/*
    dos.c --
    DOS interface code for the emulator
*/

#include "osd.h"

#define FRAMES_PER_SECOND   60

RGB vdp_palette[3][0x200];
PALETTE gen_pal;
BITMAP *gen_bmp;

volatile int frame_skip      = 1;
volatile int frame_count     = 0;
volatile int frames_rendered = 0;
volatile int frame_rate      = 0;
volatile int tick_count      = 0;
volatile int old_tick_count  = 0;
volatile int skip            = 0;

int quit = 0;

int main (int argc, char *argv[])
{
    if(argc < 2) {
        printf("Genesis Plus - Sega Mega Drive emulator (v1.0)\n");
        printf("(C) 1999, 2000, 2001, 2002, 2003  Charles MacDonald\n");
        printf("Usage %s file.[bin|smd|zip] [-options]\n", argv[0]);
        printf("Type `%s -help' for a list of options.\n", argv[0]);
        exit(1);
    };

    if(stricmp(argv[1], "-help") == 0)
    {
        print_options();
        return (0);
    }
    
    if(!load_rom(argv[1]))
    {
        printf("File `%s' not found.\n", argv[1]);
        return (0);
    }

    init_machine();

    error_init();
    system_init();

    if(option.sound)
    {
        audio_init(option.sndrate);
    }

    system_reset();


    for(;;)
    {
        frame_count += 1;
        if(quit) break;
        dos_update_input();
        if(frame_count % frame_skip == 0)
        {
            system_frame(0);
            dos_update_video();
        }
        else
        {
            system_frame(1);
        }
        if(option.sound) dos_update_audio();
    }

    trash_machine();
    system_shutdown();
    error_shutdown();
    return (0);
}

/* Timer handler */
void tick_handler(void)
{
    tick_count += 1;
    if(tick_count % FRAMES_PER_SECOND == 0)
    {
        frame_rate = frames_rendered;
        frames_rendered = 0;
    }
}
END_OF_FUNCTION(tick_handler);


int load_file(char *filename, char *buf, int size)
{
    FILE *fd = fopen(filename, "rb");
    if(!fd) return (0);
    fread(buf, size, 1, fd);
    fclose(fd);
    return (1);
}

int save_file(char *filename, char *buf, int size)
{
    FILE *fd = NULL;
    if(!(fd = fopen(filename, "wb"))) return (0);
    fwrite(buf, size, 1, fd);
    fclose(fd);
    return (1);
}


void dos_update_input(void)
{
    if(key[KEY_ESC] || key[KEY_END])
    {
        quit = 1;
    }

    input.pad[0] = 0;

    /* Is the joystick being used ? */
    if(option.joy_driver != JOY_TYPE_NONE)
    {
        poll_joystick();

        /* Check player 1 joystick */
        if(joy[0].stick[0].axis[1].d1) input.pad[0] |= INPUT_UP;
        else
        if(joy[0].stick[0].axis[1].d2) input.pad[0] |= INPUT_DOWN;

        if(joy[0].stick[0].axis[0].d1) input.pad[0] |= INPUT_LEFT;
        else
        if(joy[0].stick[0].axis[0].d2) input.pad[0] |= INPUT_RIGHT;

        if(joy[0].button[0].b)  input.pad[0] |= INPUT_A;
        if(joy[0].button[1].b)  input.pad[0] |= INPUT_B;
        if(joy[0].button[2].b)  input.pad[0] |= INPUT_C;
        if(joy[0].button[3].b)  input.pad[0] |= INPUT_START;
        if(joy[0].button[4].b)  input.pad[0] |= INPUT_X;
        if(joy[0].button[5].b)  input.pad[0] |= INPUT_Y;
        if(joy[0].button[6].b)  input.pad[0] |= INPUT_Z;
        if(joy[0].button[7].b)  input.pad[0] |= INPUT_MODE;

        /* More than one joystick supported ? */
        if(num_joysticks > 2)
        {
            /* Check player 2 joystick */
            if(joy[1].stick[0].axis[1].d1) input.pad[1] |= INPUT_UP;
            else
            if(joy[1].stick[0].axis[1].d2) input.pad[1] |= INPUT_DOWN;

            if(joy[1].stick[0].axis[0].d1) input.pad[1] |= INPUT_LEFT;
            else
            if(joy[1].stick[0].axis[0].d1) input.pad[1] |= INPUT_RIGHT;

