kolibrios/programs/media/ac97 mp3/trunk/mp3dec/fdct.c

291 lines
7.5 KiB
C
Raw Normal View History

#include <math.h>
static float coef32[31]; /* 32 pt dct coefs */
void fdct_init() /* gen coef for N=32 (31 coefs) */
{
int p, n, i, k;
double t, pi;
pi = 4.0 * atan(1.0);
n = 16;
k = 0;
for (i = 0; i < 5; i++, n = n / 2) {
for (p = 0; p < n; p++, k++) {
t = (pi / (4 * n)) * (2 * p + 1);
coef32[k] = (float) (0.50 / cos(t));
}
}
}
static void forward_bf(int m, int n, float x[], float f[], float coef[])
{
int i, j, n2;
int p, q, p0, k;
p0 = 0;
n2 = n >> 1;
for (i = 0; i < m; i++, p0 += n) {
k = 0;
p = p0;
q = p + n - 1;
for (j = 0; j < n2; j++, p++, q--, k++) {
f[p] = x[p] + x[q];
f[n2 + p] = coef[k] * (x[p] - x[q]);
}
}
}
/*------------------------------------------------------------*/
static void back_bf(int m, int n, float x[], float f[])
{
int i, j, n2, n21;
int p, q, p0;
p0 = 0;
n2 = n >> 1;
n21 = n2 - 1;
for (i = 0; i < m; i++, p0 += n) {
p = p0;
q = p0;
for (j = 0; j < n2; j++, p += 2, q++)
f[p] = x[q];
p = p0 + 1;
for (j = 0; j < n21; j++, p += 2, q++)
f[p] = x[q] + x[q + 1];
f[p] = x[q];
}
}
/*------------------------------------------------------------*/
extern int m_enableEQ;
extern float m_equalizer[32];
void fdct32(float x[], float c[])
{
float a[32]; /* ping pong buffers */
float b[32];
int p, q;
if (m_enableEQ) {
for (p = 0; p < 32; p++) x[p] *= m_equalizer[p];
}
/* special first stage */
for (p = 0, q = 31; p < 16; p++, q--) {
a[p] = x[p] + x[q];
a[16 + p] = coef32[p] * (x[p] - x[q]);
}
forward_bf(2, 16, a, b, coef32 + 16);
forward_bf(4, 8, b, a, coef32 + 16 + 8);
forward_bf(8, 4, a, b, coef32 + 16 + 8 + 4);
forward_bf(16, 2, b, a, coef32 + 16 + 8 + 4 + 2);
back_bf(8, 4, a, b);
back_bf(4, 8, b, a);
back_bf(2, 16, a, b);
back_bf(1, 32, b, c);
}
/*------------------------------------------------------------*/
void fdct32_dual(float x[], float c[])
{
float a[32]; /* ping pong buffers */
float b[32];
int p, pp, qq;
if (m_enableEQ) {
for (p = 0; p < 32; p++) x[p] *= m_equalizer[p];
}
/* special first stage for dual chan (interleaved x) */
pp = 0;
qq = 2 * 31;
for (p = 0; p < 16; p++, pp += 2, qq -= 2)
{
a[p] = x[pp] + x[qq];
a[16 + p] = coef32[p] * (x[pp] - x[qq]);
}
forward_bf(2, 16, a, b, coef32 + 16);
forward_bf(4, 8, b, a, coef32 + 16 + 8);
forward_bf(8, 4, a, b, coef32 + 16 + 8 + 4);
forward_bf(16, 2, b, a, coef32 + 16 + 8 + 4 + 2);
back_bf(8, 4, a, b);
back_bf(4, 8, b, a);
back_bf(2, 16, a, b);
back_bf(1, 32, b, c);
}
/*---------------convert dual to mono------------------------------*/
void fdct32_dual_mono(float x[], float c[])
{
float a[32]; /* ping pong buffers */
float b[32];
float t1, t2;
int p, pp, qq;
/* special first stage */
pp = 0;
qq = 2 * 31;
for (p = 0; p < 16; p++, pp += 2, qq -= 2)
{
t1 = 0.5F * (x[pp] + x[pp + 1]);
t2 = 0.5F * (x[qq] + x[qq + 1]);
a[p] = t1 + t2;
a[16 + p] = coef32[p] * (t1 - t2);
}
forward_bf(2, 16, a, b, coef32 + 16);
forward_bf(4, 8, b, a, coef32 + 16 + 8);
forward_bf(8, 4, a, b, coef32 + 16 + 8 + 4);
forward_bf(16, 2, b, a, coef32 + 16 + 8 + 4 + 2);
back_bf(8, 4, a, b);
back_bf(4, 8, b, a);
back_bf(2, 16, a, b);
back_bf(1, 32, b, c);
}
/*------------------------------------------------------------*/
/*---------------- 16 pt fdct -------------------------------*/
void fdct16(float x[], float c[])
{
float a[16]; /* ping pong buffers */
float b[16];
int p, q;
/* special first stage (drop highest sb) */
a[0] = x[0];
a[8] = coef32[16] * x[0];
