132 lines
3.3 KiB
C
132 lines
3.3 KiB
C
#include <stdarg.h>
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#include <stdint.h>
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#include <stdio.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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#define HAVE_STDARG_H
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#include <86box/86box.h>
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#include "cpu.h"
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#include <86box/io.h>
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#include <86box/device.h>
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#include <86box/mem.h>
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#include <86box/plat_unused.h>
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#include <86box/chipset.h>
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typedef struct isa486c_t {
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uint8_t regs[3];
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} isa486c_t;
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static void
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isa486c_recalcmapping(isa486c_t *dev)
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{
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uint32_t shflags = 0;
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uint32_t bases[5] = { 0x000c0000, 0x000c8000, 0x000d0000, 0x000d8000, 0x000e0000 };
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uint32_t sizes[5] = { 0x00008000, 0x00008000, 0x00008000, 0x00008000, 0x00020000 };
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if (dev->regs[1] & 0x20)
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shflags = MEM_READ_EXTANY | MEM_WRITE_INTERNAL;
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else
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shflags = MEM_READ_INTERNAL | MEM_WRITE_EXTANY;
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shadowbios = 0;
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shadowbios_write = 0;
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for (uint8_t i = 0; i < 5; i++)
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if (dev->regs[1] & (1 << i)) {
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if (i == 4) {
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shadowbios = 1;
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shadowbios_write = !!(dev->regs[1] & 0x20);
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}
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mem_set_mem_state_both(bases[i], sizes[i], shflags);
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} else
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mem_set_mem_state_both(bases[i], sizes[i], MEM_READ_EXTANY | MEM_WRITE_EXTANY);
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flushmmucache_nopc();
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}
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static void
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isa486c_write(uint16_t addr, uint8_t val, void *priv)
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{
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isa486c_t *dev = (isa486c_t *) priv;
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switch (addr) {
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case 0x0023:
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dev->regs[0] = val;
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break;
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/*
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Port 25h:
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- Bit 0 = Video BIOS (C000-C7FF) shadow enabled;
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- Bit 1 = C800-C8FF shadow enabled;
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- Bit 2 = D000-D7FF shadow enabled;
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- Bit 3 = D800-DFFF shadow enabled;
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- Bit 4 = E000-FFFF shadow enabled (or F0000-FFFFF?);
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- Bit 5 = If set, read from ROM, write to shadow;
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- Bit 6 = KEN Video & BIOS enabled (cacheability!).
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*/
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case 0x0025:
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dev->regs[1] = val;
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isa486c_recalcmapping(dev);
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break;
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case 0x0027:
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dev->regs[2] = val;
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break;
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}
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}
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static uint8_t
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isa486c_read(uint16_t addr, void *priv)
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{
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isa486c_t *dev = (isa486c_t *) priv;
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uint8_t ret = 0xff;
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switch (addr) {
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case 0x0023:
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ret = dev->regs[0];
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break;
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case 0x0025:
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ret = dev->regs[1];
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break;
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case 0x0027:
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ret = dev->regs[2];
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break;
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}
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return ret;
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}
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static void
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isa486c_close(void *priv)
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{
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isa486c_t *dev = (isa486c_t *) priv;
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free(dev);
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}
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static void *
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isa486c_init(UNUSED(const device_t *info))
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{
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isa486c_t *dev = (isa486c_t *) calloc(1, sizeof(isa486c_t));
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io_sethandler(0x0023, 0x0001, isa486c_read, NULL, NULL, isa486c_write, NULL, NULL, dev);
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io_sethandler(0x0025, 0x0001, isa486c_read, NULL, NULL, isa486c_write, NULL, NULL, dev);
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io_sethandler(0x0027, 0x0001, isa486c_read, NULL, NULL, isa486c_write, NULL, NULL, dev);
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return dev;
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}
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const device_t isa486c_device = {
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.name = "ASUS ISA-486C Gate Array",
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.internal_name = "isa486c",
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.flags = 0,
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.local = 0,
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.init = isa486c_init,
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.close = isa486c_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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