@node _go32_dpmi_get_free_memory_information, dpmi
@subheading Syntax

@example
#include <dpmi.h

int _go32_dpmi_get_free_memory_information(_go32_dpmi_meminfo *info);
@end example

@subheading Description

This function fills in the following structure:

@example
typedef struct @{
  u_long available_memory;
  u_long available_pages;
  u_long available_lockable_pages;
  u_long linear_space;
  u_long unlocked_pages;
  u_long available_physical_pages;
  u_long total_physical_pages;
  u_long free_linear_space;
  u_long max_pages_in_paging_file;
  u_long reserved[3];
@} _go32_dpmi_meminfo;
@end example

The only field that is guaranteed to have useful data is
@code{available_memory}.  Any unavailable field has -1 in it. 

@subheading Return Value

Zero on success, nonzero on failure.

@subheading Portability

@portability !ansi, !posix

@subheading Example

@example
int phys_mem_left()
@{
  _go32_dpmi_meminfo info;
  _go32_dpmi_get_free_memory_information(&info);
  if (info.available_physical_pages != -1)
    return info.available_physical_pages * 4096;
  return info.available_memory;
@}
@end example

@c ----------------------------------------------------------------------
@node _go32_dpmi_simulate_fcall, dpmi
@subheading Syntax

@example
#include <dpmi.h>

int _go32_dpmi_simulate_fcall(_go32_dpmi_registers *regs);
@end example

@subheading Description

@xref{DPMI Overview}.

This function simulates a real-mode far call to a function that returns
with a far return.  The registers are set up from @var{regs}, including
@code{CS} and @code{IP}, which indicate the address of the call.  Any
registers the function modifies are reflected in @var{regs} on return.

If @code{SS} and @code{SP} are both zero, a small temporary stack is
used when in real mode.  If not, they are used @emph{as is}.  It's a good
idea to use @code{memset} to initialize the register structure before
using it.

@subheading Return Value

Zero on success, nonzero on failure.

@subheading Portability

@portability !ansi, !posix

@subheading Example

@example
_go32_dpmi_registers r;
r.x.ax = 47;
r.x.cs = some_segment;
r.x.ip = some_offset;
r.x.ss = r.x.sp = 0;
_go32_dpmi_simulate_fcall(&r);
printf("returns %d\n", r.x.ax);
@end example

@c ----------------------------------------------------------------------
@node _go32_dpmi_simulate_fcall_iret, dpmi
@subheading Syntax

@example
#include <dpmi.h>

int _go32_dpmi_simulate_fcall_iret(_go32_dpmi_registers *regs);
@end example

@subheading Description

@xref{DPMI Overview}.

This function simulates a real-mode far call to a function that returns
with an @code{iret} instruction.  The registers are set up from
@var{regs}, including @code{CS} and @code{IP}, which indicate the
address of the call.  Any registers the function modifies are reflected
in @var{regs} on return. 

If @code{SS} and @code{SP} are both zero, a small temporary stack is
used when in real mode.  If not, they are used @emph{as is}.  It's a good
idea to use @code{memset} to initialize the register structure before
using it.

@subheading Return Value

Zero on success, nonzero on failure.

@subheading Portability

@portability !ansi, !posix

@subheading Example

@example
_go32_dpmi_registers r;
r.x.ax = 47;
r.x.cs = some_segment;
r.x.ip = some_offset;
r.x.ss = r.x.sp = 0;
_go32_dpmi_simulate_fcall_iret(&r);
printf("returns %d\n", r.x.ax);
@end example

@c ----------------------------------------------------------------------
@node _go32_dpmi_simulate_int, dpmi
@subheading Syntax

@example
#include <dpmi.h>

int _go32_dpmi_simulate_int(int vector, _go32_dpmi_registers *regs);
@end example

@subheading Description

@xref{DPMI Overview}.

This function simulates a real-mode interrup.  The registers are set up from
@var{regs}, including @code{CS} and @code{IP}, which indicate the
address of the call.  Any registers the function modifies are reflected
in @var{regs} on return. 

If @code{SS} and @code{SP} are both zero, a small temporary stack is
used when in real mode.  If not, they are used @emph{as is}.  It's a good
idea to use @code{memset} to initialize the register structure before
using it.

@subheading Return Value

Zero on success, nonzero on failure.

@subheading Portability

@portability !ansi, !posix

@subheading Example

@example
_go32_dpmi_registers r;
r.h.ah = 0x08;
r.h.dl = 0x80; /* drive C: */
r.x.ss = r.x.sp = 0;
_go32_dpmi_simulate_int(0x13, &r);
printf("disk is %d cyl, %d head, %d sect\n",
       r.h.ch | ((r.x.cl<<2)&0x300),
       r.h.dh, r.h.cl & 0x3f));
@end example

@c ----------------------------------------------------------------------
@node _go32_my_cs, go32
@subheading Syntax

@example
#include <go32.h>

u_short _go32_my_cs();
@end example

@subheading Description

Returns the current @code{CS}.  This is useful for setting up interrupt
vectors and such. 

@subheading Return Value

@code{CS}

@subheading Portability

@portability !ansi, !posix

@c ----------------------------------------------------------------------
@node _go32_my_ds, go32
@subheading Syntax

@example
#include <go32.h>

u_short _go32_my_ds();
@end example

@subheading Description

Returns the current @code{DS}.  This is useful for moving memory
and such. 

@subheading Return Value

@code{DS}

@subheading Portability

@portability !ansi, !posix

@c ----------------------------------------------------------------------
@node _go32_my_ss, go32
@subheading Syntax

@example
#include <go32.h>

u_short _go32_my_ss();
@end example

@subheading Description

Returns the current @code{SS}.  This is useful for moving memory
and such. 

@subheading Return Value

@code{SS}

@subheading Portability

@portability !ansi, !posix

@c ----------------------------------------------------------------------
@node _go32_conventional_mem_selector, go32
@subheading Syntax

@example
#include <go32.h>

u_short _go32_conventional_mem_selector();
@end example

@subheading Description

This function returns a selector which has a physical base address
corresponding to the beginning of conventional memory.  This selector
can be used as a parameter to @code{movedata} (@pxref{movedata}) to
manipulate memory in the conventional address space. 

@subheading Return Value

The selector.

@subheading Portability

@portability !ansi, !posix

@subheading Example

@example
short blank_row_buf[ScreenCols()];
/* scroll screen */
movedata(_go32_conventional_mem_selector(), 0xb8000 + ScreenCols()*2,
         _go32_conventional_mem_selector(), 0xb8000,
         ScreenCols() * (ScreenRows()-1) * 2);
/* fill last row */
movedata(_go32_my_ds, (int)blank_row_buf,
         _go32_conventional_mem_selector(),
            0xb8000 + ScreenCols()*(ScreenRows()-1)*2,
          ScreenCols() * 2);
@end example