static void *map_first_meg(uintptr_t phys_addr, size_t len)
{
if (realmem_map)
return realmem_map + phys_addr;
realmem_map = valloc(1024 * 1024);
if (!realmem_map)
return ERROR_PTR;
if (__djgpp_map_physical_memory(realmem_map, (1024 * 1024), 0)) {
free(realmem_map);
realmem_map = NULL;
return ERROR_PTR;
}
return realmem_map + phys_addr;
}
/* Attempts to mmap sufficient memory for the specified video mode
* over the memory pointed to by vdriver_fbuf, which must be
* page-aligned. Returns TRUE if successful, else FALSE.
*/
boolean_t
vgahost_mmap_linear_fbuf (const vga_mode_t *mode)
{
boolean_t success_p;
success_p = FALSE; /* Default */
if (mode->phys_base_addr != 0) /* do we have a linear frame buffer? */
{
if (!__djgpp_map_physical_memory (vdriver_fbuf,
((mode->height * mode->row_bytes
+ DPMI_PAGE_SIZE - 1)
& ~(DPMI_PAGE_SIZE - 1)),
mode->phys_base_addr))
{
success_p = TRUE;
}
else if (mode->screen_selector != 0 && try_to_use_fat_ds_vga_hack_p)
{
/* We failed to mmap it the DPMI 1.0 way, so we'll see if we
* can use the fat %ds hack.
*/
if (__djgpp_nearptr_enable ())
{
unsigned long executor_base = 0, fbuf_base = 0;
if (!__dpmi_get_segment_base_address (dos_pm_ds, &executor_base)
&& !__dpmi_get_segment_base_address (mode->screen_selector,
&fbuf_base))
{
vdriver_fbuf = (uint8 *) (fbuf_base - executor_base);
actually_using_fat_ds_vga_hack_p = TRUE;
success_p = TRUE;
}
}
}
}
if (success_p)
{
/* Cool beans. Note that the screen is in our address space. */
vga_screen_selector = dos_pm_ds;
}
return success_p;
}
