| 0,0 → 1,222 |
|---|
| #include <math.h> |
| |
| /*------ 18 point xform -------*/ |
| static float w[18]; |
| static float w2[9]; |
| static float coef[9][4]; |
| |
| static float v[6]; |
| static float v2[3]; |
| static float coef87; |
| /* |
| typedef struct |
| { |
| float *w; |
| float *w2; |
| void *coef; |
| } |
| IMDCT_INIT_BLOCK; |
| |
| static IMDCT_INIT_BLOCK imdct_info_18 = |
| {w, w2, coef}; |
| static IMDCT_INIT_BLOCK imdct_info_6 = |
| {v, v2, &coef87}; |
| */ |
| /*=============================================================*/ |
| void imdct_init() |
| { |
| int k, p, n; |
| double t, pi; |
| // IMDCT_INIT_BLOCK *addr; |
| // float *w, *w2; |
| // float *v, *v2, *coef87; |
| |
| /*--- 18 point --*/ |
| // addr = imdct_init_addr_18(); |
| // w = addr->w; |
| // w2 = addr->w2; |
| // coef = addr->coef; |
| /*----*/ |
| n = 18; |
| pi = 4.0 * atan(1.0); |
| t = pi / (4 * n); |
| for (p = 0; p < n; p++) |
| w[p] = (float) (2.0 * cos(t * (2 * p + 1))); |
| for (p = 0; p < 9; p++) |
| w2[p] = (float) (2.0 *cos(2 * t * (2 * p + 1))); |
| |
| t = pi / (2 * n); |
| for (k = 0; k < 9; k++) |
| { |
| for (p = 0; p < 4; p++) |
| coef[k][p] = (float) (cos(t * (2 * k) * (2 * p + 1))); |
| } |
| |
| /*--- 6 point */ |
| // addr = imdct_init_addr_6(); |
| // v = addr->w; |
| // v2 = addr->w2; |
| // coef87 = addr->coef; |
| /*----*/ |
| n = 6; |
| pi = 4.0 * atan(1.0); |
| t = pi / (4 * n); |
| for (p = 0; p < n; p++) |
| v[p] = (float) (2.0 *cos(t * (2 * p + 1))); |
| |
| for (p = 0; p < 3; p++) |
| v2[p] = (float) (2.0 *cos(2 * t * (2 * p + 1))); |
| |
| t = pi / (2 * n); |
| k = 1; |
| p = 0; |
| coef87 = (float) (cos(t * (2 * k) * (2 * p + 1))); |
| /* adjust scaling to save a few mults */ |
| for (p = 0; p < 6; p++) |
| v[p] = v[p] / 2.0f; |
| coef87 = (float) (2.0 * coef87); |
| } |
| /*--------------------------------------------------------------------*/ |
| void imdct18(float f[18]) /* 18 point */ |
| { |
| int p; |
| float a[9], b[9]; |
| float ap, bp, a8p, b8p; |
| float g1, g2; |
| |
| |
| for (p = 0; p < 4; p++) |
| { |
| g1 = w[p] * f[p]; |
| g2 = w[17 - p] * f[17 - p]; |
| ap = g1 + g2; // a[p] |
| |
| bp = w2[p] * (g1 - g2); // b[p] |
| |
| g1 = w[8 - p] * f[8 - p]; |
| g2 = w[9 + p] * f[9 + p]; |
| a8p = g1 + g2; // a[8-p] |
| |
| b8p = w2[8 - p] * (g1 - g2); // b[8-p] |
| |
| a[p] = ap + a8p; |
| a[5 + p] = ap - a8p; |
| b[p] = bp + b8p; |
| b[5 + p] = bp - b8p; |
| } |
| g1 = w[p] * f[p]; |
| g2 = w[17 - p] * f[17 - p]; |
| a[p] = g1 + g2; |
| b[p] = w2[p] * (g1 - g2); |
| |
| |
| f[0] = 0.5f * (a[0] + a[1] + a[2] + a[3] + a[4]); |
| f[1] = 0.5f * (b[0] + b[1] + b[2] + b[3] + b[4]); |
| |
| f[2] = coef[1][0] * a[5] + coef[1][1] * a[6] + coef[1][2] * a[7] |
| + coef[1][3] * a[8]; |
| f[3] = coef[1][0] * b[5] + coef[1][1] * b[6] + coef[1][2] * b[7] |
| + coef[1][3] * b[8] - f[1]; |
| f[1] = f[1] - f[0]; |
