hifi2.h>

extern unsigned AE_LB(unsigned ba);

Description

AE_LB is a look ahead in the bit stream. Returns as few as 0 bits or as many as 16 bits from the head of the bit stream. The number of bits to return is given by the low five bits of a0, and must lie in the range [0..16]. No state is updated; this is a lookahead instruction. The bits from the bit stream are returned right-justified in a.

Implementation Pipeline

In Out
AE_BITPTR Mstage, AE_BITHEAD Mstage, art Mstage arr Mstage

Protos that use AE_LB

proto AE_LB { out uint32 a, in uint32 ba }{}{
AE_LB a, ba;
}