/*
 * 86Box    A hypervisor and IBM PC system emulator that specializes in
 *          running old operating systems and software designed for IBM
 *          PC systems and compatibles from 1981 through fairly recent
 *          system designs based on the PCI bus.
 *
 *          This file is part of the 86Box distribution.
 *
 *          Emulation of the old and new IBM CGA graphics cards.
 *
 *
 *
 * Authors: Sarah Walker, <https://pcem-emulator.co.uk/>
 *          Miran Grca, <mgrca8@gmail.com>
 *
 *          Copyright 2008-2019 Sarah Walker.
 *          Copyright 2016-2019 Miran Grca.
 */
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <stdlib.h>
#include <wchar.h>
#include <math.h>
#include <86box/86box.h>
#include "cpu.h"
#include <86box/io.h>
#include <86box/timer.h>
#include <86box/pit.h>
#include <86box/mem.h>
#include <86box/rom.h>
#include <86box/device.h>
#include <86box/video.h>
#include <86box/vid_cga.h>
#include <86box/vid_cga_comp.h>

#define CGA_RGB       0
#define CGA_COMPOSITE 1

#define COMPOSITE_OLD 0
#define COMPOSITE_NEW 1

static uint8_t crtcmask[32] = {
    0xff, 0xff, 0xff, 0xff, 0x7f, 0x1f, 0x7f, 0x7f, 0xf3, 0x1f, 0x7f, 0x1f, 0x3f, 0xff, 0x3f, 0xff,
    0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};

static video_timings_t timing_cga = { .type = VIDEO_ISA, .write_b = 8, .write_w = 16, .write_l = 32, .read_b = 8, .read_w = 16, .read_l = 32 };

void cga_recalctimings(cga_t *cga);

void
cga_out(uint16_t addr, uint8_t val, void *p)
{
    cga_t  *cga = (cga_t *) p;
    uint8_t old;

    if ((addr >= 0x3d0) && (addr <= 0x3d7))
        addr = (addr & 0xff9) | 0x004;

    switch (addr) {
        case 0x3D4:
            cga->crtcreg = val & 31;
            return;
        case 0x3D5:
            old                     = cga->crtc[cga->crtcreg];
            cga->crtc[cga->crtcreg] = val & crtcmask[cga->crtcreg];
            if (old != val) {
                if ((cga->crtcreg < 0xe) || (cga->crtcreg > 0x10)) {
                    cga->fullchange = changeframecount;
                    cga_recalctimings(cga);
                }
            }
            return;
        case 0x3D8:
            old          = cga->cgamode;
            cga->cgamode = val;

            if (old ^ val) {
                if ((old ^ val) & 0x05)
                    update_cga16_color(val);

                cga_recalctimings(cga);
            }
            return;
        case 0x3D9:
            old         = cga->cgacol;
            cga->cgacol = val;
            if (old ^ val)
                cga_recalctimings(cga);
            return;
    }
}

uint8_t
cga_in(uint16_t addr, void *p)
{
    cga_t *cga = (cga_t *) p;

    uint8_t ret = 0xff;

    if ((addr >= 0x3d0) && (addr <= 0x3d7))
        addr = (addr & 0xff9) | 0x004;

    switch (addr) {
        case 0x3D4:
            ret = cga->crtcreg;
            break;
        case 0x3D5:
            ret = cga->crtc[cga->crtcreg];
            break;
        case 0x3DA:
            ret = cga->cgastat;
            break;
    }

    return ret;
}

void
cga_pravetz_out(uint16_t addr, uint8_t val, void *p)
{
    cga_t *cga = (cga_t *) p;

    cga->fontbase = (((unsigned int) val) << 8);
}

uint8_t
cga_pravetz_in(uint16_t addr, void *p)
{
    cga_t *cga = (cga_t *) p;

    return (cga->fontbase >> 8);
}

void
cga_waitstates(void *p)
{
    int ws_array[16] = { 3, 4, 5, 6, 7, 8, 4, 5, 6, 7, 8, 4, 5, 6, 7, 8 };
    int ws;

    ws = ws_array[cycles & 0xf];
    cycles -= ws;
}

void
cga_write(uint32_t addr, uint8_t val, void *p)
{
    cga_t *cga = (cga_t *) p;

