vvp/codes.cc

   1 /*
   2  * Copyright (c) 2001 Stephen Williams (steve@icarus.com)
   3  *
   4  *    This source code is free software; you can redistribute it
   5  *    and/or modify it in source code form under the terms of the GNU
   6  *    General Public License as published by the Free Software
   7  *    Foundation; either version 2 of the License, or (at your option)
   8  *    any later version.
   9  *
  10  *    This program is distributed in the hope that it will be useful,
  11  *    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *    GNU General Public License for more details.
  14  *
  15  *    You should have received a copy of the GNU General Public License
  16  *    along with this program; if not, write to the Free Software
  17  *    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  18  */
  19 #ifdef HAVE_CVS_IDENT
  20 #ident "$Id: codes.cc,v 1.14 2003/08/01 00:58:03 steve Exp $"
  21 #endif
  22
  23 # include  "codes.h"
  24 # include  "statistics.h"
  25 # include  <string.h>
  26 # include  <assert.h>
  27
  28 /*
  29  * The code space is broken into chunks, to make for efficient
  30  * allocation of large amounts. Each chunk is an array of vvp_code_s
  31  * structures, with the last opcode loaded with an of_CHUNK_LINK
  32  * instruction to branch to the next chunk. This handles the case
  33  * where the program counter steps off the end of a chunk.
  34  */
  35 const unsigned code_chunk_size = 1024;
  36
  37 static struct vvp_code_s *first_chunk = 0;
  38 static struct vvp_code_s *current_chunk = 0;
  39 static unsigned current_within_chunk = 0;
  40
  41 /*
  42  * This initializes the code space. It sets up the first code chunk,
  43  * and places at address 0 a ZOMBIE instruction.
  44  */
  45 void codespace_init(void)
  46 {
  47       assert(current_chunk == 0);
  48       first_chunk = new struct vvp_code_s [code_chunk_size];
  49       current_chunk = first_chunk;
  50
  51       current_chunk[0].opcode = &of_ZOMBIE;
  52
  53       current_chunk[code_chunk_size-1].opcode = &of_CHUNK_LINK;
  54       current_chunk[code_chunk_size-1].cptr = 0;
  55
  56       current_within_chunk = 1;
  57
  58       count_opcodes = 0;
  59       size_opcodes += code_chunk_size * sizeof (struct vvp_code_s);
  60 }
  61
  62 vvp_code_t codespace_next(void)
  63 {
  64       if (current_within_chunk == (code_chunk_size-1)) {
  65             current_chunk[code_chunk_size-1].cptr
  66                   = new struct vvp_code_s [code_chunk_size];
  67             current_chunk = current_chunk[code_chunk_size-1].cptr;
  68
  69               /* Put a link opcode on the end of the chunk. */
  70             current_chunk[code_chunk_size-1].opcode = &of_CHUNK_LINK;
  71             current_chunk[code_chunk_size-1].cptr   = 0;
  72
  73             current_within_chunk = 0;
  74
  75             size_opcodes += code_chunk_size * sizeof (struct vvp_code_s);
  76       }
  77
  78       vvp_code_t res = current_chunk + current_within_chunk;
  79       return res;
  80 }
  81
  82 vvp_code_t codespace_allocate(void)
  83 {
  84       vvp_code_t res = codespace_next();
  85       current_within_chunk += 1;
  86       count_opcodes += 1;
  87
  88       memset(res, 0, sizeof(*res));
  89
  90       return res;
  91 }
  92
  93 vvp_code_t codespace_null(void)
  94 {
  95       return first_chunk + 0;
  96 }
  97
  98 /*
  99  * $Log: codes.cc,v $
 100  * Revision 1.14  2003/08/01 00:58:03  steve
 101  *  Initialize allocated memory.
 102  *
 103  * Revision 1.13  2003/07/03 20:03:36  steve
 104  *  Remove the vvp_cpoint_t indirect code pointer.
 105  *
 106  * Revision 1.12  2002/08/12 01:35:07  steve
 107  *  conditional ident string using autoconfig.
 108  *
 109  * Revision 1.11  2002/07/05 03:46:43  steve
 110  *  Track opcode memory space.
 111  *
 112  * Revision 1.10  2002/07/05 02:50:58  steve
 113  *  Remove the vpi object symbol table after compile.
 114  */
 115