/*
    HuC6280 sound chip emulator
    by Charles MacDonald
    E-mail: cgfm2@hotmail.com
    WWW: http://cgfm2.emuviews.com

    Thanks to:

    - Paul Clifford for his PSG documentation.
    - Richard Bannister for the TGEmu-specific sound updating code.
    - http://www.uspto.gov for the PSG patents.
    - All contributors to the tghack-list.

    Changes:

    (03/30/2003)
    - Removed TGEmu specific code and added support functions for MAME.
    - Modified setup code to handle multiple chips with different clock and
      volume settings.

    Missing features / things to do:

    - Add LFO support. But do any games actually use it?

    - Add shared index for waveform playback and sample writes. Almost every
      game will reset the index prior to playback so this isn't an issue.

    - While the noise emulation is complete, the data for the pseudo-random
      bitstream is calculated by rand() and is not a representation of what
      the actual hardware does.

    For some background on Hudson Soft's C62 chipset:

    - http://www.hudsonsoft.net/ww/about/about.html
    - http://www.hudson.co.jp/corp/eng/coinfo/history.html

    Legal information:

    Copyright (C) 2002, 2003  Charles MacDonald

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

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

#include "driver.h"
#include "state.h"
#include "c6280.h"

/* Local function prototypes */
void c6280_init(c6280_t *p, double clk, double rate);
void c6280_write(c6280_t *p, int offset, int data);
void c6280_update(void *param, stream_sample_t **inputs, stream_sample_t **buffer, int length);


void c6280_init(c6280_t *p, double clk, double rate)
{
    int i;
    double step;

    /* Loudest volume level for table */
    double level = 65535.0 / 6.0 / 32.0;

    /* Clear context */
    memset(p, 0, sizeof(c6280_t));

    /* Make waveform frequency table */
    for(i = 0; i < 4096; i += 1)
    {
        step = ((clk / rate) * 4096) / (i+1);
        p->wave_freq_tab[(1 + i) & 0xFFF] = (UINT32)step;
    }

    /* Make noise frequency table */
    for(i = 0; i < 32; i += 1)
    {
        step = ((clk / rate) * 32) / (i+1);
        p->noise_freq_tab[i] = (UINT32)step;
    }

    /* Make volume table */
    /* PSG has 48dB volume range spread over 32 steps */
    step = 48.0 / 32.0;
    for(i = 0; i < 31; i++)
    {
        p->volume_table[i] = (UINT16)level;
        level /= pow(10.0, step / 20.0);
    }
    p->volume_table[31] = 0;
}


void c6280_write(c6280_t *p, int offset, int data)
{
    t_channel *q = &p->channel[p->select];

    /* Update stream */
    stream_update(p->stream, 0);

    switch(offset & 0x0F)
    {
        case 0x00: /* Channel select */
            p->select = data & 0x07;
            break;

        case 0x01: /* Global balance */
            p->balance  = data;
            break;

        case 0x02: /* Channel frequency (LSB) */
            q->frequency = (q->frequency & 0x0F00) | data;
            q->frequency &= 0x0FFF;
            break;

        case 0x03: /* Channel frequency (MSB) */
            q->frequency = (q->frequency & 0x00FF) | (data << 8);
            q->frequency &= 0x0FFF;
            break;

        case 0x04: /* Channel control (key-on, DDA mode, volume) */

            /* 1-to-0 transition of DDA bit resets waveform index */
            if((q->control & 0x40) && ((data & 0x40) == 0))
            {
                q->index = 0;
            }
            q->control = data;
            break;

        case 0x05: /* Channel balance */
            q->balance = data;
            break;

        case 0x06: /* Channel waveform data */

            switch(q->control & 0xC0)
            {
                case 0x00:
                    q->waveform[q->index & 0x1F] = data & 0x1F;
                    q->index = (q->index + 1) & 0x1F;
                    break;

                case 0x40:
                    break;

                case 0x80:
                    q->waveform[q->index & 0x1F] = data & 0x1F;
                    q->index = (q->index + 1) & 0x1F;
                    break;

                case 0xC0:
                    q->dda = data & 0x1F;
                    break;
            }

            break;

        case 0x07: /* Noise control (enable, frequency) */
            q->noise_control = data;
            break;

        case 0x08: /* LFO frequency */
            p->lfo_frequency = data;
            break;

        case 0x09: /* LFO control (enable, mode) */
            p->lfo_control = data;
            break;

        default:
            break;
    }
}


void c6280_update(void *param, stream_sample_t **inputs, stream_sample_t **buffer, int length)
{
    static int scale_tab[] = {
        0x00, 0x03, 0x05, 0x07, 0x09, 0x0B, 0x0D, 0x0F,
        0x10, 0x13, 0x15, 0x17, 0x19, 0x1B, 0x1D, 0x1F
    };
    int ch;
    int i;
    c6280_t *p = param;

    int lmal = (p->balance >> 4) & 0x0F;
    int rmal = (p->balance >> 0) & 0x0F;
    int vll, vlr;

    lmal = scale_tab[lmal];
    rmal = scale_tab[rmal];

