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// 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;})
#ifdef MODE16
#define GET_VAR(seg, var) __GET_VAR(seg, var)
#define SET_VAR(seg, var, val) __SET_VAR(seg, var, val)
#define SET_SEG(SEG, value) __SET_SEG(SEG, value)
#define GET_SEG(SEG) __GET_SEG(SEG)
#else
// In 32-bit mode there is no need to mess with the segments.
#define GET_VAR(seg, var) (var)
#define SET_VAR(seg, var, val) (var) = (val)
#define SET_SEG(SEG, value) ((void)(value))
#define GET_SEG(SEG) 0
#endif
#define GET_FARVAR(seg, var) ({ \
SET_SEG(ES, (seg)); \
GET_VAR(ES, (var)); })
#define SET_FARVAR(seg, var, val) do { \
SET_SEG(ES, (seg)); \
SET_VAR(ES, (var), val); \
} while (0)
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