#pragma once
#include <stdint.h>

#pragma pack(push, 1)

enum {
    OPM_FORMAT_VERSION = 0x0010
};

struct opm_header_stream_desc_t {
    //uint16_t    ptr;        // offset to data stream in paragraphs (bytes*16)
    uint16_t    size;       // stream data size in bytes (max. 65520 bytes)
};

enum {
    OPM_CHIPTYPE_OPL    = (0 << 0),
    OPM_CHIPTYPE_OPN    = (1 << 0),
};

enum {
    OPM_FLAG_CHIP_OPN       = (0 << 0),
    OPM_FLAG_CHIP_OPN_DUAL  = (1 << 0),
    OPM_FLAG_CHIP_OPNA      = (2 << 0),
    OPM_FLAG_CHIP_OPN3      = (3 << 0),

    OPM_FLAG_CHIP_TYPE      = (3 << 0),
};

struct opm_header_t {
    char    magic[4];       // "OPM\x1A"
    union {
        struct {
            uint8_t minor;
            uint8_t major;
        };
        uint16_t v;
    } version;
    uint8_t     chip_type;          // see above
    uint8_t     reserved0;          //
    uint32_t    clock_rate;         // hz, integer
    uint16_t    frame_rate;         // hz, 8.8 fixedpoint
    uint16_t    flags;              // see above
    uint8_t     callstack_depth;    // reserved, 0 at this moment
    uint8_t     streams;            // including control streams
    uint32_t    stream_mask;        // used channel mask, LSB = ch 0

    // opm_header_stream_desc_t stream[opm_header_t::channels];  // first is control stream
};

// OPM v0 stream data, stream-independent commands
enum {
    OPM_STREAM_END_FRAME        = 0xFF,     // end of frame, next channel
    OPM_STREAM_END              = 0xFE,     // end of stream, stop here or loop to OPM_STREAM_LOOP stream point
    OPM_STREAM_NOP              = 0xFD,
    OPM_STREAM_NEW_ORDER        = 0xFC,     // nop, marks new order
    OPM_STREAM_SET_FRAME_RATE   = 0xFB,     // word rate (as in opm_header_t::frame_rate)
    OPM_STREAM_LOOP             = 0xFA,     // set loop point here

    // delay commands
    OPM_STREAM_DELAY_INT32      = 0xF9,     // dword delay
    OPM_STREAM_DELAY_INT16      = 0xF8,     // word  delay
    OPM_STREAM_DELAY_INT12      = 0xD0,     // D0..DF - 0..4095 frames delay (hibyte in low 4 bits of command)
    OPM_STERAM_DELAY_SHORT      = 0xC0,     // C0..CF - 1..16 frames delay

    // back reference 
    OPM_STREAM_BACKREF          = 0xE0,     // E0..EF - word backrefpos (12 bit), byte frames
};

// OPN control stream commands
enum {
    OPM_CTRL_EXTCH3             = 0x00,     // 00..7F - ext. CH3 op1-3 frequency
    OPM_CTRL_TIMER_CSM          = 0x80,     // 80..9F - set timer/CSM/LFO frequency
    OPM_CTRL_RHYTHM             = 0xA0,     // A0..BF - rhythm control

    OPM_CTRL_CMD80_REG24        = (1 << 0),
    OPM_CTRL_CMD80_REG25        = (1 << 1),
    OPM_CTRL_CMD80_REG27        = (1 << 2),
    OPM_CTRL_CMD80_REG22        = (1 << 3),
    OPM_CTRL_CMD80_EOF          = (1 << 4),

    OPM_CTRL_EXTCH3_OP1_LOW     = (1 << 0),
    OPM_CTRL_EXTCH3_OP1_HIGH    = (1 << 1),
    OPM_CTRL_EXTCH3_OP2_LOW     = (1 << 2),
    OPM_CTRL_EXTCH3_OP2_HIGH    = (1 << 3),
    OPM_CTRL_EXTCH3_OP3_LOW     = (1 << 4),
    OPM_CTRL_EXTCH3_OP3_HIGH    = (1 << 5),
    OPM_CTRL_EXTCH3_EOF         = (1 << 6),

    OPM_CTRL_CMDA0_REG_MASK     = (0x0F << 0),
    OPM_CTRL_CMDA0_EOF          = (1 << 4),
};

