src/mm.c

   1 /*
   2  * Open Hack'Ware BIOS memory management.
   3  *
   4  * Copyright (c) 2004-2005 Jocelyn Mayer
   5  *
   6  *   This program is free software; you can redistribute it and/or
   7  *   modify it under the terms of the GNU General Public License V2
   8  *   as published by the Free Software Foundation
   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
  20 #include <stdlib.h>
  21 #include "bios.h"
  22
  23 #if 0
  24 static uint8_t *page_bitmap;
  25 static uint32_t memory_size;
  26
  27 static void mark_page_in_use (uint32_t page_nb)
  28 {
  29     uint32_t offset, bit;
  30
  31     offset = page_nb >> 3;
  32     bit = page_nb & 7;
  33     page_bitmap[offset] |= 1 << bit;
  34 }
  35
  36 static void mark_page_free (uint32_t page_nb)
  37 {
  38     uint32_t offset, bit;
  39
  40     offset = page_nb >> 3;
  41     bit = page_nb & 7;
  42     page_bitmap[offset] &= ~(1 << bit);
  43 }
  44
  45 static int is_page_in_use (uint32_t page_nb)
  46 {
  47     uint32_t offset, bit;
  48
  49     offset = page_nb >> 3;
  50     bit = page_nb & 7;
  51
  52     return (page_bitmap[offset] & (~(1 << bit))) != 0;
  53 }
  54
  55 void mm_init (uint32_t memsize)
  56 {
  57     uint32_t page_start, page_ram_start, page, ram_start;
  58     uint32_t nb_pages, bitmap_size;
  59
  60     /* Init bitmap */
  61     ram_start = (uint32_t)(&_ram_start);
  62     ram_start = (ram_start + (1 << 12) - 1) & ~((1 << 12) - 1);
  63     page_bitmap = (void *)ram_start;
  64     nb_pages = (memsize + (1 << 12) - 1) >> 12;
  65     bitmap_size = (nb_pages + 7) >> 3;
  66     /* First mark all pages as free */
  67     memset(page_bitmap, 0, bitmap_size);
  68     /* Mark all pages used by the BIOS as used (code + data + bitmap) */
  69     page_start = (uint32_t)(0x05800000) >> 12; /* TO FIX */
  70     ram_start += bitmap_size;
  71     ram_start = (ram_start + (1 << 12) - 1) & ~((1 << 12) - 1);
  72     page_ram_start = ram_start >> 12;
  73     for (page = page_start; page < page_ram_start; page++)
  74         mark_page_in_use(page);
  75     memory_size = memsize;
  76 }
  77
  78 void *page_get (int nb_pages)
  79 {
  80     uint32_t page_start, page_end, page;
  81     int nb;
  82
  83     page_start = (uint32_t)(0x05800000) >> 12; /* TO FIX */
  84     page_end = memory_size >> 12;
  85     for (page = page_start; page < page_end; ) {
  86         /* Skip all full "blocs" */
  87         for (; page < page_end; page += 8) {
  88             if (page_bitmap[page >> 3] != 0xFF)
  89                 break;
  90         }
  91         for (nb = 0; page < page_end; page++) {
  92             if (!is_page_in_use(page)) {
  93                 nb++;
  94                 if (nb == nb_pages) {
  95                     /* Found ! */
  96                     for (; nb >= 0; nb--, page--)
  97                         mark_page_in_use(page);
  98
  99                     return (void *)(page << 12);
 100                 }
 101             }
 102         }
 103     }
 104
 105     return NULL;
 106 }
 107
 108 void page_put (void *addr, int nb_pages)
 109 {
 110     uint32_t page_start, page_end, page;
 111
 112     page_start = (uint32_t)addr >> 12;
 113     page_end = page_start + nb_pages;
 114     for (page = page_start; page < page_end; page++) {
 115         if (!is_page_in_use(page))
 116             printf("ERROR: page %u has already been freed !\n", page);
 117         mark_page_free(page);
 118     }
 119 }
 120 #else
 121 static uint8_t *page_alloc;
 122
 123 void mm_init (unused uint32_t memsize)
 124 {
 125     uint32_t ram_start;
 126     ram_start = (uint32_t)(&_ram_start);
 127     ram_start = (ram_start + (1 << 12) - 1) & ~((1 << 12) - 1);
 128     page_alloc = (void *)ram_start;
 129 }
 130
 131 void *page_get (unused int nb_pages)
 132 {
 133     void *ret;
 134
 135     ret = page_alloc;
 136     page_alloc += nb_pages << 12;
 137     memset(ret, 0, nb_pages << 12);
 138
 139     return ret;
 140 }
 141
 142 void page_put (unused void *addr, unused int nb_pages)
 143 {
 144 }
 145 #endif