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