            if(joy[1].button[0].b)  input.pad[1] |= INPUT_A;
            if(joy[1].button[1].b)  input.pad[1] |= INPUT_B;
            if(joy[1].button[2].b)  input.pad[1] |= INPUT_C;
            if(joy[1].button[3].b)  input.pad[1] |= INPUT_START;
            if(joy[1].button[4].b)  input.pad[1] |= INPUT_X;
            if(joy[1].button[5].b)  input.pad[1] |= INPUT_Y;
            if(joy[1].button[6].b)  input.pad[1] |= INPUT_Z;
            if(joy[1].button[7].b)  input.pad[1] |= INPUT_MODE;
        }
    }

    if(key[KEY_UP])     input.pad[0] |= INPUT_UP;
    else
    if(key[KEY_DOWN])   input.pad[0] |= INPUT_DOWN;
    if(key[KEY_LEFT])   input.pad[0] |= INPUT_LEFT;
    else
    if(key[KEY_RIGHT])  input.pad[0] |= INPUT_RIGHT;

    if(key[KEY_A])      input.pad[0] |= INPUT_A;
    if(key[KEY_S])      input.pad[0] |= INPUT_B;
    if(key[KEY_D])      input.pad[0] |= INPUT_C;
    if(key[KEY_F])      input.pad[0] |= INPUT_START;
    if(key[KEY_Z])      input.pad[0] |= INPUT_X;
    if(key[KEY_X])      input.pad[0] |= INPUT_Y;
    if(key[KEY_C])      input.pad[0] |= INPUT_Z;
    if(key[KEY_V])      input.pad[0] |= INPUT_MODE;

    if(check_key(KEY_TAB))
        system_reset();

    if(check_key(KEY_F1)) frame_skip = 1;
    if(check_key(KEY_F2)) frame_skip = 2;
    if(check_key(KEY_F3)) frame_skip = 3;
    if(check_key(KEY_F4)) frame_skip = 4;
}

void dos_update_audio(void)
{
    osd_play_streamed_sample_16(option.swap ^ 0, snd.buffer[0], snd.buffer_size * 2, option.sndrate, FRAMES_PER_SECOND, -100);
    osd_play_streamed_sample_16(option.swap ^ 1, snd.buffer[1], snd.buffer_size * 2, option.sndrate, FRAMES_PER_SECOND,  100);
}

void dos_update_palette(void)
{
    if(is_border_dirty)
    {
        uint16 data = *(uint16 *)&cram[(border << 1)];
        RGB *color;

        is_border_dirty = 0;

        if(reg[12] & 8)
        {
            int j;
            for(j = 0; j < 3; j += 1)
            {
                color = &vdp_palette[j][data];
                set_color((j << 6), color);
            }
        }
        else
        {
            color = &vdp_palette[1][data];
            set_color(0x00, color);
            set_color(0x40, color);
            set_color(0x80, color);
        }
    }

    if(is_color_dirty)
    {
        int i;
        uint16 *p = (uint16 *)&cram[0];
        is_color_dirty = 0;

        for(i = 0; i < 64; i += 1)
        {
            if((color_dirty[i]) && ((i & 0x0F) != 0x00))
            {
                RGB *color;
                color_dirty[i] = 0;
                if(reg[12] & 8)
                {
                    int j;
                    for(j = 0; j < 3; j += 1)
                    {
                        color = &vdp_palette[j][p[i]];
                        set_color((j << 6) | i, color);
                    }
                }
                else
                {
                    color = &vdp_palette[1][p[i]];
                    set_color(0x00 | i, color);
                    set_color(0x40 | i, color);
                    set_color(0x80 | i, color);
                }
            }
        }
    }
}

void dos_update_video(void)
{
    int width = (reg[12] & 1) ? 320 : 256;
    int height = (reg[1] & 8) ? 240 : 224;
    int center_x = (SCREEN_W - width) / 2;
    int center_y = (SCREEN_H / (option.scanlines ? 4 : 2)) - (height / 2);

    /* Wait for VSync */
    if(option.vsync) vsync();

    if(bitmap.viewport.changed)
    {
        bitmap.viewport.changed = 0;
        if(bitmap.remap)
        {
            clear(screen);
        }
        else
        {
            clear_to_color(screen, 0xFF);
        }
    }

    if(bitmap.remap == 0)
    {
        dos_update_palette();
    }


    if(option.scanlines)
    {
        int y;
        for(y = 0; y < height; y += 1)
        {
            blit(gen_bmp, screen, 0x20, y, center_x, (center_y + y) << 1, width, 1);
        }
    }
    else
    {

        blit(gen_bmp, screen, 0x20, 0, center_x, center_y, width, height);
    }
}

void init_machine(void)
{
    do_config("gen.cfg");

