Texas Instruments TMS320C67X Reference Manual page 201

LMBD
Syntax
Compatibility
Opcode
31 29 28 27
creg z dst
3 1 5
Description
SPRU733
Leftmost Bit Detection
LMBD (.unit) src1, src2, dst
.unit = .L1 or .L2
C62x, C64x, C67x, and C67x+ CPU
23 22 18
src2
5
Opcode map field used...
src1
src2
dst
src1
src2
dst
The LSB of the src1 operand determines whether to search for a leftmost 1 or 0
in src2. The number of bits to the left of the first 1 or 0 when searching for a 1
or 0, respectively, is placed in dst.
The following diagram illustrates the operation of LMBD for several cases.
When searching for 0 in src2, LMBD returns 0:
0 1 x x x x x x x
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
When searching for 1 in src2, LMBD returns 4:
0 0 0 0 1 x x x x
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
When searching for 0 in src2, LMBD returns 32:
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
17 13 12 11
src1/cst5 x
5 1
For operand type...
uint
xuint
uint
cst5
xuint
uint
x x x x x x x x x x x x x x x x x x x x x x x
x x x x x x x x x x x x x x x
Leftmost Bit Detection
5 4 3
op 1 1 0 s p
7
Unit Opfield
.L1, .L2 110 1011
.L1, .L2 110 1010
8 7 6 5 4 3
x x x x x
8 7 6 5 4 3
1 1 1 1 1 1 1 1 1
8 7 6 5 4 3
Instruction Set
LMBD
2 1 0
1 1
2 1 0
x x x
2 1 0
2 1 0
3-141