86Box/src/video/vid_sc1502x_ramdac.c

/*
 * 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 a Sierra SC1502X RAMDAC.
 *
 *          Used by the TLIVESA1 driver for ET4000.
 *
 *
 *
 * Authors: Sarah Walker, <https://pcem-emulator.co.uk/>
 *          Miran Grca, <mgrca8@gmail.com>
 *
 *          Copyright 2008-2018 Sarah Walker.
 *          Copyright 2016-2018 Miran Grca.
 */
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <wchar.h>
#include <86box/86box.h>
#include <86box/device.h>
#include <86box/mem.h>
#include <86box/timer.h>
#include <86box/video.h>
#include <86box/vid_svga.h>
#include <86box/plat_unused.h>

typedef struct sc1502x_ramdac_t {
    int     state;
    uint8_t ctrl;
} sc1502x_ramdac_t;

void
sc1502x_ramdac_out(uint16_t addr, uint8_t val, void *priv, svga_t *svga)
{
    sc1502x_ramdac_t *ramdac = (sc1502x_ramdac_t *) priv;
    int               oldbpp = 0;

    switch (addr) {
        case 0x3C6:
            if (ramdac->state == 4) {
                ramdac->state = 0;
                if (val == 0xFF)
                    break;
                ramdac->ctrl = val;
                oldbpp       = svga->bpp;
                switch ((val & 1) | ((val & 0xc0) >> 5)) {
                    case 0:
                        svga->bpp = 8;
                        break;
                    case 2:
                    case 3:
                        switch (val & 0x20) {
                            case 0x00:
                                svga->bpp = 32;
                                break;
                            case 0x20:
                                svga->bpp = 24;
                                break;

                            default:
                                break;
                        }
                        break;
                    case 4:
                    case 5:
                        svga->bpp = 15;
                        break;
                    case 6:
                        svga->bpp = 16;
                        break;
                    case 7:
                        if (val & 4) {
                            switch (val & 0x20) {
                                case 0x00:
                                    svga->bpp = 32;
                                    break;
                                case 0x20:
                                    svga->bpp = 24;
                                    break;

                                default:
                                    break;
                            }
                        } else {
                            svga->bpp = 16;
                        }
                        break;

                    default:
                        break;
                }
                if (oldbpp != svga->bpp)
                    svga_recalctimings(svga);
                return;
            }
            ramdac->state = 0;
            break;
        case 0x3C7:
        case 0x3C8:
        case 0x3C9:
            ramdac->state = 0;
            break;

        default:
            break;
    }

    svga_out(addr, val, svga);
}

uint8_t
sc1502x_ramdac_in(uint16_t addr, void *p, svga_t *svga)
{
    sc1502x_ramdac_t *ramdac = (sc1502x_ramdac_t *) p;
    uint8_t           temp   = svga_in(addr, svga);

    switch (addr) {
        case 0x3C6:
            if (ramdac->state == 4) {
                ramdac->state = 0;
                temp          = ramdac->ctrl;
                break;
            }
            ramdac->state++;
            break;
        case 0x3C7:
        case 0x3C8:
        case 0x3C9:
            ramdac->state = 0;
            break;

        default:
            break;
    }

    return temp;
}

static void *
sc1502x_ramdac_init(UNUSED(const device_t *info))
{
    sc1502x_ramdac_t *ramdac = (sc1502x_ramdac_t *) malloc(sizeof(sc1502x_ramdac_t));
    memset(ramdac, 0, sizeof(sc1502x_ramdac_t));

    return ramdac;
}

static void
sc1502x_ramdac_close(void *priv)
{
    sc1502x_ramdac_t *ramdac = (sc1502x_ramdac_t *) priv;

    if (ramdac)
        free(ramdac);
}

const device_t sc1502x_ramdac_device = {
    .name          = "Sierra SC1502x RAMDAC",
    .internal_name = "sc1502x_ramdac",
    .flags         = 0,
    .local         = 0,
    .init          = sc1502x_ramdac_init,
    .close         = sc1502x_ramdac_close,
    .reset         = NULL,
    { .available = NULL },
    .speed_changed = NULL,
    .force_redraw  = NULL,
    .config        = NULL
};