    cga->vram[addr & 0x3fff] = val;
    if (cga->snow_enabled) {
        int offset                  = ((timer_get_remaining_u64(&cga->timer) / CGACONST) * 2) & 0xfc;
        cga->charbuffer[offset]     = cga->vram[addr & 0x3fff];
        cga->charbuffer[offset | 1] = cga->vram[addr & 0x3fff];
    }
    cga_waitstates(cga);
}

uint8_t
cga_read(uint32_t addr, void *p)
{
    cga_t *cga = (cga_t *) p;

    cga_waitstates(cga);
    if (cga->snow_enabled) {
        int offset                  = ((timer_get_remaining_u64(&cga->timer) / CGACONST) * 2) & 0xfc;
        cga->charbuffer[offset]     = cga->vram[addr & 0x3fff];
        cga->charbuffer[offset | 1] = cga->vram[addr & 0x3fff];
    }
    return cga->vram[addr & 0x3fff];
}

void
cga_recalctimings(cga_t *cga)
{
    double disptime;
    double _dispontime, _dispofftime;

    if (cga->cgamode & 1) {
        disptime    = (double) (cga->crtc[0] + 1);
        _dispontime = (double) cga->crtc[1];
    } else {
        disptime    = (double) ((cga->crtc[0] + 1) << 1);
        _dispontime = (double) (cga->crtc[1] << 1);
    }
    _dispofftime     = disptime - _dispontime;
    _dispontime      = _dispontime * CGACONST;
    _dispofftime     = _dispofftime * CGACONST;
    cga->dispontime  = (uint64_t) (_dispontime);
    cga->dispofftime = (uint64_t) (_dispofftime);
}

void
cga_poll(void *p)
{
    cga_t   *cga = (cga_t *) p;
    uint16_t ca  = (cga->crtc[15] | (cga->crtc[14] << 8)) & 0x3fff;
    int      drawcursor;
    int      x, c, xs_temp, ys_temp;
    int      oldvc;
    uint8_t  chr, attr;
    uint8_t  border;
    uint16_t dat;
    int      cols[4];
    int      col;
    int      oldsc;

