From f076a3eeb9a0185b06a2abbba8c798a7761b2bdf Mon Sep 17 00:00:00 2001
From: Kevin O'Connor <kevin@koconnor.net>
Date: Mon, 25 Feb 2008 22:25:15 -0500
Subject: Initial checkin.

---
 src/farptr.h | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 src/farptr.h

(limited to 'src/farptr.h')

diff --git a/src/farptr.h b/src/farptr.h
new file mode 100644
index 0000000..1c3044b
--- /dev/null
+++ b/src/farptr.h
@@ -0,0 +1,57 @@
+// Code to access multiple segments within gcc.
+//
+// Copyright (C) 2008  Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#define READ8_SEG(SEG, var) ({                                          \
+    u8 __value;                                                         \
+    __asm__ __volatile__("movb %%" #SEG ":%1, %b0"                      \
+                         : "=Qi"(__value) : "m"(var));                  \
+    __value; })
+#define READ16_SEG(SEG, var) ({                                         \
+    u16 __value;                                                        \
+    __asm__ __volatile__("movw %%" #SEG ":%1, %w0"                      \
+                         : "=ri"(__value) : "m"(var));                  \
+    __value; })
+#define READ32_SEG(SEG, var) ({                                         \
+    u32 __value;                                                        \
+    __asm__ __volatile__("movl %%" #SEG ":%1, %0"                       \
+                         : "=ri"(__value) : "m"(var));                  \
+    __value; })
+#define WRITE8_SEG(SEG, var, value)                     \
+    __asm__ __volatile__("movb %b0, %%" #SEG ":%1"      \
+                         : : "Q"(value), "m"(var))
+#define WRITE16_SEG(SEG, var, value)                    \
+    __asm__ __volatile__("movw %w0, %%" #SEG ":%1"      \
+                         : : "r"(value), "m"(var))
+#define WRITE32_SEG(SEG, var, value)                    \
+    __asm__ __volatile__("movl %0, %%" #SEG ":%1"       \
+                         : : "r"(value), "m"(var))
+
+#define GET_VAR(seg, var) ({                                    \
+    typeof(var) __val;                                          \
+    if (__builtin_types_compatible_p(typeof(__val), u8))        \
+        __val = READ8_SEG(seg, var);                            \
+    else if (__builtin_types_compatible_p(typeof(__val), u16))  \
+        __val = READ16_SEG(seg, var);                           \
+    else if (__builtin_types_compatible_p(typeof(__val), u32))  \
+        __val = READ32_SEG(seg, var);                           \
+    __val; })
+
+#define SET_VAR(seg, var, val) do {                               \
+        if (__builtin_types_compatible_p(typeof(var), u8))        \
+            WRITE8_SEG(seg, var, (val));                          \
+        else if (__builtin_types_compatible_p(typeof(var), u16))  \
+            WRITE16_SEG(seg, var, (val));                         \
+        else if (__builtin_types_compatible_p(typeof(var), u32))  \
+            WRITE32_SEG(seg, var, (val));                         \
+    } while (0)
+
+#define SET_SEG(SEG, value)                                     \
+    __asm__ __volatile__("movw %w0, %%" #SEG : : "r"(value))
+#define GET_SEG(SEG) ({                                         \
+    u16 __seg;                                                  \
+    __asm__ __volatile__("movw %%" #SEG ", %w0" : "=r"(__seg)); \
+    __seg;})
+
-- 
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