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history of the filter. After performing the filtering operation, the delay contains<br />

a set of<br />

the most recently filtered data samples, and of the most recent output samples.<br />

(Note<br />

that to ensure correct operation of a particular filter implementation, it is<br />

advisable to<br />

initialize the delay values to zero by calling the corresponding initialization<br />

function.)<br />

In the filter implementations provided with the DSP Library the input data<br />

sequence is<br />

referred to as the sequence of source samples, while the resulting filtered<br />

sequence is<br />

called the destination samples. The filter coefficients (a,b) and delay are usually<br />

thought of as making up a filter structure. In all filter implementations, the input<br />

and<br />

và bộ hệ số có thể tạo ra kết quả bất ngờ.<br />

d) Đó là khuyến cáo rằng tình trạng đăng ký (SR) được kiểm tra sau khi hoàn<br />

thành<br />

mỗi lần gọi hàm. Đặc biệt, người dùng có thể kiểm tra việc SA, SB và SAB cờ<br />

sau<br />

hàm trả về để xác định độ bão hòa xảy ra.<br />

e) Các hoạt động đó trả về một vector đích có thể được lồng vào nhau, do đó, v<br />

dụ<br />

nếu:<br />

a = OP1 (b, c), với b = OP2 (d) và c = op3 (e, f), sau đó<br />

a = OP1 (OP2 (d), op3 (e, f))<br />

dsPIC<br />

®<br />

Thư viện Công cụ Ngôn ngữ<br />

output data samples may be allocated in default RAM memory space (X-Data or<br />

DS51456B trang 40<br />

2004 Microchip Technology Inc<br />

Y-Data). Filter coefficients may reside either in X-Data memory or program<br />

memory,<br />

and filter delay values must be accessed onlyfrom Y-Data.<br />

2.6.2 FIR and IIR Filter Implementations<br />

The properties of a filter depend on the value distribution of its coefficients. In<br />

particular,<br />

two types of filters are of special interest: Finite Impulse Response (FIR) filters,<br />

for<br />

which a[m] = 0 when 1 ≤m

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