examples/libs/l4re/c++/mem_alloc/ma+rm.cc

Coarse grained memory allocation, in C++.

Coarse grained memory allocation, in C++.

 
/*
 * (c) 2009 Adam Lackorzynski <adam@os.inf.tu-dresden.de>
 *     economic rights: Technische Universität Dresden (Germany)
 *
 * This file is part of TUD:OS and distributed under the terms of the
 * GNU General Public License 2.
 * Please see the COPYING-GPL-2 file for details.
 */
 
#include <l4/re/mem_alloc>
#include <l4/re/rm>
#include <l4/re/env>
#include <l4/re/dataspace>
#include <l4/re/util/cap_alloc>
#include <l4/sys/err.h>
#include <cstdio>
#include <cstring>
 
static int allocate_mem(unsigned long size_in_bytes, unsigned long flags,
                        void **virt_addr)
{
  int r;
  L4::Cap<L4Re::Dataspace> d;
 
  /* Allocate a free capability index for our data space */
  d = L4Re::Util::cap_alloc.alloc<L4Re::Dataspace>();
  if (!d.is_valid())
    return -L4_ENOMEM;
 
  size_in_bytes = l4_trunc_page(size_in_bytes);
 
  /* Allocate memory via a dataspace */
  if ((r = L4Re::Env::env()->mem_alloc()->alloc(size_in_bytes, d, flags)))
    return r;
 
  /* Make the dataspace visible in our address space */
  *virt_addr = 0;
  if ((r = L4Re::Env::env()->rm()->attach(virt_addr, size_in_bytes,
                                          L4Re::Rm::F::Search_addr | L4Re::Rm::F::RW,
                                          L4::Ipc::make_cap_rw(d), 0,
                                          flags & L4Re::Mem_alloc::Super_pages
                                            ? L4_SUPERPAGESHIFT : L4_PAGESHIFT)))
    return r;
 
  /* Done, virtual address is in virt_addr */
  return 0;
}
 
static int free_mem(void *virt_addr)
{
  int r;
  L4::Cap<L4Re::Dataspace> ds;
 
  /* Detach memory from our address space */
  if ((r = L4Re::Env::env()->rm()->detach(virt_addr, &ds)))
    return r;
 
  /* Release and return capability slot to allocator */
  L4Re::Util::cap_alloc.free(ds, L4Re::Env::env()->task().cap());
 
  /* All went ok */
  return 0;
}
 
int main(void)
{
  void *virt;
 
  /* Allocate memory: 16k Bytes (usually) */
  if (allocate_mem(4 * L4_PAGESIZE, 0, &virt))
    return 1;
 
  printf("Allocated memory.\n");
 
  /* Do something with the memory */
  memset(virt, 0x12, 4 * L4_PAGESIZE);
 
  printf("Touched memory.\n");
 
  /* Free memory */
  if (free_mem(virt))
    return 2;
 
  printf("Freed and done. Bye.\n");
 
  return 0;
}