MAX2VIT

 

 

 

 

MAX2VIT

MAX2

MAX2VIT

 

for Viterbi Kernel (DALU)

Operation

 

Assembler Syntax

If Da.L > Db.L, then 0 → VFn, Da.L → Db.L

 

MAX2VIT Da,Db

 

else 1 → VFn

 

 

Da

Db

VFn

 

 

 

 

 

 

D4.L

D2.L

VF0

 

 

 

D4.H

D2.H

VF1

 

 

 

D0.L

D6.L

VF2

 

 

 

D0.H

D6.H

VF3

 

 

 

D12.L

D10.L

VF0

 

 

 

D12.H

D10.H

VF1

 

 

 

D8.L

D14.L

VF2

 

 

 

D8.H

D14.H

VF3

 

 

 

Description

These operations independently compare the 16-bit contents of the HP and LP of a data register pair to find the larger value. They copy the larger value to the corresponding portion in the second data register and set or clear Viterbi flags (VF0–VF3 in SR) to indicate which portions are larger. The HP and LP of the two registers are compared separately as 16-bit signed values and the Viterbi flags are set or cleared accordingly. These instructions are similar to MAX2, except they also set Viterbi flags. The MAX2VIT instructions are intended to optimize implementation of the Viterbi decoder algorithm. The MAX2VIT instruction is used with conjunction with the VSL instruction (see page A-423).

MAX2VIT Da,Db

For the low portion comparison, the instruction clears VFn (n=0, 2) if the LP of Da is greater than the LP of Db. It then copies the contents of the LP of Da to the LP of Db. It sets VFn (n=0, 2) if the LP of Da is not greater than the LP of Db. For the high portion comparison, this instruction clears VFn (n=1, 3) if the HP of Da is greater than the HP of Db. It then copies the contents of the HP of Da to the HP of Db. It sets VFn (n=1, 3) if the HP of Da is not greater than the HP of Db. The high bank of registers can also be used: D12 and D8 substituted for Da, and D10 and D14 substituted for Db. The encoding for the substitution is done with a prefix.

Status and Conditions that Affect Instruction

None.

SC140 DSP Core Reference Manual

A-249

Page 563
Image 563
Freescale Semiconductor SC140 specifications If Da.L Db.L, then 0 → VFn, Da.L → Db.L, Else 1 → VFn, MAX2VIT Da,Db