hw_memory.c

这个是LINUX下的GDB调度工具的源码

  /* get the address from the stack */
  {
    int nr_cells = device_nr_address_cells(device_parent(me));
    if (alignment != 0) {
      if (n_stack_args != stackp) {
	if (n_stack_args == stackp + nr_cells)
	  DTRACE(memory, ("claim - extra address argument ignored\n"));
	else
	  device_error(me, "claim - incorrect number of arguments (optional addr)");
      }
      address = 0;
    }
    else {
      int i;
      if (n_stack_args != stackp + nr_cells)
	device_error(me, "claim - incorrect number of arguments (addr missing)");
      for (i = 0; i < nr_cells - 1; i++) {
	if (stack_args[stackp] != 0)
	  device_error(me, "claim - multi-cell addresses not supported");
	stackp++;
      }
      address = stack_args[stackp];
    }
  }

  /* check that there is space for the result */
  if (n_stack_returns != 0
      && n_stack_returns != device_nr_address_cells(device_parent(me)))
    device_error(me, "claim - invalid number of return arguments");

  /* find a chunk candidate, either according to address or alignment */
  if (alignment == 0) {
    chunk = hw_memory->heap;
    while (chunk != NULL) {
      if ((address + size) <= (chunk->address + chunk->size))
	break;
      chunk = chunk->next;
    }
    if (chunk == NULL || address < chunk->address || !chunk->available)
      device_error(me, "failed to allocate %ld bytes at 0x%lx",
		   (unsigned long)size, (unsigned long)address);
    DTRACE(memory, ("claim - address=0x%lx size=0x%lx\n",
		    (unsigned long)address,
		    (unsigned long)size));
  }
  else {
    /* adjust the alignment so that it is a power of two */
    unsigned_word align_mask = 1;
    while (align_mask < alignment && align_mask != 0)
      align_mask <<= 1;
    if (align_mask == 0)
      device_error(me, "alignment 0x%lx is to large", (unsigned long)alignment);
    align_mask -= 1;
    /* now find an aligned chunk that fits */
    chunk = hw_memory->heap;
    while (chunk != NULL) {
      address = ((chunk->address + align_mask) & ~align_mask);
      if ((chunk->available)
	  && (chunk->address + chunk->size >= address + size))
	break;
      chunk = chunk->next;
    }
    if (chunk == NULL)
      device_error(me, "failed to allocate %ld bytes with alignment %ld",
		   (unsigned long)size, (unsigned long)alignment);
    DTRACE(memory, ("claim - size=0x%lx alignment=%ld (0x%lx), address=0x%lx\n",
		    (unsigned long)size,
		    (unsigned long)alignment,
		    (unsigned long)alignment,
		    (unsigned long)address));
  }

  /* break off a bit before this chunk if needed */
  ASSERT(address >= chunk->address);
  if (address > chunk->address) {
    hw_memory_chunk *next_chunk = ZALLOC(hw_memory_chunk);
    /* insert a new chunk */
    next_chunk->next = chunk->next;
    chunk->next = next_chunk;
    /* adjust the address/size */
    next_chunk->address = address;
    next_chunk->size = chunk->address + chunk->size - next_chunk->address;
    next_chunk->available = 1;
    chunk->size = next_chunk->address - chunk->address;
    /* make this new chunk the one to allocate */
    chunk = next_chunk;
  }
  ASSERT(address == chunk->address);

  /* break off a bit after this chunk if needed */
  ASSERT(address + size <= chunk->address + chunk->size);
  if (address + size < chunk->address + chunk->size) {
    hw_memory_chunk *next_chunk = ZALLOC(hw_memory_chunk);
    /* insert it in to the list */
    next_chunk->next = chunk->next;
    chunk->next = next_chunk;
    /* adjust the address/size */
    next_chunk->address = address + size;
    next_chunk->size = chunk->address + chunk->size - next_chunk->address;
    next_chunk->available = 1;
    chunk->size = next_chunk->address - chunk->address;
  }
  ASSERT(address + size == chunk->address + chunk->size);

  /* now allocate/return it */
  chunk->available = 0;
  hw_memory_set_available(device_instance_device(instance), hw_memory);
  if (n_stack_returns > 0) {
    int i;
    for (i = 0; i < n_stack_returns - 1; i++)
      stack_returns[i] = 0;
    stack_returns[n_stack_returns - 1] = address;
  }

  return 0;
}


static int
hw_memory_instance_release(device_instance *instance,
			   int n_stack_args,
			   unsigned_cell stack_args[/*n_stack_args*/],
			   int n_stack_returns,
			   unsigned_cell stack_returns[/*n_stack_returns*/])
{
  hw_memory_device *hw_memory = device_instance_data(instance);
  device *me = device_instance_device(instance);
  unsigned_word length;
  unsigned_word address;
  int stackp = 0;
  hw_memory_chunk *chunk;
  