    if (!cga->linepos) {
        timer_advance_u64(&cga->timer, cga->dispofftime);
        cga->cgastat |= 1;
        cga->linepos = 1;
        oldsc        = cga->sc;
        if ((cga->crtc[8] & 3) == 3)
            cga->sc = ((cga->sc << 1) + cga->oddeven) & 7;
        if (cga->cgadispon) {
            if (cga->displine < cga->firstline) {
                cga->firstline = cga->displine;
                video_wait_for_buffer();
            }
            cga->lastline = cga->displine;
            for (c = 0; c < 8; c++) {
                if ((cga->cgamode & 0x12) == 0x12) {
                    buffer32->line[(cga->displine << 1)][c] = buffer32->line[(cga->displine << 1) + 1][c] = 0;
                    if (cga->cgamode & 1) {
                        buffer32->line[(cga->displine << 1)][c + (cga->crtc[1] << 3) + 8] = buffer32->line[(cga->displine << 1) + 1][c + (cga->crtc[1] << 3) + 8] = 0;
                    } else {
                        buffer32->line[(cga->displine << 1)][c + (cga->crtc[1] << 4) + 8] = buffer32->line[(cga->displine << 1) + 1][c + (cga->crtc[1] << 4) + 8] = 0;
                    }
                } else {
                    buffer32->line[(cga->displine << 1)][c] = buffer32->line[(cga->displine << 1) + 1][c] = (cga->cgacol & 15) + 16;
                    if (cga->cgamode & 1) {
                        buffer32->line[(cga->displine << 1)][c + (cga->crtc[1] << 3) + 8] = buffer32->line[(cga->displine << 1) + 1][c + (cga->crtc[1] << 3) + 8] = (cga->cgacol & 15) + 16;
                    } else {
                        buffer32->line[(cga->displine << 1)][c + (cga->crtc[1] << 4) + 8] = buffer32->line[(cga->displine << 1) + 1][c + (cga->crtc[1] << 4) + 8] = (cga->cgacol & 15) + 16;
                    }
                }
            }
            if (cga->cgamode & 1) {
                for (x = 0; x < cga->crtc[1]; x++) {
                    if (cga->cgamode & 8) {
                        chr  = cga->charbuffer[x << 1];
                        attr = cga->charbuffer[(x << 1) + 1];
                    } else
                        chr = attr = 0;
                    drawcursor = ((cga->ma == ca) && cga->con && cga->cursoron);
                    cols[1]    = (attr & 15) + 16;
                    if (cga->cgamode & 0x20) {
                        cols[0] = ((attr >> 4) & 7) + 16;
                        if ((cga->cgablink & 8) && (attr & 0x80) && !cga->drawcursor)
                            cols[1] = cols[0];
                    } else
                        cols[0] = (attr >> 4) + 16;
                    if (drawcursor) {
                        for (c = 0; c < 8; c++) {
                            buffer32->line[(cga->displine << 1)][(x << 3) + c + 8] = buffer32->line[(cga->displine << 1) + 1][(x << 3) + c + 8] = cols[(fontdat[chr + cga->fontbase][cga->sc & 7] & (1 << (c ^ 7))) ? 1 : 0] ^ 15;
                        }
                    } else {
                        for (c = 0; c < 8; c++) {
                            buffer32->line[(cga->displine << 1)][(x << 3) + c + 8] = buffer32->line[(cga->displine << 1) + 1][(x << 3) + c + 8] = cols[(fontdat[chr + cga->fontbase][cga->sc & 7] & (1 << (c ^ 7))) ? 1 : 0];
                        }
                    }
                    cga->ma++;
                }
            } else if (!(cga->cgamode & 2)) {
                for (x = 0; x < cga->crtc[1]; x++) {
                    if (cga->cgamode & 8) {
                        chr  = cga->vram[((cga->ma << 1) & 0x3fff)];
                        attr = cga->vram[(((cga->ma << 1) + 1) & 0x3fff)];
                    } else
                        chr = attr = 0;
                    drawcursor = ((cga->ma == ca) && cga->con && cga->cursoron);
                    cols[1]    = (attr & 15) + 16;
                    if (cga->cgamode & 0x20) {
                        cols[0] = ((attr >> 4) & 7) + 16;
                        if ((cga->cgablink & 8) && (attr & 0x80))
                            cols[1] = cols[0];
                    } else
                        cols[0] = (attr >> 4) + 16;
                    cga->ma++;
                    if (drawcursor) {
                        for (c = 0; c < 8; c++) {
                            buffer32->line[(cga->displine << 1)][(x << 4) + (c << 1) + 8] = buffer32->line[(cga->displine << 1)][(x << 4) + (c << 1) + 1 + 8] = buffer32->line[(cga->displine << 1) + 1][(x << 4) + (c << 1) + 8] = buffer32->line[(cga->displine << 1) + 1][(x << 4) + (c << 1) + 1 + 8] = cols[(fontdat[chr + cga->fontbase][cga->sc & 7] & (1 << (c ^ 7))) ? 1 : 0] ^ 15;
                        }
                    } else {
                        for (c = 0; c < 8; c++) {
                            buffer32->line[(cga->displine << 1)][(x << 4) + (c << 1) + 8] = buffer32->line[(cga->displine << 1)][(x << 4) + (c << 1) + 1 + 8] = buffer32->line[(cga->displine << 1) + 1][(x << 4) + (c << 1) + 8] = buffer32->line[(cga->displine << 1) + 1][(x << 4) + (c << 1) + 1 + 8] = cols[(fontdat[chr + cga->fontbase][cga->sc & 7] & (1 << (c ^ 7))) ? 1 : 0];
                        }
                    }
                }
            } else if (!(cga->cgamode & 16)) {
                cols[0] = (cga->cgacol & 15) | 16;
                col     = (cga->cgacol & 16) ? 24 : 16;
                if (cga->cgamode & 4) {
                    cols[1] = col | 3; /* Cyan */
                    cols[2] = col | 4; /* Red */
                    cols[3] = col | 7; /* White */
                } else if (cga->cgacol & 32) {
                    cols[1] = col | 3; /* Cyan */
                    cols[2] = col | 5; /* Magenta */
                    cols[3] = col | 7; /* White */
                } else {
                    cols[1] = col | 2; /* Green */
                    cols[2] = col | 4; /* Red */
                    cols[3] = col | 6; /* Yellow */
                }
                for (x = 0; x < cga->crtc[1]; x++) {
                    if (cga->cgamode & 8)
                        dat = (cga->vram[((cga->ma << 1) & 0x1fff) + ((cga->sc & 1) * 0x2000)] << 8) | cga->vram[((cga->ma << 1) & 0x1fff) + ((cga->sc & 1) * 0x2000) + 1];
                    else
                        dat = 0;
                    cga->ma++;
                    for (c = 0; c < 8; c++) {
                        buffer32->line[(cga->displine << 1)][(x << 4) + (c << 1) + 8] = buffer32->line[(cga->displine << 1)][(x << 4) + (c << 1) + 1 + 8] = buffer32->line[(cga->displine << 1) + 1][(x << 4) + (c << 1) + 8] = buffer32->line[(cga->displine << 1) + 1][(x << 4) + (c << 1) + 1 + 8] = cols[dat >> 14];
                        dat <<= 2;
                    }
                }
            } else {
                cols[0] = 0;
                cols[1] = (cga->cgacol & 15) + 16;
                for (x = 0; x < cga->crtc[1]; x++) {
                    if (cga->cgamode & 8)
                        dat = (cga->vram[((cga->ma << 1) & 0x1fff) + ((cga->sc & 1) * 0x2000)] << 8) | cga->vram[((cga->ma << 1) & 0x1fff) + ((cga->sc & 1) * 0x2000) + 1];
                    else
                        dat = 0;
                    cga->ma++;
                    for (c = 0; c < 16; c++) {
                        buffer32->line[(cga->displine << 1)][(x << 4) + c + 8] = buffer32->line[(cga->displine << 1) + 1][(x << 4) + c + 8] = cols[dat >> 15];
                        dat <<= 1;
                    }
                }
            }
        } else {
            cols[0] = ((cga->cgamode & 0x12) == 0x12) ? 0 : (cga->cgacol & 15) + 16;
            if (cga->cgamode & 1) {
                hline(buffer32, 0, (cga->displine << 1), ((cga->crtc[1] << 3) + 16) << 2, cols[0]);
                hline(buffer32, 0, (cga->displine << 1) + 1, ((cga->crtc[1] << 3) + 16) << 2, cols[0]);
            } else {
                hline(buffer32, 0, (cga->displine << 1), ((cga->crtc[1] << 4) + 16) << 2, cols[0]);
                hline(buffer32, 0, (cga->displine << 1) + 1, ((cga->crtc[1] << 4) + 16) << 2, cols[0]);
            }
        }

