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+/* Copyright (C) 2004  David Decotigny
+
+   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., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+   USA. 
+*/
+#ifndef _SOS_IDT_H_
+#define _SOS_IDT_H_
+
+/**
+ * @file idt.h
+ *
+ * Manage the x86 Interrupt Descriptor Table, the table which maps the
+ * hardware interrupt lines, hardware exceptions, and software
+ * interrupts, to software routines. We only define "interrupt gate"
+ * IDT entries. Don't use it directly; refer instead to interrupt.c,
+ * exceptions.c and syscall.c.
+ *
+ * @see Intel x86 doc, Vol 3, chapter 5
+ */
+
+#include <sos/errno.h>
+#include <sos/types.h>
+
+/* Mapping of the CPU exceptions in the IDT (imposed by Intel
+   standards) */
+#define SOS_EXCEPT_BASE 0
+#define SOS_EXCEPT_NUM  32
+#define SOS_EXCEPT_MAX  (SOS_HWEXCEPT_BASE + SOS_HWEXCEPT_NUM - 1)
+
+/* Mapping of the IRQ lines in the IDT */
+#define SOS_IRQ_BASE    32
+#define SOS_IRQ_NUM     16
+#define SOS_IRQ_MAX     (SOS_IRQ_BASE + SOS_IRQ_NUM - 1)
+
+/**
+ * Number of IDT entries.
+ *
+ * @note Must be large enough to map the hw interrupts, the exceptions
+ * (=> total is 48 entries), and the syscall(s). Since our syscall
+ * will be 0x42, it must be >= 0x43. Intel doc limits this to 256
+ * entries, we use this limit.
+ */
+#define SOS_IDTE_NUM      256 /* 0x100 */
+
+/** Initialization routine: all the IDT entries (or "IDTE") are marked
+    "not present". */
+sos_ret_t sos_idt_subsystem_setup(void);
+
+/**
+ * Enable the IDT entry if handler_address != NULL, with the given
+ * lowest_priviledge.\ Disable the IDT entry when handler_address ==
+ * NULL (the lowest_priviledge parameter is then ignored). Intel doc
+ * says that there must not be more than 256 entries.
+ *
+ * @note IRQ Unsafe
+ */
+sos_ret_t sos_idt_set_handler(int index,
+			      sos_vaddr_t handler_address,
+			      int lowest_priviledge /* 0..3 */);
+
+
+/**
+ * @note IRQ Unsafe
+ *
+ * @return the handler address and DPL in the 2nd and 3rd
+ * parameters
+ */
+sos_ret_t sos_idt_get_handler(int index,
+			      sos_vaddr_t *handler_address,
+			      int *lowest_priviledge);
+
+#endif /* _SOS_IDT_H_ */