AN2072 Freescale Semiconductor / Motorola, AN2072 Datasheet - Page 11

• Manufacturer Part Number: AN2072
• Description: AN2072, Decision Feedback Equalizer for StarCore-Based DSPs
• Manufacturer: Freescale Semiconductor / Motorola

The address register pointing to the memory that contains the complex-impulse response, h
This causes the pointer to wrap around before filling each column of the convolution matrix transpose when it
reaches the last entry of the channel-impulse response in the array, “channel_h”. Expressions used in the assembly
code shown in Code Listing 1 are defined as:
3.3.2 Matrix Multiply Block
The matrix multiply block efficiently generates the matrix product H
a matrix M, if read row-wise, the result is M and if read column-wise, the result is M
performed in this application is H
Freescale Semiconductor
1.
2.
3.
r0: #channel_h (Modulo 2)
r1: #conv_matrix
r2: holds the start location for each column in the #conv_matrix
add_col
loopstart1
transpose H
Code Listing 3. Assembly Code Used to Fill the Convolution Matrix
move.2f (r0)+,d0:d1
loopend1
moves.2f d0:d1,(r1)+n1
adda n2,r2
loopstart0
doensh1 #CHANNEL_MEM
move.2f (r0)+,d0:d1
tfra r2,r1; r1->r2=next
loopend0
Decision Feedback Equalizer for StarCore™-Based DSPs, Rev. 1
( )
=
*
× H. Recall that H
h
h
h
h
h
0 h
0 0 h
0 0 0 h
0 0 0 0 h
0 0 0 0 0 h
0 0 0 0 0 0 h
0 0 0 0 0 0 0 h
0
1
2
3
4
h
h
h
h
0 0 0 0 0 0 0
0
1
2
3
4
h
h
h
h
0 0 0 0 0 0
0
1
2
3
4
h
h
h
h
0 0 0 0 0
0
1
2
3
4
h
h
h
h
0 0 0 0
0
1
2
3
4
moves.2f d0:d1,(r1)+n1; d0=Re[channel_h(1)]
h
h
h
h
0 0 0
0
1
2
3
4
h
h
h
h
0 0
0
1
2
3
4
T
h
h
h
h
0
was generated instead of H, primarily to assist in this
0
1
2
3
4
Note: h
numbers, that is;
h
0…
0
*
= Re(h
× H. To simplify this implementation, given
h
4
; loop1 repeat
; #CHANNEL_MEM times
; d0=Re[channel_h(1)]
; and
; d1=Im[channel_h(1)]
; d1=Im[channel_h(1]]
; move d0 and d1 (r1)
; r1->r1+4*n1
; r2->r2+$24
; diagonal element
are each complex
0
) and Im(h
Implementation of the Algorithm
T
0
. The operation to be
)
0
…h
4
, is set as modulo.
Equation 23
11