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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.
#ifndef __FARPTR_H
#define __FARPTR_H
#include "ioport.h" // insb
// Dummy definitions used to make sure gcc understands dependencies
// between SET_SEG and GET/READ/WRITE_SEG macros.
extern u16 __segment_ES, __segment_CS, __segment_DS, __segment_SS;
// Low level macros for reading/writing memory via a segment selector.
#define READ8_SEG(SEG, var) ({ \
typeof(var) __value; \
__asm__("movb %%" #SEG ":%1, %b0" : "=Qi"(__value) \
: "m"(var), "m"(__segment_ ## SEG)); \
__value; })
#define READ16_SEG(SEG, var) ({ \
typeof(var) __value; \
__asm__("movw %%" #SEG ":%1, %w0" : "=ri"(__value) \
: "m"(var), "m"(__segment_ ## SEG)); \
__value; })
#define READ32_SEG(SEG, var) ({ \
typeof(var) __value; \
__asm__("movl %%" #SEG ":%1, %0" : "=ri"(__value) \
: "m"(var), "m"(__segment_ ## SEG)); \
__value; })
#define WRITE8_SEG(SEG, var, value) \
__asm__("movb %b0, %%" #SEG ":%1" : \
: "Q"(value), "m"(var), "m"(__segment_ ## SEG))
#define WRITE16_SEG(SEG, var, value) \
__asm__("movw %w0, %%" #SEG ":%1" : \
: "r"(value), "m"(var), "m"(__segment_ ## SEG))
#define WRITE32_SEG(SEG, var, value) \
__asm__("movl %0, %%" #SEG ":%1" : \
: "r"(value), "m"(var), "m"(__segment_ ## SEG))
// Low level macros for getting/setting a segment register.
#define __SET_SEG(SEG, value) \
__asm__("movw %w1, %%" #SEG : "=m"(__segment_ ## SEG) \
: "r"(value))
#define __GET_SEG(SEG) ({ \
u16 __seg; \
__asm__("movw %%" #SEG ", %w0" : "=r"(__seg) \
: "m"(__segment_ ## SEG)); \
__seg;})
// Macros for automatically choosing the appropriate memory size
// access method.
extern void __force_link_error__unknown_type();
#define __GET_VAR(seg, var) ({ \
typeof(var) __val; \
if (__builtin_types_compatible_p(typeof(__val), u8) \
|| __builtin_types_compatible_p(typeof(__val), s8)) \
__val = READ8_SEG(seg, var); \
else if (__builtin_types_compatible_p(typeof(__val), u16) \
|| __builtin_types_compatible_p(typeof(__val), s16)) \
__val = READ16_SEG(seg, var); \
else if (__builtin_types_compatible_p(typeof(__val), u32) \
|| __builtin_types_compatible_p(typeof(__val), s32)) \
__val = READ32_SEG(seg, var); \
else \
__force_link_error__unknown_type(); \
__val; })
#define __SET_VAR(seg, var, val) do { \
if (__builtin_types_compatible_p(typeof(var), u8) \
|| __builtin_types_compatible_p(typeof(var), s8)) \
WRITE8_SEG(seg, var, (val)); \
else if (__builtin_types_compatible_p(typeof(var), u16) \
|| __builtin_types_compatible_p(typeof(var), s16)) \
WRITE16_SEG(seg, var, (val)); \
else if (__builtin_types_compatible_p(typeof(var), u32) \
|| __builtin_types_compatible_p(typeof(var), s32)) \
WRITE32_SEG(seg, var, (val)); \
else \
__force_link_error__unknown_type(); \
} while (0)
// Macros for accessing a variable in another segment. (They
// automatically update the %es segment and then make the appropriate
// access.)
#define __GET_FARVAR(seg, var) ({ \
SET_SEG(ES, (seg)); \
GET_VAR(ES, (var)); })
#define __SET_FARVAR(seg, var, val) do { \
typeof(var) __sfv_val = (val); \
SET_SEG(ES, (seg)); \
SET_VAR(ES, (var), __sfv_val); \
} while (0)
// Macros for accesssing a 32bit pointer from 16bit mode. (They
// automatically update the %es segment, break the pointer into
// segment/offset, and then make the access.)
