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// Memory access to BIOS variables.
//
// Copyright (C) 2008-2013 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU LGPLv3 license.
#ifndef __BIOSVAR_H
#define __BIOSVAR_H
#include "config.h" // SEG_BDA
#include "farptr.h" // GET_FARVAR
#include "std/bda.h" // struct bios_data_area_s
/****************************************************************
* Interupt vector table
****************************************************************/
#define GET_IVT(vector) \
GET_FARVAR(SEG_IVT, ((struct rmode_IVT *)0)->ivec[vector])
#define SET_IVT(vector, segoff) \
SET_FARVAR(SEG_IVT, ((struct rmode_IVT *)0)->ivec[vector], segoff)
#define FUNC16(func) ({ \
ASSERT32FLAT(); \
extern void func (void); \
SEGOFF(SEG_BIOS, (u32)func - BUILD_BIOS_ADDR); \
})
/****************************************************************
* Bios Data Area (BDA)
****************************************************************/
// Accessor functions
#define GET_BDA(var) \
GET_FARVAR(SEG_BDA, ((struct bios_data_area_s *)0)->var)
#define SET_BDA(var, val) \
SET_FARVAR(SEG_BDA, ((struct bios_data_area_s *)0)->var, (val))
// Helper function to set the bits of the equipment_list_flags variable.
static inline void set_equipment_flags(u16 clear, u16 set) {
u16 eqf = GET_BDA(equipment_list_flags);
SET_BDA(equipment_list_flags, (eqf & ~clear) | set);
}
/****************************************************************
* Extended Bios Data Area (EBDA)
****************************************************************/
// The initial size and location of EBDA
#define EBDA_SIZE_START \
DIV_ROUND_UP(sizeof(struct extended_bios_data_area_s), 1024)
#define EBDA_SEGMENT_START \
FLATPTR_TO_SEG(BUILD_LOWRAM_END - EBDA_SIZE_START*1024)
// Accessor functions
static inline u16 get_ebda_seg(void) {
return GET_BDA(ebda_seg);
}
static inline struct extended_bios_data_area_s *
get_ebda_ptr(void)
{
ASSERT32FLAT();
return MAKE_FLATPTR(get_ebda_seg(), 0);
}
#define GET_EBDA(eseg, var) \
GET_FARVAR(eseg, ((struct extended_bios_data_area_s *)0)->var)
#define SET_EBDA(eseg, var, val) \
SET_FARVAR(eseg, ((struct extended_bios_data_area_s *)0)->var, (val))
/****************************************************************
* Global variables
****************************************************************/
#if MODE16 == 0 && MODESEGMENT == 1
// In 32bit segmented mode %cs may not be readable and the code may be
// relocated. The entry code sets up %gs with a readable segment and
// the code offset can be determined by get_global_offset().
#define GLOBAL_SEGREG GS
static inline u32 __attribute_const get_global_offset(void) {
u32 ret;
asm(" calll 1f\n"
"1:popl %0\n"
" subl $1b, %0"
: "=r"(ret));
return ret;
}
#else
#define GLOBAL_SEGREG CS
static inline u32 __attribute_const get_global_offset(void) {
return 0;
}
#endif
static inline u16 get_global_seg(void) {
return GET_SEG(GLOBAL_SEGREG);
}
#define GET_GLOBAL(var) \
GET_VAR(GLOBAL_SEGREG, *(typeof(&(var)))((void*)&(var) \
+ get_global_offset()))
#define SET_GLOBAL(var, val) do { \
ASSERT32FLAT(); \
(var) = (val); \
} while (0)
#if MODESEGMENT
#define GLOBALFLAT2GLOBAL(var) ((typeof(var))((void*)(var) - BUILD_BIOS_ADDR))
#else
#define GLOBALFLAT2GLOBAL(var) (var)
#endif
// Access a "flat" pointer known to point to the f-segment.
#define GET_GLOBALFLAT(var) GET_GLOBAL(*GLOBALFLAT2GLOBAL(&(var)))
/****************************************************************
* "Low" memory variables
****************************************************************/
extern u8 _zonelow_seg, zonelow_base[];
#define SEG_LOW ((u32)&_zonelow_seg)
#if MODESEGMENT
#define GET_LOW(var) GET_FARVAR(SEG_LOW, (var))
#define SET_LOW(var, val) SET_FARVAR(SEG_LOW, (var), (val))
#define LOWFLAT2LOW(var) ((typeof(var))((void*)(var) - (u32)zonelow_base))
#else
#define GET_LOW(var) (var)
#define SET_LOW(var, val) do { (var) = (val); } while (0)
#define LOWFLAT2LOW(var) (var)
#endif
#define GET_LOWFLAT(var) GET_LOW(*LOWFLAT2LOW(&(var)))
#define SET_LOWFLAT(var, val) SET_LOW(*LOWFLAT2LOW(&(var)), (val))
#endif // __BIOSVAR_H