162 lines
3.9 KiB
C
162 lines
3.9 KiB
C
/*
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* 86Box A hypervisor and IBM PC system emulator that specializes in
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* running old operating systems and software designed for IBM
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* PC systems and compatibles from 1981 through fairly recent
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* system designs based on the PCI bus.
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*
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* This file is part of the 86Box distribution.
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*
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* Emulation of the Brooktree BT481 true colour RAMDAC
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* family.
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*
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*
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*
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* Authors: TheCollector1995.
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*
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* Copyright 2024 TheCollector1995.
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*/
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#include <stdio.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include <wchar.h>
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#include <86box/86box.h>
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#include <86box/device.h>
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#include <86box/mem.h>
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#include <86box/timer.h>
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#include <86box/video.h>
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#include <86box/vid_svga.h>
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#include <86box/plat_unused.h>
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typedef struct bt481_ramdac_t {
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int state;
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uint8_t cmd;
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} bt481_ramdac_t;
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static void
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bt481_ramdac_command(uint8_t val, void *priv, svga_t *svga)
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{
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bt481_ramdac_t *ramdac = (bt481_ramdac_t *) priv;
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ramdac->cmd = val;
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pclog("RAMDAC CMD=%02x.\n", val);
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switch ((ramdac->cmd >> 4) & 0x0f) {
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default:
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case 0x00:
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svga->bpp = 8;
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break;
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case 0x08:
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case 0x0a:
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svga->bpp = 15;
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break;
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case 0x09:
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case 0x0c:
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svga->bpp = 16;
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break;
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case 0x0e:
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case 0x0f:
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svga->bpp = 24;
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break;
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}
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svga_recalctimings(svga);
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}
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void
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bt481_ramdac_out(uint16_t addr, int rs2, uint8_t val, void *priv, svga_t *svga)
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{
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bt481_ramdac_t *ramdac = (bt481_ramdac_t *) priv;
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uint8_t rs = (addr & 0x03) | ((!!rs2) << 2);
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switch (rs) {
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case 0x00:
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case 0x01:
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case 0x03:
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case 0x04:
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case 0x05:
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case 0x07:
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svga_out(addr, val, svga);
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ramdac->state = 0;
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break;
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case 0x02:
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pclog("RAMDAC Write State=%x.\n", ramdac->state);
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switch (ramdac->state) {
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case 4:
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bt481_ramdac_command(val, ramdac, svga);
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break;
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default:
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svga_out(addr, val, svga);
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break;
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}
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break;
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case 0x06:
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bt481_ramdac_command(val, ramdac, svga);
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ramdac->state = 0;
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break;
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default:
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break;
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}
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}
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uint8_t
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bt481_ramdac_in(uint16_t addr, int rs2, void *priv, svga_t *svga)
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{
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bt481_ramdac_t * ramdac = (bt481_ramdac_t *) priv;
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uint8_t temp = 0xff;
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uint8_t rs = (addr & 0x03) | ((!!rs2) << 2);
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switch (rs) {
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case 0x02:
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case 0x06:
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switch (ramdac->state) {
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case 4:
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temp = ramdac->cmd;
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break;
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default:
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temp = svga_in(addr, svga);
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ramdac->state++;
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break;
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}
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break;
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default:
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temp = svga_in(addr, svga);
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ramdac->state = 0;
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break;
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}
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pclog("RAMDAC IN=%02x, ret=%02x.\n", rs, temp);
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return temp;
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}
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static void *
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bt481_ramdac_init(UNUSED(const device_t *info))
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{
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bt481_ramdac_t *ramdac = (bt481_ramdac_t *) malloc(sizeof(bt481_ramdac_t));
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memset(ramdac, 0, sizeof(bt481_ramdac_t));
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return ramdac;
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}
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static void
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bt481_ramdac_close(void *priv)
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{
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bt481_ramdac_t *ramdac = (bt481_ramdac_t *) priv;
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if (ramdac)
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free(ramdac);
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}
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const device_t bt481_ramdac_device = {
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.name = "Brooktree Bt481 RAMDAC",
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.internal_name = "bt481_ramdac",
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.flags = 0,
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.local = 0,
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.init = bt481_ramdac_init,
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.close = bt481_ramdac_close,
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.reset = NULL,
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.available = NULL,
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.speed_changed = NULL,
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.force_redraw = NULL,
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.config = NULL
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};
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