csbt.c

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/*____________________________________________________________________________
	
	MP3 Decoding Libraries
	Lanuguages used: C, C++, ASM

	As much as I would love to, I cannot take
	full credit for writing this code.
	Xing Technology	made MPEG-Layer 3 for us
	to decode. =)
	- ULTiMaTuM -

	MPEG-Layer 3 (MP3)
	Copyright (C) 1995-1997 Xing Technology

  	NOTE: I only edited the bare-minimum. 90%
		of this is original decoding code...
		Hmm... that sounds strange =)

____________________________________________________________________________*/

/****  csbt.c  ***************************************************

MPEG audio decoder
dct and window format

Original revision made on 1/7/96 mod for Layer III
(The MP3 we know of today)
  
******************************************************************/

#include <stdlib.h>
#include <stdio.h>
#include <float.h>
#include <math.h>

void fdct32(float *, float *);
void fdct32_dual(float *, float *);
void fdct32_dual_mono(float *, float *);
void fdct16(float *, float *);
void fdct16_dual(float *, float *);
void fdct16_dual_mono(float *, float *);
void fdct8(float *, float *);
void fdct8_dual(float *, float *);
void fdct8_dual_mono(float *, float *);

void window(float *vbuf, int vb_ptr, short *pcm);
void window_dual(float *vbuf, int vb_ptr, short *pcm);
void window16(float *vbuf, int vb_ptr, short *pcm);
void window16_dual(float *vbuf, int vb_ptr, short *pcm);
void window8(float *vbuf, int vb_ptr, short *pcm);
void window8_dual(float *vbuf, int vb_ptr, short *pcm);
float *dct_coef_addr();

float *dct_coef_addr();

/*-------------------------------------------------------------------------*/
/* circular window buffers */
static signed int vb_ptr;
static signed int vb2_ptr;
static float vbuf[512];
static float vbuf2[512];

float *dct_coef_addr();

/*======================================================================*/
static void gencoef()		/* gen coef for N=32 (31 coefs) */
{
   int p, n, i, k;
   double t, pi;
   float *coef32;

   coef32 = dct_coef_addr();

   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));
      }
   }
}
/*------------------------------------------------------------*/
void sbt_init()
{
   int i;
   static int first_pass = 1;

   if (first_pass)
   {
      gencoef();
      first_pass = 0;
   }

/* clear window vbuf */
   for (i = 0; i < 512; i++)
   {
      vbuf[i] = 0.0F;
      vbuf2[i] = 0.0F;
   }
   vb2_ptr = vb_ptr = 0;

}
/*============================================================*/
/*============================================================*/
/*============================================================*/
void sbt_mono(float *sample, short *pcm, int n)
{
   int i;

   for (i = 0; i < n; i++)
   {
      fdct32(sample, vbuf + vb_ptr);
      window(vbuf, vb_ptr, pcm);
      sample += 64;
      vb_ptr = (vb_ptr - 32) & 511;
      pcm += 32;
   }

}
/*------------------------------------------------------------*/
void sbt_dual(float *sample, short *pcm, int n)
{
   int i;

   for (i = 0; i < n; i++)
   {
      fdct32_dual(sample, vbuf + vb_ptr);
      fdct32_dual(sample + 1, vbuf2 + vb_ptr);
      window_dual(vbuf, vb_ptr, pcm);
      window_dual(vbuf2, vb_ptr, pcm + 1);
      sample += 64;
      vb_ptr = (vb_ptr - 32) & 511;
      pcm += 64;
   }


}
/*------------------------------------------------------------*/
/* convert dual to mono */
void sbt_dual_mono(float *sample, short *pcm, int n)
{
   int i;

   for (i = 0; i < n; i++)
   {
      fdct32_dual_mono(sample, vbuf + vb_ptr);
      window(vbuf, vb_ptr, pcm);
      sample += 64;
      vb_ptr = (vb_ptr - 32) & 511;
      pcm += 32;
   }

}
/*------------------------------------------------------------*/
/* convert dual to left */
void sbt_dual_left(float *sample, short *pcm, int n)
{
   int i;

   for (i = 0; i < n; i++)
   {
      fdct32_dual(sample, vbuf + vb_ptr);
      window(vbuf, vb_ptr, pcm);
      sample += 64;
      vb_ptr = (vb_ptr - 32) & 511;
      pcm += 32;
   }
}
/*------------------------------------------------------------*/
/* convert dual to right */
void sbt_dual_right(float *sample, short *pcm, int n)
{
   int i;

   sample++;			/* point to right chan */
   for (i = 0; i < n; i++)
   {
      fdct32_dual(sample, vbuf + vb_ptr);
      window(vbuf, vb_ptr, pcm);
      sample += 64;
      vb_ptr = (vb_ptr - 32) & 511;
      pcm += 32;
   }
}
/*------------------------------------------------------------*/
/*---------------- 16 pt sbt's  -------------------------------*/
/*------------------------------------------------------------*/
void sbt16_mono(float *sample, short *pcm, int n)
{
   int i;

   for (i = 0; i < n; i++)
   {
      fdct16(sample, vbuf + vb_ptr);
      window16(vbuf, vb_ptr, pcm);
      sample += 64;
      vb_ptr = (vb_ptr - 16) & 255;
      pcm += 16;
   }


