MATLAB DESIGN HDL CODER RELEASE NOTES Betriebsanweisung PDF herunterladen (Seite 66)

66 www.xilinx.com System Generator for DSP User Guide

UG640 (v 12.2) July 23, 2010

Chapter 1: Hardware Design Using System Generator

The example contains two additional accumulator subsystems with MCode blocks using

the same M-function, but different parameter settings to accomplish different accumulator

implementations.

FIR Example and System Verification

This example shows how to use the MCode block to model FIRs. It also shows how to do

system verification with the MCode block.

The model contains two FIR blocks. Both are modeled with the MCode block and both are

synthesizable. The following are the two functions that model those two blocks.

function y = simple_fir(x, lat, coefs, len, c_nbits, c_binpt, o_nbits,

o_binpt)

coef_prec = {xlSigned, c_nbits, c_binpt, xlRound, xlWrap};

out_prec = {xlSigned, o_nbits, o_binpt};

coefs_xfix = xfix(coef_prec, coefs);

persistent coef_vec, coef_vec = xl_state(coefs_xfix, coef_prec);

persistent x_line, x_line = xl_state(zeros(1, len-1), x);

persistent p, p = xl_state(zeros(1, lat), out_prec, lat);

sum = x * coef_vec(0);

for idx = 1:len-1

sum = sum + x_line(idx-1) * coef_vec(idx);

sum = xfix(out_prec, sum);

end

y = p.back;

p.push_front_pop_back(sum);

x_line.push_front_pop_back(x);

function y = fir_transpose(x, lat, coefs, len, c_nbits, c_binpt,

o_nbits, o_binpt)

coef_prec = {xlSigned, c_nbits, c_binpt, xlRound, xlWrap};

out_prec = {xlSigned, o_nbits, o_binpt};

coefs_xfix = xfix(coef_prec, coefs);

persistent coef_vec, coef_vec = xl_state(coefs_xfix, coef_prec);

persistent reg_line, reg_line = xl_state(zeros(1, len), out_prec);

if lat <= 0

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MATLAB DESIGN HDL CODER RELEASE NOTES Betriebsanweisung Seite 66