#define __GET_FARPTR(ptr) ({ \
typeof(&(ptr)) __ptr = &(ptr); \
GET_FARVAR(FARPTR_TO_SEG(__ptr) \
, *(typeof(__ptr))FARPTR_TO_OFFSET(__ptr)); })
#define __SET_FARPTR(ptr, val) do { \
typeof (&(ptr)) __ptr = &(ptr); \
SET_FARVAR(FARPTR_TO_SEG(__ptr) \
, *(typeof(__ptr))FARPTR_TO_OFFSET(__ptr) \
, (val)); \
} while (0)
// Macros for converting to/from 32bit style pointers to their
// equivalent 16bit segment/offset values.
#define FARPTR_TO_SEG(p) (((u32)(p)) >> 4)
#define FARPTR_TO_OFFSET(p) (((u32)(p)) & 0xf)
#define MAKE_FARPTR(seg,off) ((void*)(((seg)<<4)+(off)))
#ifdef MODE16
// Definitions when in 16 bit mode.
#define GET_FARVAR(seg, var) __GET_FARVAR((seg), (var))
#define SET_FARVAR(seg, var, val) __SET_FARVAR((seg), (var), (val))
#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)
#define GET_FARPTR(ptr) __GET_FARPTR(ptr)
#define SET_FARPTR(ptr, val) __SET_FARPTR((ptr), (val))
static inline void insb_far(u16 port, void *farptr, u16 count) {
SET_SEG(ES, FARPTR_TO_SEG(farptr));
insb(port, (u8*)FARPTR_TO_OFFSET(farptr), count);
}
static inline void insw_far(u16 port, void *farptr, u16 count) {
SET_SEG(ES, FARPTR_TO_SEG(farptr));
insw(port, (u16*)FARPTR_TO_OFFSET(farptr), count);
}
static inline void insl_far(u16 port, void *farptr, u16 count) {
SET_SEG(ES, FARPTR_TO_SEG(farptr));
insl(port, (u32*)FARPTR_TO_OFFSET(farptr), count);
}
static inline void outsb_far(u16 port, void *farptr, u16 count) {
SET_SEG(ES, FARPTR_TO_SEG(farptr));
outsb(port, (u8*)FARPTR_TO_OFFSET(farptr), count);
}
static inline void outsw_far(u16 port, void *farptr, u16 count) {
SET_SEG(ES, FARPTR_TO_SEG(farptr));
outsw(port, (u16*)FARPTR_TO_OFFSET(farptr), count);
}
static inline void outsl_far(u16 port, void *farptr, u16 count) {
SET_SEG(ES, FARPTR_TO_SEG(farptr));
outsl(port, (u32*)FARPTR_TO_OFFSET(farptr), count);
}
#else
// In 32-bit mode there is no need to mess with the segments.
#define GET_FARVAR(seg, var) \
(*((typeof(&(var)))MAKE_FARPTR((seg), (u32)&(var))))
#define SET_FARVAR(seg, var, val) \
do { GET_FARVAR((seg), (var)) = (val); } while (0)
#define GET_VAR(seg, var) (var)
#define SET_VAR(seg, var, val) do { (var) = (val); } while (0)
#define SET_SEG(SEG, value) ((void)(value))
#define GET_SEG(SEG) 0
#define GET_FARPTR(ptr) (ptr)
#define SET_FARPTR(ptr, val) do { (ptr) = (val); } while (0)
#define insb_far(port, farptr, count) insb(port, farptr, count)
#define insw_far(port, farptr, count) insw(port, farptr, count)
#define insl_far(port, farptr, count) insl(port, farptr, count)
#define outsb_far(port, farptr, count) outsb(port, farptr, count)
#define outsw_far(port, farptr, count) outsw(port, farptr, count)
#define outsl_far(port, farptr, count) outsl(port, farptr, count)
#endif
#endif // farptr.h