implement autoinstallation to upper memory

1 files changed, 100 insertions, 0 deletions

diff --git a/int21dos.h b/int21dos.h
new file mode 100644
index 0000000..3990793
--- /dev/null
+++ b/int21dos.h
@@ -0,0 +1,100 @@
+/*
+ * VBMouse - Interface to some DOS int 21h services
+ * Copyright (C) 2022 Javier S. Pedro
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+#ifndef INT21DOS_H
+#define INT21DOS_H
+
+#include <stdbool.h>
+#include <dos.h>
+
+#define DOS_PSP_SIZE 256
+
+enum dos_allocation_strategy {
+	DOS_FIT_FIRST    = 0,
+	DOS_FIT_BEST     = 1,
+	DOS_FIT_LAST     = 2,
+
+	DOS_FIT_HIGH     = 0x80,
+	DOS_FIT_HIGHONLY = 0x40,
+};
+
+static unsigned dos_query_allocation_strategy(void);
+#pragma aux dos_query_allocation_strategy = \
+	"mov ax, 0x5800" \
+	"int 0x21" \
+	__value [ax]
+
+static int dos_set_allocation_strategy(unsigned strategy);
+#pragma aux dos_set_allocation_strategy = \
+	"clc" \
+	"mov ax, 0x5801" \
+	"int 0x21" \
+	"jc end" \
+	"mov ax, 0" \
+	"end:" \
+	__parm [bx] \
+	__value [ax]
+
+static bool dos_query_umb_link_state(void);
+#pragma aux dos_query_umb_link_state = \
+	"mov ax, 0x5802" \
+	"int 0x21" \
+	__value [al]
+
+static int dos_set_umb_link_state(bool state);
+#pragma aux dos_set_umb_link_state = \
+	"clc" \
+	"mov ax, 0x5803" \
+	"int 0x21" \
+	"jc end" \
+	"mov ax, 0" \
+	"end:" \
+	__parm [bx] \
+	__value [ax]
+
+/** Allocates a new DOS segment.
+ *  @returns either the allocated segment or 0 if any error. */
+static __segment dos_alloc(unsigned paragraphs);
+#pragma aux dos_alloc = \
+	"clc" \
+	"mov ah, 0x48" \
+	"int 0x21" \
+	"jnc end" \
+	"mov ax, 0xB" \
+	"end:" \
+	__parm [bx] \
+	__value [ax]
+
+/** Frees DOS segment. */
+static void dos_free(_segment segment);
+#pragma aux dos_free = \
+	"mov ah, 0x49" \
+	"int 0x21" \
+	__parm [es] \
+	__modify [ax]
+
+/** Sets a given PSP as the current active process. */
+static void dos_set_psp(_segment psp);
+#pragma aux dos_set_psp = \
+	"mov ah, 0x50" \
+	"int 0x21" \
+	__parm [bx] \
+	__modify [ax]
+
+#endif // INT21DOS_H