// OPN FM stream commands
enum {
    OPM_FM_ADSR                 = 0x00,     // 00..3F - set ADSR
    OPM_FM_MUL_TL_EG            = 0x40,     // 40..7F - set MULT/TL/SSG-EG
    OPM_FM_FREQ_FB_PAN          = 0x80,     // 80..9F - set frequency/feedback/panning
    OPM_FM_KEY                  = 0xA0,     // A0..BF - key on/off

    OPM_FM_CMD00_REG50          = (1 << 0),
    OPM_FM_CMD00_REG60          = (1 << 1),
    OPM_FM_CMD00_REG70          = (1 << 2),
    OPM_FM_CMD00_REG80          = (1 << 3),
    OPM_FM_CMD00_OP_SHIFT       = 4,
    OPM_FM_CMD00_OP_MASK        = (3 << OPM_FM_CMD00_OP_SHIFT),

    OPM_FM_CMD40_REG30          = (1 << 0),
    OPM_FM_CMD40_REG40          = (1 << 1),
    OPM_FM_CMD40_REG90          = (1 << 2),
    OPM_FM_CMD40_EOF            = (1 << 3),
    OPM_FM_CMD40_OP_SHIFT       = OPM_FM_CMD00_OP_SHIFT,
    OPM_FM_CMD40_OP_MASK        = OPM_FM_CMD00_OP_MASK,

    OPM_FM_CMD80_REGA0          = (1 << 0),
    OPM_FM_CMD80_REGA4          = (1 << 1),
    OPM_FM_CMD80_REGB0          = (1 << 2),
    OPM_FM_CMD80_REGB4          = (1 << 3),
    OPM_FM_CMD80_EOF            = (1 << 4),

    OPM_FM_CMDA0_OP_SHIFT       = 0,
    OPM_FM_CMDA0_OP_MASK        = (0x0F << OPM_FM_CMDA0_OP_SHIFT),
    OPM_FM_CMDA0_EOF            = (1 << 4),
};

// OPN SSG tone stream commands (shared with AY chip type)
enum {
    OPM_AYTONE_REGS             = 0x00,     // 00..7F - set volume and period low
    OPM_AYTONE_PERIOD           = 0x80,     // 80..BF - set period
    OPM_AYTONE_MASK             = 0xF0,     // F0..F7 - set tone/noise mask

    OPM_AYTONE_CMD00_VOLUME_MASK = (0x1F << 0),
    OPM_AYTONE_CMD00_PERIOD_LOW = (1 << 5),
    OPM_AYTONE_CMD00_EOF        = (1 << 6),

    OPM_AYTONE_CMD80_PERIOD_HIGH = (0xF << 0),
    OPM_AYTONE_CMD80_PERIOD_LOW = (1 << 4),
    OPM_AYTONE_CMD80_EOF        = (1 << 5),

    OPM_AYTONE_MASK_TONE        = (1 << 0),
    OPM_AYTONE_MASK_NOISE       = (1 << 1),
    OPM_AYTONE_MASK_EOF         = (1 << 2),
};

// OPN SSG envelope/noise stream commands (shared with AY chip type)
enum {
    OPM_AYENV_REGS              = 0x00,     // 00..7F - set noise and period low
    OPM_AYENV_ENVTYPE           = 0x80,     // 80..BF - set env type and period low
    OPM_AYENV_PERIOD_FULL       = 0xF0,     // F0..F7 - set full envelope period

    OPM_AYENV_CMD00_NOISE_MASK  = (0x1F << 0),
    OPM_AYENV_CMD00_PERIOD_LOW  = (1 << 5),
    OPM_AYENV_CMD00_EOF         = (1 << 6),

    OPM_AYENV_CMD80_ENV_TYPE    = (0xF << 0),
    OPM_AYENV_CMD80_PERIOD_LOW  = (1 << 4),
    OPM_AYENV_CMD80_EOF         = (1 << 5),

    OPM_AYENV_CMDF0_PERIOD_LOW  = (1 << 0),
    OPM_AYENV_CMDF0_PERIOD_HIGH = (1 << 1),
    OPM_AYENV_CMDF0_EOF         = (1 << 2),
};


#pragma pack(pop)