        if (cga->cgamode & 1)
            x = (cga->crtc[1] << 3) + 16;
        else
            x = (cga->crtc[1] << 4) + 16;

        if (cga->composite) {
            if (cga->cgamode & 0x10)
                border = 0x00;
            else
                border = cga->cgacol & 0x0f;

            Composite_Process(cga->cgamode, border, x >> 2, buffer32->line[(cga->displine << 1)]);
            Composite_Process(cga->cgamode, border, x >> 2, buffer32->line[(cga->displine << 1) + 1]);
        } else {
            video_process_8(x, cga->displine << 1);
            video_process_8(x, (cga->displine << 1) + 1);
        }

        cga->sc = oldsc;
        if (cga->vc == cga->crtc[7] && !cga->sc)
            cga->cgastat |= 8;
        cga->displine++;
        if (cga->displine >= 360)
            cga->displine = 0;
    } else {
        timer_advance_u64(&cga->timer, cga->dispontime);
        cga->linepos = 0;
        if (cga->vsynctime) {
            cga->vsynctime--;
            if (!cga->vsynctime)
                cga->cgastat &= ~8;
        }
        if (cga->sc == (cga->crtc[11] & 31) || ((cga->crtc[8] & 3) == 3 && cga->sc == ((cga->crtc[11] & 31) >> 1))) {
            cga->con  = 0;
            cga->coff = 1;
        }
        if ((cga->crtc[8] & 3) == 3 && cga->sc == (cga->crtc[9] >> 1))
            cga->maback = cga->ma;
        if (cga->vadj) {
            cga->sc++;
            cga->sc &= 31;
            cga->ma = cga->maback;
            cga->vadj--;
            if (!cga->vadj) {
                cga->cgadispon = 1;
                cga->ma = cga->maback = (cga->crtc[13] | (cga->crtc[12] << 8)) & 0x3fff;
                cga->sc               = 0;
            }
        } else if (cga->sc == cga->crtc[9]) {
            cga->maback = cga->ma;
            cga->sc     = 0;
            oldvc       = cga->vc;
            cga->vc++;
            cga->vc &= 127;