| f[2] = f[2] - f[1]; |
| |
| f[4] = coef[2][0] * a[0] + coef[2][1] * a[1] + coef[2][2] * a[2] |
| + coef[2][3] * a[3] - a[4]; |
| f[5] = coef[2][0] * b[0] + coef[2][1] * b[1] + coef[2][2] * b[2] |
| + coef[2][3] * b[3] - b[4] - f[3]; |
| f[3] = f[3] - f[2]; |
| f[4] = f[4] - f[3]; |
| |
| f[6] = coef[3][0] * (a[5] - a[7] - a[8]); |
| f[7] = coef[3][0] * (b[5] - b[7] - b[8]) - f[5]; |
| f[5] = f[5] - f[4]; |
| f[6] = f[6] - f[5]; |
| |
| f[8] = coef[4][0] * a[0] + coef[4][1] * a[1] + coef[4][2] * a[2] |
| + coef[4][3] * a[3] + a[4]; |
| f[9] = coef[4][0] * b[0] + coef[4][1] * b[1] + coef[4][2] * b[2] |
| + coef[4][3] * b[3] + b[4] - f[7]; |
| f[7] = f[7] - f[6]; |
| f[8] = f[8] - f[7]; |
| |
| f[10] = coef[5][0] * a[5] + coef[5][1] * a[6] + coef[5][2] * a[7] |
| + coef[5][3] * a[8]; |
| f[11] = coef[5][0] * b[5] + coef[5][1] * b[6] + coef[5][2] * b[7] |
| + coef[5][3] * b[8] - f[9]; |
| f[9] = f[9] - f[8]; |
| f[10] = f[10] - f[9]; |
| |
| f[12] = 0.5f * (a[0] + a[2] + a[3]) - a[1] - a[4]; |
| f[13] = 0.5f * (b[0] + b[2] + b[3]) - b[1] - b[4] - f[11]; |
| f[11] = f[11] - f[10]; |
| f[12] = f[12] - f[11]; |
| |
| f[14] = coef[7][0] * a[5] + coef[7][1] * a[6] + coef[7][2] * a[7] |
| + coef[7][3] * a[8]; |
| f[15] = coef[7][0] * b[5] + coef[7][1] * b[6] + coef[7][2] * b[7] |
| + coef[7][3] * b[8] - f[13]; |
| f[13] = f[13] - f[12]; |
| f[14] = f[14] - f[13]; |
| |
| f[16] = coef[8][0] * a[0] + coef[8][1] * a[1] + coef[8][2] * a[2] |
| + coef[8][3] * a[3] + a[4]; |
| f[17] = coef[8][0] * b[0] + coef[8][1] * b[1] + coef[8][2] * b[2] |
| + coef[8][3] * b[3] + b[4] - f[15]; |
| f[15] = f[15] - f[14]; |
| f[16] = f[16] - f[15]; |
| f[17] = f[17] - f[16]; |
| } |
| /*--------------------------------------------------------------------*/ |
| /* does 3, 6 pt dct. changes order from f[i][window] c[window][i] */ |
| void imdct6_3(float f[]) /* 6 point */ |
| { |
| int w; |
| float buf[18]; |
| float *a, *c; // b[i] = a[3+i] |
| |
| float g1, g2; |
| float a02, b02; |
| |
| c = f; |
| a = buf; |
| for (w = 0; w < 3; w++) |
| { |
| g1 = v[0] * f[3 * 0]; |
| g2 = v[5] * f[3 * 5]; |
| a[0] = g1 + g2; |
| a[3 + 0] = v2[0] * (g1 - g2); |
| |
| g1 = v[1] * f[3 * 1]; |
| g2 = v[4] * f[3 * 4]; |
| a[1] = g1 + g2; |
| a[3 + 1] = v2[1] * (g1 - g2); |
| |
| g1 = v[2] * f[3 * 2]; |
| g2 = v[3] * f[3 * 3]; |
| a[2] = g1 + g2; |
| a[3 + 2] = v2[2] * (g1 - g2); |
| |
| a += 6; |
| f++; |
| } |
| |
| a = buf; |
| for (w = 0; w < 3; w++) |
| { |
| a02 = (a[0] + a[2]); |
| b02 = (a[3 + 0] + a[3 + 2]); |
| c[0] = a02 + a[1]; |
| c[1] = b02 + a[3 + 1]; |
| c[2] = coef87 * (a[0] - a[2]); |
| c[3] = coef87 * (a[3 + 0] - a[3 + 2]) - c[1]; |
| c[1] = c[1] - c[0]; |
| c[2] = c[2] - c[1]; |
| c[4] = a02 - a[1] - a[1]; |
| c[5] = b02 - a[3 + 1] - a[3 + 1] - c[3]; |
| c[3] = c[3] - c[2]; |
| c[4] = c[4] - c[3]; |
| c[5] = c[5] - c[4]; |
| a += 6; |
| c += 6; |
| } |
| } |