    if(option.sound)
    {
        msdos_init_sound(&option.sndrate, option.sndcard);
    }

    allegro_init();
    install_keyboard();
    install_joystick(option.joy_driver);

    install_timer();
    LOCK_FUNCTION(tick_handler);
    LOCK_VARIABLE(tick_count);
    LOCK_VARIABLE(frame_rate);
    install_int_ex(tick_handler, BPS_TO_TIMER(FRAMES_PER_SECOND));

    set_color_depth(option.video_depth);
    gen_bmp = create_bitmap(512, 512);
    clear(gen_bmp);

    memset(&bitmap, 0, sizeof(bitmap));
    bitmap.data = (uint8 *)&gen_bmp->line[0][0];
    bitmap.width = gen_bmp->w;
    bitmap.height = gen_bmp->h;
    bitmap.depth = option.video_depth;
    switch(option.video_depth)
    {
        case 8:
            bitmap.granularity = 1;
            break;
        case 15:
            bitmap.granularity = 2;
            break;
        case 16:
            bitmap.granularity = 2;
            break;
        case 32:
            bitmap.granularity = 4;
            break;
    }
    bitmap.pitch = (bitmap.width * bitmap.granularity);
    bitmap.viewport.w = 256;
    bitmap.viewport.h = 224;
    bitmap.viewport.x = 0x20;
    bitmap.viewport.y = 0x00;
    bitmap.remap = 0;
    if(option.remap) bitmap.remap = 1;
    else
    if(bitmap.depth > 8) bitmap.remap = 1;

    make_vdp_palette();

    memcpy(gen_pal, black_palette, sizeof(PALETTE));
    gen_pal[0xFE].r = \
    gen_pal[0xFE].g = \
    gen_pal[0xFE].b = 0x3F;

    dos_change_mode();
}

void trash_machine(void)
{
    if(option.sound)
    {
        msdos_shutdown_sound();
    }
    clear(screen);
    destroy_bitmap(gen_bmp);
    set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
}

void make_vdp_palette(void)
{
    uint8 lut[3][8] =
    {
        {0x00, 0x04, 0x08, 0x0C, 0x10, 0x14, 0x18, 0x1C},
        {0x00, 0x08, 0x10, 0x18, 0x20, 0x28, 0x30, 0x38},
        {0x20, 0x24, 0x28, 0x2C, 0x30, 0x34, 0x38, 0x3C},
    };

    int j;
    for(j = 0; j < 0x600; j += 1)
    {

        int r = (j >> 6) & 7;
        int g = (j >> 3) & 7;
        int b = (j >> 0) & 7;
        int i = (j >> 9) & 3;

        vdp_palette[i][j & 0x1FF].r = lut[i][r];
        vdp_palette[i][j & 0x1FF].g = lut[i][g];
        vdp_palette[i][j & 0x1FF].b = lut[i][b];
    }
}

void dos_change_mode(void)
{
    int ret;
    int width = option.video_width;
    int height = option.video_height;

    if(option.scanlines) height *= 2;
    ret = set_gfx_mode(option.video_driver, width, height, 0, 0);
    if(ret != 0)
    {
        set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
        printf("Error setting graphics mode (%dx%d %dbpp).\nAllegro says: `%s'\n", width, height, option.video_depth, allegro_error);
        exit(1);
    }

    if(bitmap.depth == 8)
    {
        if(bitmap.remap)
        {
            int i;
            for(i = 0; i < 0x100; i += 1)
            {                     
                gen_pal[i].r = ((i >> 5) & 7) << 3;
                gen_pal[i].g = ((i >> 2) & 7) << 3;
                gen_pal[i].b = ((i >> 0) & 3) << 4;
            }
        set_palette(gen_pal);
        }
        else
        {
            clear_to_color(screen, 0xFF);
            gen_pal[0xfe].r = 0xff;
            gen_pal[0xfe].g = 0xff;
            gen_pal[0xfe].b = 0xff;
            set_palette(gen_pal);
            inp(0x3DA);
            outp(0x3C0, 0x31);
            outp(0x3C0, 0xFF);
        }
    }
    else
    {
        clear(screen);
    }
}



/* Check if a key is pressed */
int check_key(int code)
{
    static char lastbuf[0x100] = {0};

    if((!key[code]) && (lastbuf[code] == 1))
        lastbuf[code] = 0;

    if((key[code]) && (lastbuf[code] == 0))
    {
        lastbuf[code] = 1;
        return (1);
    }                                                                    

    return (0);
}