User guide

70 www.xilinx.com System Generator for DSP User Guide
UG640 (v 12.2) July 23, 2010
Chapter 1: Hardware Design Using System Generator
OP_DROP = 6;
q = acc;
active = acc_active;
if rst
acc = 0;
acc_active = false;
stack_pt = 0;
elseif en
if ~is_oper
% enter data, push
if acc_active
stack_pt = xfix(stack_pt_prec, stack_pt + 1);
mem(stack_pt) = acc;
stack_active = true;
else
acc_active = true;
end
acc = din;
else
if op == OP_NEG
% unary op, no stack op
acc = -acc;
elseif stack_active
b = mem(stack_pt);
switch double(op)
case OP_ADD
acc = acc + b;
case OP_SUB
acc = b - acc ;
case OP_MULT
acc = acc * b;
case OP_DROP
acc = b;
end
stack_pt = stack_pt - 1;
elseif acc_active
acc_active = false;
acc = 0;
end
end
end
stack_active = stack_pt ~= 0;