            if (cga->vc == cga->crtc[6])
                cga->cgadispon = 0;

            if (oldvc == cga->crtc[4]) {
                cga->vc   = 0;
                cga->vadj = cga->crtc[5];
                if (!cga->vadj) {
                    cga->cgadispon = 1;
                    cga->ma = cga->maback = (cga->crtc[13] | (cga->crtc[12] << 8)) & 0x3fff;
                }
                switch (cga->crtc[10] & 0x60) {
                    case 0x20:
                        cga->cursoron = 0;
                        break;
                    case 0x60:
                        cga->cursoron = cga->cgablink & 0x10;
                        break;
                    default:
                        cga->cursoron = cga->cgablink & 0x08;
                        break;
                }
            }

            if (cga->vc == cga->crtc[7]) {
                cga->cgadispon = 0;
                cga->displine  = 0;
                cga->vsynctime = 16;
                if (cga->crtc[7]) {
                    if (cga->cgamode & 1)
                        x = (cga->crtc[1] << 3) + 16;
                    else
                        x = (cga->crtc[1] << 4) + 16;
                    cga->lastline++;

                    xs_temp = x;
                    ys_temp = (cga->lastline - cga->firstline) << 1;

                    if ((xs_temp > 0) && (ys_temp > 0)) {
                        if (xs_temp < 64)
                            xs_temp = 656;
                        if (ys_temp < 32)
                            ys_temp = 400;
                        if (!enable_overscan)
                            xs_temp -= 16;

                        if ((cga->cgamode & 8) && ((xs_temp != xsize) || (ys_temp != ysize) || video_force_resize_get())) {
                            xsize = xs_temp;
                            ysize = ys_temp;
                            set_screen_size(xsize, ysize + (enable_overscan ? 16 : 0));

                            if (video_force_resize_get())
                                video_force_resize_set(0);
                        }

                        if (enable_overscan) {
                            video_blit_memtoscreen(0, (cga->firstline - 4) << 1,
                                                   xsize, ((cga->lastline - cga->firstline) + 8) << 1);
                        } else {
                            video_blit_memtoscreen(8, cga->firstline << 1,
                                                   xsize, (cga->lastline - cga->firstline) << 1);
                        }
                    }

                    frames++;

                    video_res_x = xsize;
                    video_res_y = ysize;
                    if (cga->cgamode & 1) {
                        video_res_x /= 8;
                        video_res_y /= cga->crtc[9] + 1;
                        video_bpp = 0;
                    } else if (!(cga->cgamode & 2)) {
                        video_res_x /= 16;
                        video_res_y /= cga->crtc[9] + 1;
                        video_bpp = 0;
                    } else if (!(cga->cgamode & 16)) {
                        video_res_x /= 2;
                        video_bpp = 2;
                    } else
                        video_bpp = 1;
                }
                cga->firstline = 1000;
                cga->lastline  = 0;
                cga->cgablink++;
                cga->oddeven ^= 1;
            }
        } else {
            cga->sc++;
            cga->sc &= 31;
            cga->ma = cga->maback;
        }
        if (cga->cgadispon)
            cga->cgastat &= ~1;
        if ((cga->sc == (cga->crtc[10] & 31) || ((cga->crtc[8] & 3) == 3 && cga->sc == ((cga->crtc[10] & 31) >> 1))))
            cga->con = 1;
        if (cga->cgadispon && (cga->cgamode & 1)) {
            for (x = 0; x < (cga->crtc[1] << 1); x++)
                cga->charbuffer[x] = cga->vram[(((cga->ma << 1) + x) & 0x3fff)];
        }
    }
}

void
cga_init(cga_t *cga)
{
    timer_add(&cga->timer, cga_poll, cga, 1);
    cga->composite = 0;
}

void *
cga_standalone_init(const device_t *info)
{
    int    display_type;
    cga_t *cga = malloc(sizeof(cga_t));