}
/*------------------------------------------------------------*/
void sbt16_dual(float *sample, short *pcm, int n)
{
   int i;

   for (i = 0; i < n; i++)
   {
      fdct16_dual(sample, vbuf + vb_ptr);
      fdct16_dual(sample + 1, vbuf2 + vb_ptr);
      window16_dual(vbuf, vb_ptr, pcm);
      window16_dual(vbuf2, vb_ptr, pcm + 1);
      sample += 64;
      vb_ptr = (vb_ptr - 16) & 255;
      pcm += 32;
   }
}
/*------------------------------------------------------------*/
void sbt16_dual_mono(float *sample, short *pcm, int n)
{
   int i;

   for (i = 0; i < n; i++)
   {
      fdct16_dual_mono(sample, vbuf + vb_ptr);
      window16(vbuf, vb_ptr, pcm);
      sample += 64;
      vb_ptr = (vb_ptr - 16) & 255;
      pcm += 16;
   }
}
/*------------------------------------------------------------*/
void sbt16_dual_left(float *sample, short *pcm, int n)
{
   int i;

   for (i = 0; i < n; i++)
   {
      fdct16_dual(sample, vbuf + vb_ptr);
      window16(vbuf, vb_ptr, pcm);
      sample += 64;
      vb_ptr = (vb_ptr - 16) & 255;
      pcm += 16;
   }
}
/*------------------------------------------------------------*/
void sbt16_dual_right(float *sample, short *pcm, int n)
{
   int i;

   sample++;
   for (i = 0; i < n; i++)
   {
      fdct16_dual(sample, vbuf + vb_ptr);
      window16(vbuf, vb_ptr, pcm);
      sample += 64;
      vb_ptr = (vb_ptr - 16) & 255;
      pcm += 16;
   }
}
/*------------------------------------------------------------*/
/*---------------- 8 pt sbt's  -------------------------------*/
/*------------------------------------------------------------*/
void sbt8_mono(float *sample, short *pcm, int n)
{
   int i;

   for (i = 0; i < n; i++)
   {
      fdct8(sample, vbuf + vb_ptr);
      window8(vbuf, vb_ptr, pcm);
      sample += 64;
      vb_ptr = (vb_ptr - 8) & 127;
      pcm += 8;
   }

}
/*------------------------------------------------------------*/
void sbt8_dual(float *sample, short *pcm, int n)
{
   int i;

   for (i = 0; i < n; i++)
   {
      fdct8_dual(sample, vbuf + vb_ptr);
      fdct8_dual(sample + 1, vbuf2 + vb_ptr);
      window8_dual(vbuf, vb_ptr, pcm);
      window8_dual(vbuf2, vb_ptr, pcm + 1);
      sample += 64;
      vb_ptr = (vb_ptr - 8) & 127;
      pcm += 16;
   }
}
/*------------------------------------------------------------*/
void sbt8_dual_mono(float *sample, short *pcm, int n)
{
   int i;

   for (i = 0; i < n; i++)
   {
      fdct8_dual_mono(sample, vbuf + vb_ptr);
      window8(vbuf, vb_ptr, pcm);
      sample += 64;
      vb_ptr = (vb_ptr - 8) & 127;
      pcm += 8;
   }
}
/*------------------------------------------------------------*/
void sbt8_dual_left(float *sample, short *pcm, int n)
{
   int i;

   for (i = 0; i < n; i++)
   {
      fdct8_dual(sample, vbuf + vb_ptr);
      window8(vbuf, vb_ptr, pcm);
      sample += 64;
      vb_ptr = (vb_ptr - 8) & 127;
      pcm += 8;
   }
}
/*------------------------------------------------------------*/
void sbt8_dual_right(float *sample, short *pcm, int n)
{
   int i;

   sample++;
   for (i = 0; i < n; i++)
   {
      fdct8_dual(sample, vbuf + vb_ptr);
      window8(vbuf, vb_ptr, pcm);
      sample += 64;
      vb_ptr = (vb_ptr - 8) & 127;
      pcm += 8;
   }
}
/*------------------------------------------------------------*/
/*------------------------------------------------------------*/
#include "csbtb.c"		/* 8 bit output */
#include "csbtL3.c"		/* Layer III */
/*------------------------------------------------------------*/