ACCESS.bus

Co-Authored-By: Miran Grča <oubattler@gmail.com>

src/device/CMakeLists.txt

@@ -17,6 +17,7 @@
 #
 
 add_library(dev OBJECT
+    access_bus.c
     bugger.c
     cartridge.c
     cassette.c

src/device/access_bus.c

@@ -0,0 +1,122 @@
+/*
+ * 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.
+ *
+ *          Implementation of the ACCESS.bus.
+ *
+ * Authors: Miran Grca, <mgrca8@gmail.com>
+ *
+ *          Copyright 2024-2025 Miran Grca.
+ */
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <wchar.h>
+#include <86box/86box.h>
+#include <86box/io.h>
+#include <86box/device.h>
+#include <86box/access_bus.h>
+#include <86box/plat_unused.h>
+
+static uint8_t
+access_bus_in(uint16_t port, void *priv)
+{
+    const access_bus_t *dev = (access_bus_t *) priv;
+    uint8_t             ret = 0xff;
+
+    switch (port & 3) {
+        case 0:
+            ret = (dev->status & 0xbf);
+            break;
+        case 1:
+            ret = (dev->own_addr & 0x7f);
+            break;
+        case 2:
+            ret = dev->data;
+            break;
+        case 3:
+            ret = (dev->clock & 0x87);
+            break;
+
+        default:
+            break;
+    }
+
+    return ret;
+}
+
+static void
+access_bus_out(uint16_t port, uint8_t val, void *priv)
+{
+    access_bus_t *dev = (access_bus_t *) priv;
+
+    switch (port & 3) {
+        case 0:
+            dev->control = (val & 0xcf);
+            break;
+        case 1:
+            dev->own_addr = (val & 0x7f);
+            break;
+        case 2:
+            dev->data = val;
+            break;
+        case 3:
+            dev->clock &= 0x80;
+            dev->clock |= (val & 0x07);
+            break;
+
+        default:
+            break;
+    }
+}
+
+void
+access_bus_handler(access_bus_t *dev, uint8_t enable, uint16_t base)
+{
+    if (dev->enable && (dev->base >= 0x0100) && (dev->base <= 0x0ffc))
+        io_removehandler(dev->base, 0x0004,
+                         access_bus_in, NULL, NULL, access_bus_out, NULL, NULL, dev);
+
+    dev->enable = enable;
+    dev->base   = base;
+
+    if (dev->enable && (dev->base >= 0x0100) && (dev->base <= 0x0ffc))
+        io_sethandler(dev->base, 0x0004,
+                      access_bus_in, NULL, NULL, access_bus_out, NULL, NULL, dev);
+}
+
+
+static void
+access_bus_close(void *priv)
+{
+    access_bus_t *dev = (access_bus_t *) priv;
+
+    free(dev);
+}
+
+static void *
+access_bus_init(UNUSED(const device_t *info))
+{
+    access_bus_t *dev = (access_bus_t *) calloc(1, sizeof(access_bus_t));
+
+    return dev;
+}
+
+const device_t access_bus_device = {
+    .name          = "ACCESS.bus",
+    .internal_name = "access_bus",
+    .flags         = 0,
+    .local         = 0,
+    .init          = access_bus_init,
+    .close         = access_bus_close,
+    .reset         = NULL,
+    .available     = NULL,
+    .speed_changed = NULL,
+    .force_redraw  = NULL,
+    .config        = NULL
+};