-static int zigzagtable[64] = {
- 0, 1, 5, 6, 14, 15, 27, 28,
- 2, 4, 7, 13, 16, 26, 29, 42,
- 3, 8, 12, 17, 25, 30, 41, 43,
- 9, 11, 18, 24, 31, 40, 44, 53,
- 10, 19, 23, 32, 39, 45, 52, 54,
- 20, 22, 33, 38, 46, 51, 55, 60,
- 21, 34, 37, 47, 50, 56, 59, 61,
- 35, 36, 48, 49, 57, 58, 62, 63};
-
-static void zigzag(int*src)
-{
- int tmp[64];
- int t;
- for(t=0;t<64;t++) {
- tmp[zigzagtable[t]] = src[t];
- }
- memcpy(src, tmp, sizeof(int)*64);
-}
-
-#define PI 3.14159265358979
-#define SQRT2 1.414214
-#define RSQRT2 (1.0/1.414214)
-
-static double table[8][8] =
-{
-{0.707106781186548,0.707106781186548,0.707106781186548,0.707106781186548,0.707106781186548,0.707106781186548,0.707106781186548,0.707106781186548},
-{0.980785280403230,0.831469612302545,0.555570233019602,0.195090322016128,-0.195090322016128,-0.555570233019602,-0.831469612302545,-0.980785280403230},
-{0.923879532511287,0.382683432365090,-0.382683432365090,-0.923879532511287,-0.923879532511287,-0.382683432365090,0.382683432365090,0.923879532511287},
-{0.831469612302545,-0.195090322016128,-0.980785280403230,-0.555570233019602,0.555570233019602,0.980785280403230,0.195090322016129,-0.831469612302545},
-{0.707106781186548,-0.707106781186547,-0.707106781186548,0.707106781186547,0.707106781186548,-0.707106781186547,-0.707106781186547,0.707106781186547},
-{0.555570233019602,-0.980785280403230,0.195090322016128,0.831469612302545,-0.831469612302545,-0.195090322016128,0.980785280403231,-0.555570233019602},
-{0.382683432365090,-0.923879532511287,0.923879532511287,-0.382683432365090,-0.382683432365091,0.923879532511287,-0.923879532511286,0.382683432365090},
-{0.195090322016128,-0.555570233019602,0.831469612302545,-0.980785280403231,0.980785280403230,-0.831469612302545,0.555570233019602,-0.195090322016129}
-};
-
-static void dct(int*src)
-{
- double tmp[64];
- int x,y,u,v,t;
-
- for(v=0;v<8;v++)
- for(u=0;u<8;u++)
- {
- double c = 0;
- for(x=0;x<8;x++)
- {
- c+=table[u][x]*src[v*8+x];
- }
- tmp[v*8+u] = c;
- }
- for(u=0;u<8;u++)
- for(v=0;v<8;v++)
- {
- double c = 0;
- for(y=0;y<8;y++)
- {
- c+=table[v][y]*tmp[y*8+u];
- }
- src[v*8+u] = (int)(c*0.25+0.5);
- }
-}
-
-static void idct(int*src)
-{
- double tmp[64];
- int x,y,u,v;
- for(y=0;y<8;y++)
- for(x=0;x<8;x++)
- {
- double c = 0;
- for(u=0;u<8;u++)
- {
- c+=table[u][x]*src[y*8+u];
- }
- tmp[y*8+x] = c;
- }
- for(y=0;y<8;y++)
- for(x=0;x<8;x++)
- {
- double c = 0;
- for(v=0;v<8;v++)
- {
- c+=table[v][y]*tmp[v*8+x];
- }
- src[y*8+x] = (int)(c*0.25+0.5);
- }
-}
-
-static double c[8] = {1.0,
-0.980785280403230, // cos(Pi*1/16), sin(Pi*7/16)
-0.923879532511287, // cos(Pi*2/16), sin(Pi*6/16)
-0.831469612302545, // cos(Pi*3/16), sin(Pi*5/16)
-0.707106781186548, // cos(Pi*4/16), sin(Pi*4/16), 1/sqrt(2)
-0.555570233019602, // cos(Pi*5/16), sin(Pi*3/16)
-0.382683432365090, // cos(Pi*6/16), sin(Pi*2/16)
-0.195090322016128 // cos(Pi*7/16), sin(Pi*1/16)
-};
-
-static double cc[8];
-int ccquant = -1;
-
-static void preparequant(int quant)
-{
- if(ccquant == quant)
- return;
- cc[0] = c[0]/(quant*2*4);
- cc[1] = c[1]/(quant*2*4);
- cc[2] = c[2]/(quant*2*4);
- cc[3] = c[3]/(quant*2*4);
- cc[4] = c[4]/(quant*2*4);
- cc[5] = c[5]/(quant*2*4);
- cc[6] = c[6]/(quant*2*4);
- cc[7] = c[7]/(quant*2*4);
- ccquant = quant;
-}
-
-inline static void innerdct(double*a,double*b, double*c)
-{
- // c1*c7*2 = c6
- // c2*c6*2 = c4
- // c3*c5*2 = c2
- // c4*c4*2 = 1
-
- //{ 1, 3, 5, 7, -7, -5, -3, -1},
- //{ 3, -7, -1, -5, 5, 1, 7, -3},
- //{ 5, -1, 7, 3, -3, -7, 1, -5},
- //{ 7, -5, 3, -1, 1, -3, 5, -7}
- double b0,b1,b2,b3,b4,b5;
- b2 = (a[0]+a[7]);
- b3 = (a[1]+a[6]);
- b4 = (a[2]+a[5]);
- b5 = (a[3]+a[4]);
-
- b0 = (b2+b5)*c[4];
- b1 = (b3+b4)*c[4];
- b[0*8] = b0 + b1;
- b[4*8] = b0 - b1;
- b[2*8] = (b2-b5)*c[2] + (b3-b4)*c[6];
- b[6*8] = (b2-b5)*c[6] + (b4-b3)*c[2];
-
- b0 = (a[0]-a[7]);
- b1 = (a[1]-a[6]);
- b2 = (a[2]-a[5]);
- b3 = (a[3]-a[4]);
-
- b[1*8] = b0*c[1] + b1*c[3] + b2*c[5] + b3*c[7];
- b[3*8] = b0*c[3] - b1*c[7] - b2*c[1] - b3*c[5];
- b[5*8] = b0*c[5] - b1*c[1] + b2*c[7] + b3*c[3];
- b[7*8] = b0*c[7] - b1*c[5] + b2*c[3] - b3*c[1];
-}
-
-static void dct2(int*src, int*dest)
-{
- double tmp[64], tmp2[64];
- double*p;
- int u,x,v,t;
-
- for(t=0;t<64;t++)
- tmp2[t] = src[t];
-
- for(v=0;v<8;v++)
- {
- double* a=&tmp2[v*8];
- double* b=&tmp[v];
- innerdct(a,b,c);
- }
- for(v=0;v<8;v++)
- {
- double* a=&tmp[v*8];
- double* b=&tmp2[v];
- innerdct(a,b,cc);
- }
- for(t=0;t<64;t++) {
- int v = (int)(tmp2[t]);
- if(v>127) v=127;
- if(v<-127) v=-127;
- dest[zigzagtable[t]] = v;
- }
-}
-
-