/////////////////////////////////////////////////////////////////////////
// $Id$
/////////////////////////////////////////////////////////////////////////
/*
 *  Copyright (C) 2002-2013  The DOSBox Team
 *  Copyright (C) 2015-2021  The Bochs Project
 *  OPL2/OPL3 emulation library
 *
 *  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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */


/*
 * Originally based on ADLIBEMU.C, an AdLib/OPL2 emulation library by Ken Silverman
 * Copyright (C) 1998-2001 Ken Silverman
 * Ken Silverman's official web site: "http://www.advsys.net/ken"
 */

#if BX_SUPPORT_SB16

#define OPLTYPE_IS_OPL3

#define fltype double

/*
  define Bits, Bitu here
*/
typedef Bit64u    Bitu;
typedef Bit64s    Bits;


#ifdef OPL_SOURCE

/*
  define attribution that inlines/forces inlining of a function (optional)
*/
#define OPL_INLINE BX_CPP_INLINE


#undef NUM_CHANNELS
#if defined(OPLTYPE_IS_OPL3)
#define NUM_CHANNELS  18
#else
#define NUM_CHANNELS  9
#endif

#define MAXOPERATORS  (NUM_CHANNELS*2)


#define FL05  ((fltype)0.5)
#define FL2   ((fltype)2.0)
#define PI    ((fltype)3.1415926535897932384626433832795)


#define FIXEDPT     0x10000    // fixed-point calculations using 16+16
#define FIXEDPT_LFO 0x1000000  // fixed-point calculations using 8+24

#define WAVEPREC    1024       // waveform precision (10 bits)

#define INTFREQU    ((fltype)(14318180.0 / 288.0)) // clocking of the chip

enum {
  OF_TYPE_ATT = 0,
  OF_TYPE_DEC = 1,
  OF_TYPE_REL = 2,
  OF_TYPE_SUS = 3,
  OF_TYPE_SUS_NOKEEP = 4,
  OF_TYPE_OFF = 5
};

#define ARC_CONTROL     0x00
#define ARC_TVS_KSR_MUL 0x20
#define ARC_KSL_OUTLEV  0x40
#define ARC_ATTR_DECR   0x60
#define ARC_SUSL_RELR   0x80
#define ARC_FREQ_NUM    0xa0
#define ARC_KON_BNUM    0xb0
#define ARC_PERC_MODE   0xbd
#define ARC_FEEDBACK    0xc0
#define ARC_WAVE_SEL    0xe0

#define ARC_SECONDSET   0x100 // second operator set for OPL3

#define OP_ACT_OFF      0x00
#define OP_ACT_NORMAL   0x01  // regular channel activated (bitmasked)
#define OP_ACT_PERC     0x02  // percussion channel activated (bitmasked)

#define BLOCKBUF_SIZE   512


// vibrato constants
#define VIBTAB_SIZE      8
#define VIBFAC        70/50000 // no braces, integer mul/div

// tremolo constants and table
#define TREMTAB_SIZE  53
#define TREM_FREQ     ((fltype)(3.7)) // tremolo at 3.7hz


/* operator struct definition
     For OPL2 all 9 channels consist of two operators each, carrier and modulator.
     Channel x has operators x as modulator and operators (9+x) as carrier.
     For OPL3 all 18 channels consist either of two operators (2op mode) or four
     operators (4op mode) which is determined through register4 of the second
     adlib register set.
     Only the channels 0,1,2 (first set) and 9,10,11 (second set) can act as
     4op channels. The two additional operators for a channel y come from the
     2op channel y+3 so the operatorss y, (9+y), y+3, (9+y)+3 make up a 4op
     channel.
*/
typedef struct operator_struct {
  Bit32s cval, lastcval;   // current output/last output (used for feedback)
  Bit32u tcount, wfpos, tinc;    // time (position in waveform) and time increment
  fltype amp, step_amp;    // and amplification (envelope)
  fltype vol;              // volume
  fltype sustain_level;    // sustain level
  Bit32s mfbi;             // feedback amount
  fltype a0, a1, a2, a3;   // attack rate function coefficients
  fltype decaymul, releasemul;  // decay/release rate functions
  Bit32u op_state;         // current state of operator (attack/decay/sustain/release/off)
  Bit32u toff;
  Bit32s freq_high;        // highest three bits of the frequency, used for vibrato calculations
  Bit8u cur_wvsel;         // register value of selected waveform
  Bit16s* cur_wform;       // start of selected waveform
  Bit32u cur_wmask;        // mask for selected waveform
  Bit32u act_state;        // activity state (regular, percussion)
  bool sus_keep;           // keep sustain level when decay finished
  bool vibrato,tremolo;    // vibrato/tremolo enable bits

  // variables used to provide non-continuous envelopes
  Bit32u generator_pos;    // for non-standard sample rates we need to determine how many samples have passed
  Bits cur_env_step;       // current (standardized) sample position
  Bits env_step_a,env_step_d,env_step_r;  // number of std samples of one step (for attack/decay/release mode)
  Bit8u step_skip_pos_a;   // position of 8-cyclic step skipping (always 2^x to check against mask)
  Bits env_step_skip_a;    // bitmask that determines if a step is skipped (respective bit is zero then)

#if defined(OPLTYPE_IS_OPL3)
  bool is_4op,is_4op_attached;    // base of a 4op channel/part of a 4op channel
  Bit32s left_pan,right_pan;      // opl3 stereo panning amount
#endif
} op_type;

// per-chip variables
Bitu chip_num;
op_type op[MAXOPERATORS];

Bits int_samplerate;

Bit8u status;
#if defined(OPLTYPE_IS_OPL3)
Bit8u adlibreg[512];  // adlib register set (including second set)
Bit8u wave_sel[44];    // waveform selection
#else
Bit8u adlibreg[256];  // adlib register set
Bit8u wave_sel[22];    // waveform selection
#endif


// vibrato/tremolo increment/counter
Bit32u vibtab_pos;
Bit32u vibtab_add;
Bit32u tremtab_pos;
Bit32u tremtab_add;


// enable an operator
void enable_operator(Bitu regbase, op_type* op_pt);

// functions to change parameters of an operator
void change_frequency(Bitu chanbase, Bitu regbase, op_type* op_pt);

void change_attackrate(Bitu regbase, op_type* op_pt);
void change_decayrate(Bitu regbase, op_type* op_pt);
void change_releaserate(Bitu regbase, op_type* op_pt);
void change_sustainlevel(Bitu regbase, op_type* op_pt);
void change_waveform(Bitu regbase, op_type* op_pt);
void change_keepsustain(Bitu regbase, op_type* op_pt);
void change_vibrato(Bitu regbase, op_type* op_pt);
void change_feedback(Bitu chanbase, op_type* op_pt);

static Bit32u generator_add; // should be a chip parameter
#endif // OPL_SOURCE

// general functions
void adlib_init(Bit32u samplerate);
void adlib_write(Bitu idx, Bit8u val);
bool adlib_getsample(Bit16u rate, Bit16s* sndptr, Bits numsamples, Bit16u volume);

Bitu adlib_reg_read(Bitu port);
void adlib_write_index(Bitu port, Bit8u val);

void adlib_register_state(bx_list_c *parent);
void adlib_after_restore_state();

extern Bit16u opl_index;

#endif
