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#ifndef REALMODE_H
#define REALMODE_H
#ifndef ASSEMBLY
#include "stdint.h"
#include "registers.h"
#include "io.h"
/*
* Data structures and type definitions
*
*/
/* Segment:offset structure. Note that the order within the structure
* is offset:segment.
*/
typedef struct {
uint16_t offset;
uint16_t segment;
} __attribute__ (( packed )) segoff_t;
/* Macro hackery needed to stringify bits of inline assembly */
#define RM_XSTR(x) #x
#define RM_STR(x) RM_XSTR(x)
/* Drag in the selected real-mode transition library header */
#ifdef KEEP_IT_REAL
#include "libkir.h"
#else
#include "librm.h"
#endif
/*
* The API to some functions is identical between librm and libkir, so
* they are documented here, even though the prototypes are in librm.h
* and libkir.h.
*
*/
/*
* Declaration of variables in .data16
*
* To place a variable in the .data16 segment, declare it using the
* pattern:
*
* int __data16 ( foo );
* #define foo __use_data16 ( foo );
*
* extern uint32_t __data16 ( bar );
* #define bar __use_data16 ( bar );
*
* extern long __data16 ( baz ) = 0xff000000UL;
* #define bar __use_data16 ( baz );
*
* i.e. take a normal declaration, add __data16() around the variable
* name, and add a line saying "#define <name> __use_data16 ( <name> )
*
* You can then access them just like any other variable, for example
*
* int x = foo + bar;
*
* This magic is achieved at a cost of only around 7 extra bytes per
* group of accesses to .data16 variables. When using KEEP_IT_REAL,
* there is no extra cost.
*
* You should place variables in .data16 when they need to be accessed
* by real-mode code. Real-mode assembly (e.g. as created by
* REAL_EXEC()) can access these variables via the usual data segment.
* You can therefore write something like
*
* static uint16_t __data16 ( foo );
* #define foo __use_data16 ( foo )
*
* int bar ( void ) {
* REAL_EXEC ( baz,
* "int $0xff\n\t"
* "movw %ax, foo",
* ... );
* return foo;
* }
*
* Variables may also be placed in .text16 using __text16 and
* __use_text16. Some variables (e.g. chained interrupt vectors) fit
* most naturally in .text16; most should be in .data16.
*/
/*
* void copy_to_real ( uint16_t dest_seg, uint16_t dest_off,
* void *src, size_t n )
* void copy_from_real ( void *dest, uint16_t src_seg, uint16_t src_off,
* size_t n )
*
* These functions can be used to copy data to and from arbitrary
* locations in base memory.
*/
/*
* put_real ( variable, uint16_t dest_seg, uint16_t dest_off )
* get_real ( variable, uint16_t src_seg, uint16_t src_off )
*
* These macros can be used to read or write single variables to and
* from arbitrary locations in base memory. "variable" must be a
* variable of either 1, 2 or 4 bytes in length.
*/
/*
* REAL_CALL ( routine, num_out_constraints, out_constraints,
* in_constraints, clobber )
* REAL_EXEC ( name, asm_code_str, num_out_constraints, out_constraints,
* in_constraints, clobber )
*
* If you have a pre-existing real-mode routine that you want to make
* a far call to, use REAL_CALL. If you have a code fragment that you
* want to copy down to base memory, execute, and then remove, use
* REAL_EXEC.
*
* out_constraints must be of the form OUT_CONSTRAINTS(constraints),
* and in_constraints must be of the form IN_CONSTRAINTS(constraints),
* where "constraints" is a constraints list as would be used in an
* inline __asm__()
*
* clobber must be of the form CLOBBER ( clobber_list ), where
* "clobber_list" is a clobber list as would be used in an inline
* __asm__().
*
* These are best illustrated by example. To write a character to the
* console using INT 10, you would do something like:
*
* REAL_EXEC ( rm_test_librm,
* "int $0x10",
* 1,
* OUT_CONSTRAINTS ( "=a" ( discard ) ),
* IN_CONSTRAINTS ( "a" ( 0x0e00 + character ),
* "b" ( 1 ) ),
* CLOBBER ( "ebx", "ecx", "edx", "ebp", "esi", "edi" ) );
*
* IMPORTANT: gcc does not automatically assume that input operands
* get clobbered. The only way to specify that an input operand may
* be modified is to also specify it as an output operand; hence the
* "(discard)" in the above code.
*/
#warning "realmode.h contains placeholders for obsolete macros"
/* Just for now */
#define SEGMENT(x) ( virt_to_phys ( x ) >> 4 )
#define OFFSET(x) ( virt_to_phys ( x ) & 0xf )
#define SEGOFF(x) { OFFSET(x), SEGMENT(x) }
/* To make basemem.c compile */
extern int lock_real_mode_stack;
extern char *real_mode_stack;
extern char real_mode_stack_size[];
#define RM_FRAGMENT(name,asm) \
void name ( void ) {} \
extern char name ## _size[];
#endif /* ASSEMBLY */
#endif /* REALMODE_H */
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