    memset(cga, 0, sizeof(cga_t));
    video_inform(VIDEO_FLAG_TYPE_CGA, &timing_cga);

    display_type      = device_get_config_int("display_type");
    cga->composite    = (display_type != CGA_RGB);
    cga->revision     = device_get_config_int("composite_type");
    cga->snow_enabled = device_get_config_int("snow_enabled");

    cga->vram = malloc(0x4000);

    cga_comp_init(cga->revision);
    timer_add(&cga->timer, cga_poll, cga, 1);
    mem_mapping_add(&cga->mapping, 0xb8000, 0x08000, cga_read, NULL, NULL, cga_write, NULL, NULL, NULL /*cga->vram*/, MEM_MAPPING_EXTERNAL, cga);
    io_sethandler(0x03d0, 0x0010, cga_in, NULL, NULL, cga_out, NULL, NULL, cga);

    overscan_x = overscan_y = 16;

    cga->rgb_type = device_get_config_int("rgb_type");
    cga_palette   = (cga->rgb_type << 1);
    cgapal_rebuild();

    return cga;
}

void *
cga_pravetz_init(const device_t *info)
{
    cga_t *cga = cga_standalone_init(info);

    loadfont("roms/video/cga/PRAVETZ-VDC2.BIN", 10);

    io_removehandler(0x03dd, 0x0001, cga_in, NULL, NULL, cga_out, NULL, NULL, cga);
    io_sethandler(0x03dd, 0x0001, cga_pravetz_in, NULL, NULL, cga_pravetz_out, NULL, NULL, cga);

    cga->fontbase = 0x0300;

    return cga;
}

void
cga_close(void *p)
{
    cga_t *cga = (cga_t *) p;

    free(cga->vram);
    free(cga);
}

void
cga_speed_changed(void *p)
{
    cga_t *cga = (cga_t *) p;

    cga_recalctimings(cga);
}

// clang-format off
const device_config_t cga_config[] = {
    {
        .name = "display_type",
        .description = "Display type",
        .type = CONFIG_SELECTION,
        .default_int = CGA_RGB,
        .selection = {
            {
                .description = "RGB",
                .value = CGA_RGB
            },
            {
                .description = "Composite",
                .value = CGA_COMPOSITE
            },
            {
                .description = ""
            }
        }
    },
    {
        .name = "composite_type",
        .description = "Composite type",
        .type = CONFIG_SELECTION,
        .default_int = COMPOSITE_OLD,
        .selection = {
            {
                .description = "Old",
                .value = COMPOSITE_OLD
            },
            {
                .description = "New",
                .value = COMPOSITE_NEW
            },
            {
                .description = ""
            }
        }
    },
    {
        .name = "rgb_type",
        .description = "RGB type",
        .type = CONFIG_SELECTION,
        .default_int = 0,
        .selection = {
            {
                .description = "Color",
                .value = 0
            },
            {
                .description = "Green Monochrome",
                .value = 1
            },
            {
                .description = "Amber Monochrome",
                .value = 2
            },
            {
                .description = "Gray Monochrome",
                .value = 3
            },
            {
                .description = "Color (no brown)",
                .value = 4
            },
            {
                .description = ""
            }
        }
    },
    {
        .name = "snow_enabled",
        .description = "Snow emulation",
        .type = CONFIG_BINARY,
        .default_int = 1
    },
    {
        .type = CONFIG_END
    }
};
// clang-format on

const device_t cga_device = {
    .name          = "CGA",
    .internal_name = "cga",
    .flags         = DEVICE_ISA,
    .local         = 0,
    .init          = cga_standalone_init,
    .close         = cga_close,
    .reset         = NULL,
    { .available = NULL },
    .speed_changed = cga_speed_changed,
    .force_redraw  = NULL,
    .config        = cga_config
};

const device_t cga_pravetz_device = {
    .name          = "Pravetz VDC-2",
    .internal_name = "cga_pravetz",
    .flags         = DEVICE_ISA,
    .local         = 0,
    .init          = cga_pravetz_init,
    .close         = cga_close,
    .reset         = NULL,
    { .available = NULL },
    .speed_changed = cga_speed_changed,
    .force_redraw  = NULL,
    .config        = cga_config
};