c语言示例aan算法

#define C2   30274       // 2 COS (PI/8) 1.84776
#define C4   23171       // SQRT(2)  1.41421
#define C6   12540       // 2 SIN (PI/8)  0.76537
#define C6pC2   42814    file://C6+C2   2.61313
#define C6sC2   (-17734) //        -1.08239
#define RC0    14
#define RC1    18
#define ROUND   (1<<(RC1-1))

//  do 80 times of multiply; fastidct :176;

#define idct_unit(a,b) {x4 = x5 - x3;        \
               t1 = x5 + x3;        \
                     x3 = (x2+x6)<                     x2 = (x2-x6)*C4-x3;  \
                     t0 = x1 + x7;        \
                        x6=  x1 - x7;        \
                        x7=  (t0 + t1)<                     x5 = (t0 - t1)*C4;   \
                   t0=C6*(x4+x6);       \
                      x4=C6sC2*x4-t0;      \
                       x6=C6pC2*x6-t0;      \

t0=x6-x7;            \
                    x1=(a-b)<                   t1=t0-x5;            \
                  x6=(a+b)<                  x0=x4-t1;            \
                    x4=x3+x6;            \
                     x6-=x3;              \
                     x3=x1+x2;            \
                    x5=x1-x2;            }

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