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diff --git a/sos-code-article6.5/hwcore/segment.h b/sos-code-article6.5/hwcore/segment.h
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+/* Copyright (C) 2004  The SOS Team
+
+   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_HWSEGS_H_
+#define _SOS_HWSEGS_H_
+
+/**
+ * @file segments.h
+ *
+ * Global and local (GDT/LDT) segment descriptor definition and
+ * structure. These segments map virtual addresses (ie
+ * data/instruction addresses, relative to these segment descriptors)
+ * to linear addresses (ie addresses in the paged-memory space).
+ *
+ * @see Intel x86 doc, vol 3 chapter 3.
+ */
+
+
+/*
+ * Global segment selectors (GDT) for SOS/x86.
+ *
+ * @see gdt.h
+ */
+#define SOS_SEG_NULL       0 /* NULL segment, unused by the procesor */
+#define SOS_SEG_KCODE      1 /* Kernel code segment */
+#define SOS_SEG_KDATA      2 /* Kernel data segment */
+
+
+#ifndef ASM_SOURCE
+/**
+ * Helper macro that builds a segment register's value
+ */
+#define SOS_BUILD_SEGMENT_REG_VALUE(desc_privilege,in_ldt,seg_index) \
+  (  (((desc_privilege) & 0x3)  << 0) \
+   | (((in_ldt)?1:0)            << 2) \
+   | ((seg_index)               << 3) )
+#else
+/*
+ * Assembler-compliant version.
+ *
+ * Caution: In assembler code, "in_ldt" MUST be either 1 or 0, nothing
+ * else.
+ */
+#define SOS_BUILD_SEGMENT_REG_VALUE(desc_privilege,in_ldt,seg_index) \
+  (  (((desc_privilege) & 0x3)  << 0) \
+   | ((in_ldt & 1)              << 2) \
+   | ((seg_index)               << 3) )
+#endif
+
+
+/*
+ * Local segment selectors (LDT) for SOS/x86
+ */
+/* None */
+
+#endif /* _SOS_HWSEGS_H_ */