    /* Clear buffer */
    for(i = 0; i < length; i++)
    {
        buffer[0][i] = 0;
        buffer[1][i] = 0;
    }

    for(ch = 0; ch < 6; ch++)
    {
        /* Only look at enabled channels */
        if(p->channel[ch].control & 0x80)
        {
            int lal = (p->channel[ch].balance >> 4) & 0x0F;
            int ral = (p->channel[ch].balance >> 0) & 0x0F;
            int al  = p->channel[ch].control & 0x1F;

            lal = scale_tab[lal];
            ral = scale_tab[ral];

            /* Calculate volume just as the patent says */
            vll = (0x1F - lal) + (0x1F - al) + (0x1F - lmal);
            if(vll > 0x1F) vll = 0x1F;

            vlr = (0x1F - ral) + (0x1F - al) + (0x1F - rmal);
            if(vlr > 0x1F) vlr = 0x1F;

            vll = p->volume_table[vll];
            vlr = p->volume_table[vlr];

            /* Check channel mode */
            if((ch >= 4) && (p->channel[ch].noise_control & 0x80))
            {
                /* Noise mode */
                UINT32 step = p->noise_freq_tab[(p->channel[ch].noise_control & 0x1F) ^ 0x1F];
                for(i = 0; i < length; i += 1)
                {
                    static int data = 0;
                    p->channel[ch].noise_counter += step;
                    if(p->channel[ch].noise_counter >= 0x800)
                    {
                        data = (rand() & 1) ? 0x1F : 0;
                    }
                    p->channel[ch].noise_counter &= 0x7FF;
                    buffer[0][i] += (INT16)(vll * (data - 16));
                    buffer[1][i] += (INT16)(vlr * (data - 16));
                }
            }
            else
            if(p->channel[ch].control & 0x40)
            {
                /* DDA mode */
                for(i = 0; i < length; i++)
                {
                    buffer[0][i] += (INT16)(vll * (p->channel[ch].dda - 16));
                    buffer[1][i] += (INT16)(vlr * (p->channel[ch].dda - 16));
                }
            }
            else
            {
                /* Waveform mode */
                UINT32 step = p->wave_freq_tab[p->channel[ch].frequency];
                for(i = 0; i < length; i += 1)
                {
                    int offset;
                    INT16 data;
                    offset = (p->channel[ch].counter >> 12) & 0x1F;
                    p->channel[ch].counter += step;
                    p->channel[ch].counter &= 0x1FFFF;
                    data = p->channel[ch].waveform[offset];
                    buffer[0][i] += (INT16)(vll * (data - 16));
                    buffer[1][i] += (INT16)(vlr * (data - 16));
                }
            }
        }
    }
}


/*--------------------------------------------------------------------------*/
/* MAME specific code                                                       */
/*--------------------------------------------------------------------------*/

static void *c6280_start(int sndindex, int clock, const void *config)
{
    c6280_t *info;

    info = auto_malloc(sizeof(*info));
    memset(info, 0, sizeof(*info));

   /* Initialize PSG emulator */
   c6280_init(info, clock, Machine->sample_rate);

   /* Create stereo stream */
   info->stream = stream_create(0, 2, Machine->sample_rate, info, c6280_update);

    return info;
}

WRITE8_HANDLER( C6280_0_w ) {  c6280_write(sndti_token(SOUND_C6280, 0),offset,data); }
WRITE8_HANDLER( C6280_1_w ) {  c6280_write(sndti_token(SOUND_C6280, 1),offset,data); }



/**************************************************************************
 * Generic get_info
 **************************************************************************/

static void c6280_set_info(void *token, UINT32 state, union sndinfo *info)
{
	switch (state)
	{
		/* no parameters to set */
	}
}


void c6280_get_info(void *token, UINT32 state, union sndinfo *info)
{
	switch (state)
	{
		/* --- the following bits of info are returned as 64-bit signed integers --- */

		/* --- the following bits of info are returned as pointers to data or functions --- */
		case SNDINFO_PTR_SET_INFO:						info->set_info = c6280_set_info;		break;
		case SNDINFO_PTR_START:							info->start = c6280_start;				break;
		case SNDINFO_PTR_STOP:							/* nothing */							break;
		case SNDINFO_PTR_RESET:							/* nothing */							break;

		/* --- the following bits of info are returned as NULL-terminated strings --- */
		case SNDINFO_STR_NAME:							info->s = "HuC6280";					break;
		case SNDINFO_STR_CORE_FAMILY:					info->s = "????";						break;
		case SNDINFO_STR_CORE_VERSION:					info->s = "1.0";						break;
		case SNDINFO_STR_CORE_FILE:						info->s = __FILE__;						break;
		case SNDINFO_STR_CORE_CREDITS:					info->s = "Copyright (c) 2004, The MAME Team"; break;
	}
}