  /* get the length from the stack */
  {
    int i;
    int nr_cells = device_nr_size_cells(device_parent(me));
    if (n_stack_args < stackp + nr_cells)
      device_error(me, "release - incorrect number of arguments (length missing)");
    for (i = 0; i < nr_cells - 1; i++) {
      if (stack_args[stackp] != 0)
	device_error(me, "release - multi-cell length not supported");
      stackp++;
    }
    length = stack_args[stackp];
    stackp++;
  }

  /* get the address from the stack */
  {
    int i;
    int nr_cells = device_nr_address_cells(device_parent(me));
    if (n_stack_args != stackp + nr_cells)
      device_error(me, "release - incorrect number of arguments (addr missing)");
    for (i = 0; i < nr_cells - 1; i++) {
      if (stack_args[stackp] != 0)
	device_error(me, "release - multi-cell addresses not supported");
      stackp++;
    }
    address = stack_args[stackp];
  }

  /* returns ok */
  if (n_stack_returns != 0)
    device_error(me, "release - nonzero number of results");

  /* try to free the corresponding memory chunk */
  chunk = hw_memory->heap;
  while (chunk != NULL) {
    if (chunk->address == address
	&& chunk->size == length) {
      /* an exact match */
      if (chunk->available)
	device_error(me, "memory chunk 0x%lx (size 0x%lx) already available",
		     (unsigned long)address,
		     (unsigned long)length);
      else {
	/* free this chunk */
	DTRACE(memory, ("release - address=0x%lx, length=0x%lx\n",
			(unsigned long) address,
			(unsigned long) length));
	chunk->available = 1;
	break;
      }
    }
    else if (chunk->address >= address
	     && chunk->address + chunk->size <= address + length) {
      /* a sub region */
      if (!chunk->available) {
	DTRACE(memory, ("release - address=0x%lx, size=0x%lx within region 0x%lx length 0x%lx\n",
			(unsigned long) chunk->address,
			(unsigned long) chunk->size,
			(unsigned long) address,
			(unsigned long) length));
	chunk->available = 1;
      }
    }
    chunk = chunk->next;
  }
  if (chunk == NULL) {
    printf_filtered("warning: released chunks within region 0x%lx..0x%lx\n",
		    (unsigned long)address,
		    (unsigned long)(address + length - 1));
  }

  /* check for the chance to merge two adjacent available memory chunks */
  chunk = hw_memory->heap;
  while (chunk != NULL) {
    if (chunk->available
	&& chunk->next != NULL && chunk->next->available) {
      /* adjacent */
      hw_memory_chunk *delete = chunk->next;
      ASSERT(chunk->address + chunk->size == delete->address);
      chunk->size += delete->size;
      chunk->next = delete->next;
      zfree(delete);
    }
    else {
      chunk = chunk->next;
    }
  }

  /* update the corresponding property */
  hw_memory_set_available(device_instance_device(instance), hw_memory);

  return 0;
}


static device_instance_methods hw_memory_instance_methods[] = {
  { "claim", hw_memory_instance_claim },
  { "release", hw_memory_instance_release },
  { NULL, },
};

static device_instance_callbacks const hw_memory_instance_callbacks = {
  hw_memory_instance_delete,
  NULL /*read*/, NULL /*write*/, NULL /*seek*/,
  hw_memory_instance_methods
};

static device_instance *
hw_memory_create_instance(device *me,
			  const char *path,
			  const char *args)
{
  return device_create_instance_from(me, NULL,
				     device_data(me), /* nothing better */
				     path, args,
				     &hw_memory_instance_callbacks);
}

static device_callbacks const hw_memory_callbacks = {
  { hw_memory_init_address, },
  { NULL, }, /* address */
  { NULL, }, /* IO */
  { NULL, }, /* DMA */
  { NULL, }, /* interrupt */
  { NULL, }, /* unit */
  hw_memory_create_instance,
};

const device_descriptor hw_memory_device_descriptor[] = {
  { "memory", hw_memory_create, &hw_memory_callbacks },
  { NULL },
};

#endif /* _HW_MEMORY_C_ */