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-rw-r--r--src/farptr.h57
1 files changed, 57 insertions, 0 deletions
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;})
+