storage.c

操作系统源代码

/* storage.c:  Code and data storage manipulations.  This includes labels. */

/*  This file is part of bc written for MINIX.
    Copyright (C) 1991, 1992 Free Software Foundation, Inc.

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License , or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; see the file COPYING.  If not, write to
    the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

    You may contact the author by:
       e-mail:  [e-mail]
      us-mail:  Philip A. Nelson
                Computer Science Department, 9062
                Western Washington University
                Bellingham, WA 98226-9062
       
*************************************************************************/

#include "bcdefs.h"
#include "global.h"
#include "proto.h"


/* Initialize the storage at the beginning of the run. */

void
init_storage ()
{

  /* Functions: we start with none and ask for more. */
  f_count = 0;
  more_functions ();
  f_names[0] = "(main)";

  /* Variables. */
  v_count = 0;
  more_variables ();
  
  /* Arrays. */
  a_count = 0;
  more_arrays ();

  /* Other things... */
  ex_stack = NULL;
  fn_stack = NULL;
  i_base = 10;
  o_base = 10;
  scale  = 0;
  c_code = FALSE;
  init_numbers();
}

/* Three functions for increasing the number of functions, variables, or
   arrays that are needed.  This adds another 32 of the requested object. */

void
more_functions (VOID)
{
  int old_count;
  int indx1, indx2;
  bc_function *old_f;
  bc_function *f;
  char **old_names;

  /* Save old information. */
  old_count = f_count;
  old_f = functions;
  old_names = f_names;

  /* Add a fixed amount and allocate new space. */
  f_count += STORE_INCR;
  functions = (bc_function *) bc_malloc (f_count*sizeof (bc_function));
  f_names = (char **) bc_malloc (f_count*sizeof (char *));

  /* Copy old ones. */
  for (indx1 = 0; indx1 < old_count; indx1++)
    {
      functions[indx1] = old_f[indx1];
      f_names[indx1] = old_names[indx1];
    }

  /* Initialize the new ones. */
  for (; indx1 < f_count; indx1++)
    {
      f = &functions[indx1];
      f->f_defined = FALSE;
      for (indx2 = 0; indx2 < BC_MAX_SEGS; indx2++)
	f->f_body [indx2] = NULL;
      f->f_code_size = 0;
      f->f_label = NULL;
      f->f_autos = NULL;
      f->f_params = NULL;
    }

  /* Free the old elements. */
  if (old_count != 0)
    {
      free (old_f);
      free (old_names);
    }
}

void
more_variables ()
{
  int indx;
  int old_count;
  bc_var **old_var;
  char **old_names;

  /* Save the old values. */
  old_count = v_count;
  old_var = variables;
  old_names = v_names;

  /* Increment by a fixed amount and allocate. */
  v_count += STORE_INCR;
  variables = (bc_var **) bc_malloc (v_count*sizeof(bc_var *));
  v_names = (char **) bc_malloc (v_count*sizeof(char *));

  /* Copy the old variables. */
  for (indx = 3; indx < old_count; indx++)
    variables[indx] = old_var[indx];

  /* Initialize the new elements. */
  for (; indx < v_count; indx++)
    variables[indx] = NULL;

  /* Free the old elements. */
  if (old_count != 0)
    {
      free (old_var);
      free (old_names);
    }
}

void
more_arrays ()
{
  int indx;
  int old_count;
  bc_var_array **old_ary;
  char **old_names;

  /* Save the old values. */
  old_count = a_count;
  old_ary = arrays;
  old_names = a_names;

  /* Increment by a fixed amount and allocate. */
  a_count += STORE_INCR;
  arrays = (bc_var_array **) bc_malloc (a_count*sizeof(bc_var_array *));
  a_names = (char **) bc_malloc (a_count*sizeof(char *));

  /* Copy the old arrays. */
  for (indx = 1; indx < old_count; indx++)
    arrays[indx] = old_ary[indx];


  /* Initialize the new elements. */
  for (; indx < v_count; indx++)
    arrays[indx] = NULL;

  /* Free the old elements. */
  if (old_count != 0)
    {
      free (old_ary);
      free (old_names);
    }
}


/* clear_func clears out function FUNC and makes it ready to redefine. */

void
clear_func (func)
     char func;
{
  bc_function *f;
  int indx;
  bc_label_group *lg;

  /* Set the pointer to the function. */
  f = &functions[func];
  f->f_defined = FALSE;

  /* Clear the code segments. */
  for (indx = 0; indx < BC_MAX_SEGS; indx++)
    {
      if (f->f_body[indx] != NULL)
	{
	  free (f->f_body[indx]);
	  f->f_body[indx] = NULL;
	}
    }

  f->f_code_size = 0;
  if (f->f_autos != NULL)
    {
      free_args (f->f_autos);
      f->f_autos = NULL;
    }
  if (f->f_params != NULL)
    {
      free_args (f->f_params);
      f->f_params = NULL;
    }
  while (f->f_label != NULL)
    {
      lg = f->f_label->l_next;
      free (f->f_label);
      f->f_label = lg;
    }
}


/*  Pop the function execution stack and return the top. */

int
fpop()
{
  fstack_rec *temp;
  int retval;
  
  if (fn_stack != NULL)
    {
      temp = fn_stack;
      fn_stack = temp->s_next;
      retval = temp->s_val;
      free (temp);
    }
  return (retval);
}


/* Push VAL on to the function stack. */

void
fpush (val)
     int val;
{
  fstack_rec *temp;
  
  temp = (fstack_rec *) bc_malloc (sizeof (fstack_rec));
  temp->s_next = fn_stack;
  temp->s_val = val;
  fn_stack = temp;
}


