CORDIC算法的matlab实现

大笨象

5 D, Y- j! k5 F
不知道有木有人研究这个，比较偏向于硬件描述。
! q# w% m! A6 }& K6 T% G5 J2 G今天先发一个sine cose函数的实现。
6 e$ f. ]# M3 `, a/ s7 U4 ~有兴趣的可以看一下，m文件见附件。
function v=f_cordic(beta,n)
' K2 W% \4 `' F( g  h1 e/ r; R6 Fif beta < -pi/2 || beta > pi/2
/ _0 A3 a- g* W% `    if beta < 0
        v=f_cordic(beta + pi,n);
    else
        v=f_cordic(beta - pi,n);
; e: E4 R! v5 a    end
    v = -v;% flip the sign for second or third quadrant
    return
end
/ a# J' N& r  p" b9 @7 E: [% Initialization of tables of constants used by CORDIC
5 D- p% }/ q: x% |/ w) x: j1 ^7 p4 C9 ]% need a table of arctangents of negative powers of two, in radians:
) l, t& w# x2 w' n- S% angles = atan(2.^-(0:27));
angles =  [  ...
    0.78539816339745   0.46364760900081   0.24497866312686   0.12435499454676 ...
    0.06241880999596   0.03123983343027   0.01562372862048   0.00781234106010 ...
! S4 s6 _$ Q6 Z6 h7 C3 @    0.00390623013197   0.00195312251648   0.00097656218956   0.00048828121119 ...
& V  H& ?) _5 Z9 V    0.00024414062015   0.00012207031189   0.00006103515617   0.00003051757812 ...
    0.00001525878906   0.00000762939453   0.00000381469727   0.00000190734863 ...
1 L  x' q* V% q' C4 N  D( J0 O    0.00000095367432   0.00000047683716   0.00000023841858   0.00000011920929 ...
7 D) V; D% u" q5 [# x    0.00000005960464   0.00000002980232   0.00000001490116   0.00000000745058 ];
% and a table of products of reciprocal lengths of vectors [1, 2^-j]:
Kvalues = [ ...
% g0 R# M# C) i: _) K. ~    0.70710678118655   0.63245553203368   0.61357199107790   0.60883391251775 ...
    0.60764825625617   0.60735177014130   0.60727764409353   0.60725911229889 ...
    0.60725447933256   0.60725332108988   0.60725303152913   0.60725295913894 ...
8 w0 I; S& e* Z7 a3 [    0.60725294104140   0.60725293651701   0.60725293538591   0.60725293510314 ...
    0.60725293503245   0.60725293501477   0.60725293501035   0.60725293500925 ...
    0.60725293500897   0.60725293500890   0.60725293500889   0.60725293500888 ];
Kn = Kvalues(min(n, length(Kvalues)));

% Initialize loop variables:
& `  V3 M- z6 }& O2 iv = [1;0]; % start with 2-vector cosine and sine of zero
poweroftwo = 1;
' |1 L5 m- s9 ~" Y8 e% Iterations
for j = 1:n;
    if beta < 0
+ ~9 k* R, V1 M0 {" w        sigma = -1;
- A/ M- q" v) ^. M    else
        sigma = 1;
8 C$ T+ ]# x& q" w" g9 p" ]    end
; K' ?2 {0 D6 y7 G  ]( {    % update the angle from table, or eventually by just dividing by two
    if j <= length(angles)
' E; ~1 Q$ V6 J+ |- b' K        angle = angles(j);
+ I+ f1 w3 Q7 h+ C: z$ t    else
) j" ]1 E2 l& M        angle = angle/2;
8 z" L/ d! S! Y; O/ T1 M4 J    end
3 u1 O9 W; f3 v) z    factor = sigma * poweroftwo;
    R = [1, -factor; factor, 1];
    v = R * v; % 2-by-2 mtrix multiply
    beta = beta - sigma * angle; % update the remaining angle
    poweroftwo = poweroftwo / 2;
end
% Adjust length of output vector to be [cos(beta), sin(beta)]:
v = v * Kn;
# [& I' Q  p8 L5 xreturn

使用20位寄存器，仿真波形如下：

' `) }1 O2 R/ j1 w

杨帆

我表示学习了

zhangjichang

这是什么算法？第一次听说

赛才

我表示很给力

大笨象

zhangjichang 发表于 2011-6-8 22:31
6 }' W7 s* p# J5 p7 w这是什么算法？第一次听说

2 K& O3 s, O% i这个，就是那个。感兴趣的话你还是自己搜搜吧。

大笨象

赛才 发表于 2011-6-9 15:01
我表示很给力

给力就好。呵呵

魅影骑士

顶一下！

yingzhen

费解。。。。。。。。。。。。。。。。

羅雲琦

有什麽用？求解

jt202010