/*************************************************************************/
/*                                                                       */
/*                  Language Technologies Institute                      */
/*                     Carnegie Mellon University                        */
/*                        Copyright (c) 2000                             */
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/*  THIS SOFTWARE.                                                       */
/*                                                                       */
/*************************************************************************/
/*             Author:  Alan W Black (awb@cs.cmu.edu)                    */
/*               Date:  October 2000                                     */
/*************************************************************************/
/*                                                                       */
/*  Convertion routines for various waveform encodings                   */
/*                                                                       */
/*  This contains software written external to Flite                     */
/*       ulaw code came via the Edinburgh Speech Tools                   */
/*  g72x codec came from Sun Microsystems                                */
/*                                                                       */
/*************************************************************************/

#include "g72x.h"

/*
** This routine converts from linear to ulaw.
**
** Craig Reese: IDA/Supercomputing Research Center
** Joe Campbell: Department of Defense
** 29 September 1989
**
** References:
** 1) CCITT Recommendation G.711  (very difficult to follow)
** 2) "A New Digital Technique for Implementation of Any
**     Continuous PCM Companding Law," Villeret, Michel,
**     et al. 1973 IEEE Int. Conf. on Communications, Vol 1,
**     1973, pg. 11.12-11.17
** 3) MIL-STD-188-113,"Interoperability and Performance Standards
**     for Analog-to_Digital Conversion Techniques,"
**     17 February 1987
**
** Input: Signed 16 bit linear sample
** Output: 8 bit ulaw sample
*/

#define ZEROTRAP    /* turn on the trap as per the MIL-STD */
#define BIAS 0x84   /* define the add-in bias for 16 bit samples */
#define CLIP 32635

unsigned char cst_short_to_ulaw(short sample)
{
    static const int exp_lut[256] = {0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,
				   4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
				   5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
				   5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
				   6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
				   6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
				   6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
				   6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
				   7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
				   7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
				   7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
				   7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
				   7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
				   7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
				   7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
				   7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7};
    int sign, exponent, mantissa;
    unsigned char ulawbyte;

    /* Get the sample into sign-magnitude. */
    sign = (sample >> 8) & 0x80; /* set aside the sign */
    if ( sign != 0 ) sample = -sample; /* get magnitude */
    if ( sample > CLIP ) sample = CLIP; /* clip the magnitude */

    /* Convert from 16 bit linear to ulaw. */
    sample = sample + BIAS;
    exponent = exp_lut[( sample >> 7 ) & 0xFF];
    mantissa = ( sample >> ( exponent + 3 ) ) & 0x0F;
    ulawbyte = ~ ( sign | ( exponent << 4 ) | mantissa );
#ifdef ZEROTRAP
    if ( ulawbyte == 0 ) ulawbyte = 0x02; /* optional CCITT trap */
#endif

    return ulawbyte;
}

/*
** This routine converts from ulaw to 16 bit linear.
**
** Craig Reese: IDA/Supercomputing Research Center
** 29 September 1989
**
** References:
** 1) CCITT Recommendation G.711  (very difficult to follow)
** 2) MIL-STD-188-113,"Interoperability and Performance Standards
**     for Analog-to_Digital Conversion Techniques,"
**     17 February 1987
**
** Input: 8 bit ulaw sample
** Output: signed 16 bit linear sample
*/

short cst_ulaw_to_short( unsigned char ulawbyte )
{
    static const int exp_lut[8] = { 0, 132, 396, 924, 1980, 4092, 8316, 16764 };
    int sign, exponent, mantissa;
    short sample;

    ulawbyte = ~ ulawbyte;
    sign = ( ulawbyte & 0x80 );
    exponent = ( ulawbyte >> 4 ) & 0x07;
    mantissa = ulawbyte & 0x0F;
    sample = exp_lut[exponent] + ( mantissa << ( exponent + 3 ) );
    if ( sign != 0 ) sample = -sample;

    return sample;
}


unsigned char *cst_g721_decode(int *actual_size,int size, 
                       const unsigned char *packed_residual
                       )
{
    struct g72x_state state;
    short sample_short;
    unsigned char *unpacked_residual;
    unsigned char code, xcode;
    int ur=0;
    int dec_bits;

    *actual_size = size*2;
    unpacked_residual = cst_alloc(unsigned char, *actual_size);
    g72x_init_state(&state);
    dec_bits = 4; /* g721 4-bit encoding */

    for (ur=0; ur <*actual_size; ur++)
    {
        xcode = packed_residual[ur/2];
        if (ur % 2 == 0)
            code = (xcode & 0xF0) >> dec_bits;
        else
            code = (xcode & 0x0F);
        sample_short = g721_decoder(code,AUDIO_ENCODING_LINEAR,&state);
        unpacked_residual[ur] = cst_short_to_ulaw(sample_short);
    }

    return unpacked_residual;
}

unsigned char *cst_g721_encode(int *packed_size,int actual_size, 
                               const unsigned char *unpacked_residual
                               )
{
    struct g72x_state state;
    unsigned char *packed_residual;
    unsigned char code, xcode=0;
    int ur=0;
    int dec_bits;

    *packed_size = (actual_size+1)/2; /* will round down to even number */
    packed_residual = cst_alloc(unsigned char, *packed_size);

    g72x_init_state(&state);
    dec_bits = 4; /* g721 4-bit encoding */

    for (ur=0; ur < actual_size; ur++)
    {
        code = g721_encoder((int)cst_ulaw_to_short(unpacked_residual[ur]),
                            AUDIO_ENCODING_LINEAR,&state);
        if (ur % 2 == 0)
        {
            xcode = 0;
            xcode = code << dec_bits;
        }
        else
        {
            xcode += code;
            packed_residual[ur/2] = xcode;
        }
    }

    return packed_residual;

}