for (p = 1, q = 14; p < 8; p++, q--)
{
a[p] = x[p] + x[q];
a[8 + p] = coef32[16 + p] * (x[p] - x[q]);
}
forward_bf(2, 8, a, b, coef32 + 16 + 8);
forward_bf(4, 4, b, a, coef32 + 16 + 8 + 4);
forward_bf(8, 2, a, b, coef32 + 16 + 8 + 4 + 2);
back_bf(4, 4, b, a);
back_bf(2, 8, a, b);
back_bf(1, 16, b, c);
}
/*------------------------------------------------------------*/
/*---------------- 16 pt fdct dual chan---------------------*/
void fdct16_dual(float x[], float c[])
{
float a[16]; /* ping pong buffers */
float b[16];
int p, pp, qq;
/* special first stage for interleaved input */
a[0] = x[0];
a[8] = coef32[16] * x[0];
pp = 2;
qq = 2 * 14;
for (p = 1; p < 8; p++, pp += 2, qq -= 2)
{
a[p] = x[pp] + x[qq];
a[8 + p] = coef32[16 + p] * (x[pp] - x[qq]);
}
forward_bf(2, 8, a, b, coef32 + 16 + 8);
forward_bf(4, 4, b, a, coef32 + 16 + 8 + 4);
forward_bf(8, 2, a, b, coef32 + 16 + 8 + 4 + 2);
back_bf(4, 4, b, a);
back_bf(2, 8, a, b);
back_bf(1, 16, b, c);
}
/*------------------------------------------------------------*/
/*---------------- 16 pt fdct dual to mono-------------------*/
void fdct16_dual_mono(float x[], float c[])
{
float a[16]; /* ping pong buffers */
float b[16];
float t1, t2;
int p, pp, qq;
/* special first stage */
a[0] = 0.5F * (x[0] + x[1]);
a[8] = coef32[16] * a[0];
pp = 2;
qq = 2 * 14;
for (p = 1; p < 8; p++, pp += 2, qq -= 2)
{
t1 = 0.5F * (x[pp] + x[pp + 1]);
t2 = 0.5F * (x[qq] + x[qq + 1]);
a[p] = t1 + t2;
a[8 + p] = coef32[16 + p] * (t1 - t2);
}
forward_bf(2, 8, a, b, coef32 + 16 + 8);
forward_bf(4, 4, b, a, coef32 + 16 + 8 + 4);
forward_bf(8, 2, a, b, coef32 + 16 + 8 + 4 + 2);
back_bf(4, 4, b, a);
back_bf(2, 8, a, b);
back_bf(1, 16, b, c);
}
/*------------------------------------------------------------*/
/*---------------- 8 pt fdct -------------------------------*/
void fdct8(float x[], float c[])
{
float a[8]; /* ping pong buffers */
float b[8];
int p, q;
/* special first stage */
b[0] = x[0] + x[7];
b[4] = coef32[16 + 8] * (x[0] - x[7]);
for (p = 1, q = 6; p < 4; p++, q--)
{
b[p] = x[p] + x[q];
b[4 + p] = coef32[16 + 8 + p] * (x[p] - x[q]);
}
forward_bf(2, 4, b, a, coef32 + 16 + 8 + 4);
forward_bf(4, 2, a, b, coef32 + 16 + 8 + 4 + 2);
back_bf(2, 4, b, a);
back_bf(1, 8, a, c);
}
/*---------------- 8 pt fdct dual chan---------------------*/
void fdct8_dual(float x[], float c[])
{
float a[8]; /* ping pong buffers */
float b[8];
int p, pp, qq;
/* special first stage for interleaved input */
b[0] = x[0] + x[14];
b[4] = coef32[16 + 8] * (x[0] - x[14]);
pp = 2;
qq = 2 * 6;
for (p = 1; p < 4; p++, pp += 2, qq -= 2)
{
b[p] = x[pp] + x[qq];
b[4 + p] = coef32[16 + 8 + p] * (x[pp] - x[qq]);
}
forward_bf(2, 4, b, a, coef32 + 16 + 8 + 4);
forward_bf(4, 2, a, b, coef32 + 16 + 8 + 4 + 2);
back_bf(2, 4, b, a);
back_bf(1, 8, a, c);
}
/*---------------- 8 pt fdct dual to mono---------------------*/
void fdct8_dual_mono(float x[], float c[])
{
float a[8]; /* ping pong buffers */
float b[8];
float t1, t2;
int p, pp, qq;
/* special first stage */
t1 = 0.5F * (x[0] + x[1]);
t2 = 0.5F * (x[14] + x[15]);
b[0] = t1 + t2;
b[4] = coef32[16 + 8] * (t1 - t2);
pp = 2;
qq = 2 * 6;
for (p = 1; p < 4; p++, pp += 2, qq -= 2)
{
t1 = 0.5F * (x[pp] + x[pp + 1]);
t2 = 0.5F * (x[qq] + x[qq + 1]);
b[p] = t1 + t2;
b[4 + p] = coef32[16 + 8 + p] * (t1 - t2);
}
forward_bf(2, 4, b, a, coef32 + 16 + 8 + 4);
forward_bf(4, 2, a, b, coef32 + 16 + 8 + 4 + 2);
back_bf(2, 4, b, a);
back_bf(1, 8, a, c);
}