/* Pop and discard the top element of the regular execution stack. */

void
pop ()
{
  estack_rec *temp;
  
  if (ex_stack != NULL)
    {
      temp = ex_stack;
      ex_stack = temp->s_next;
      free_num (&temp->s_num);
      free (temp);
    }
}


/* Push a copy of NUM on to the regular execution stack. */

void
push_copy (num)
     bc_num num;
{
  estack_rec *temp;

  temp = (estack_rec *) bc_malloc (sizeof (estack_rec));
  temp->s_num = copy_num (num);
  temp->s_next = ex_stack;
  ex_stack = temp;
}


/* Push NUM on to the regular execution stack.  Do NOT push a copy. */

void
push_num (num)
     bc_num num;
{
  estack_rec *temp;

  temp = (estack_rec *) bc_malloc (sizeof (estack_rec));
  temp->s_num = num;
  temp->s_next = ex_stack;
  ex_stack = temp;
}


/* Make sure the ex_stack has at least DEPTH elements on it.
   Return TRUE if it has at least DEPTH elements, otherwise
   return FALSE. */

char
check_stack (depth)
     int depth;
{
  estack_rec *temp;

  temp = ex_stack;
  while ((temp != NULL) && (depth > 0))
    {
      temp = temp->s_next;
      depth--;
    }
  if (depth > 0)
    {
      rt_error ("Stack error.");
      return FALSE;
    }
  return TRUE;
}


/* The following routines manipulate simple variables and
   array variables. */

/* get_var returns a pointer to the variable VAR_NAME.  If one does not
   exist, one is created. */

bc_var *
get_var (var_name)
     int var_name;
{
  bc_var *var_ptr;

  var_ptr = variables[var_name];
  if (var_ptr == NULL)
    {
      var_ptr = variables[var_name] = (bc_var *) bc_malloc (sizeof (bc_var));
      init_num (&var_ptr->v_value);
    }
  return var_ptr;
}


/* get_array_num returns the address of the bc_num in the array
   structure.  If more structure is requried to get to the index,
   this routine does the work to create that structure. VAR_INDEX
   is a zero based index into the arrays storage array. INDEX is
   the index into the bc array. */

bc_num *
get_array_num (var_index, index)
     int var_index;
     long  index;
{
  bc_var_array *ary_ptr;
  bc_array *a_var;
  bc_array_node *temp;
  int log, ix, ix1;
  int sub [NODE_DEPTH];

  /* Get the array entry. */
  ary_ptr = arrays[var_index];
  if (ary_ptr == NULL)
    {
      ary_ptr = arrays[var_index] =
	(bc_var_array *) bc_malloc (sizeof (bc_var_array));
      ary_ptr->a_value = NULL;
      ary_ptr->a_next = NULL;
      ary_ptr->a_param = FALSE;
    }

  a_var = ary_ptr->a_value;
  if (a_var == NULL) {
    a_var = ary_ptr->a_value = (bc_array *) bc_malloc (sizeof (bc_array));
    a_var->a_tree = NULL;
    a_var->a_depth = 0;
  }

  /* Get the index variable. */
  sub[0] = index & NODE_MASK;
  ix = index >> NODE_SHIFT;
  log = 1;
  while (ix > 0 || log < a_var->a_depth)
    {
      sub[log] = ix & NODE_MASK;
      ix >>= NODE_SHIFT;
      log++;
    }
  
  /* Build any tree that is necessary. */
  while (log > a_var->a_depth)
    {
      temp = (bc_array_node *) bc_malloc (sizeof(bc_array_node));
      if (a_var->a_depth != 0)
	{
	  temp->n_items.n_down[0] = a_var->a_tree;
	  for (ix=1; ix < NODE_SIZE; ix++)
	    temp->n_items.n_down[ix] = NULL;
	}
      else
	{
	  for (ix=0; ix < NODE_SIZE; ix++)
	    temp->n_items.n_num[ix] = copy_num(_zero_);
	}
      a_var->a_tree = temp;
      a_var->a_depth++;
    }
  
  /* Find the indexed variable. */
  temp = a_var->a_tree;
  while ( log-- > 1)
    {
      ix1 = sub[log];
      if (temp->n_items.n_down[ix1] == NULL)
	{
	  temp->n_items.n_down[ix1] =
	    (bc_array_node *) bc_malloc (sizeof(bc_array_node));
	  temp = temp->n_items.n_down[ix1];
	  if (log > 1)
	    for (ix=0; ix < NODE_SIZE; ix++)
	      temp->n_items.n_down[ix] = NULL;
	  else
	    for (ix=0; ix < NODE_SIZE; ix++)
	      temp->n_items.n_num[ix] = copy_num(_zero_);
	}
      else
	temp = temp->n_items.n_down[ix1];
    }
  
  /* Return the address of the indexed variable. */
  return &(temp->n_items.n_num[sub[0]]);
}


/* Store the top of the execution stack into VAR_NAME.  
   This includes the special variables ibase, obase, and scale. */

void
store_var (var_name)
     int var_name;
{
  bc_var *var_ptr;
  long temp;
  char toobig;

  if (var_name > 2)
    {
      /* It is a simple variable. */
      var_ptr = get_var (var_name);
      if (var_ptr != NULL)
	{
	  free_num(&var_ptr->v_value);
	  var_ptr->v_value = copy_num (ex_stack->s_num);
	}
    }
  else
    {
      /* It is a special variable... */
      toobig = FALSE;
      if (is_neg (ex_stack->s_num))
	{
	  switch (var_name)
	    {
	    case 0:
	      rt_warn ("negative ibase, set to 2");
	      temp = 2;
	      break;
	    case 1:
	      rt_warn ("negative obase, set to 2");
	      temp = 2;
	      break;
	    case 2:
	      rt_warn ("negative scale, set to 0");