source: sbliveos2/trunk/sblive/emuadxmg.c

/* $Id: emuadxmg.c 142 2000-04-23 14:55:46Z ktk $ */


/*     
 **********************************************************************
 *     emuadxmg.c - Address space manager for emu10k1 driver 
 *     Copyright 1999, 2000 Creative Labs, Inc. 
 * 
 ********************************************************************** 
 * 
 *     Date                 Author          Summary of changes 
 *     ----                 ------          ------------------ 
 *     October 20, 1999     Bertrand Lee    base code release 
 * 
 ********************************************************************** 
 * 
 *     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; if not, write to the Free 
 *     Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, 
 *     USA. 
 * 
 ********************************************************************** 
 */

#include "hwaccess.h"

/* Allocates emu address space */

int emu10k1_addxmgr_alloc(u32 size, struct emu10k1_card *card)
{
        u16 *pagetable = card->emupagetable;
        u16 index = 0;
        u16 numpages;
        unsigned long flags;

        /* Convert bytes to pages */
        numpages = (size / EMUPAGESIZE) + ((size % EMUPAGESIZE) ? 1 : 0);

        while (index < (MAXPAGES - RESERVED - 1)) {
                if (pagetable[index] & 0x8000) {
                        /* This block of pages is in use, jump to the start of the next block. */
                        index += (pagetable[index] & 0x7fff);
                } else {
                        /* Found free block */
                        if (pagetable[index] >= numpages) {
                                spin_lock_irqsave(&card->lock, flags);

                                /* Block is large enough */

                                /* If free block is larger than the block requested
                                 * then adjust the size of the block remaining */
                                if (pagetable[index] > numpages)
                                        pagetable[index + numpages] = pagetable[index] - numpages;

                                pagetable[index] = (numpages | 0x8000); /* Mark block as used */

                                spin_unlock_irqrestore(&card->lock, flags);

                                return index;
                        } else {
                                /* Block too small, jump to the start of the next block */
                                index += pagetable[index];
                        }
                }
        }

        return -1;
}

/* Frees a previously allocated emu address space. */

void emu10k1_addxmgr_free(struct emu10k1_card *card, int index)
{
        u16 *pagetable = card->emupagetable;
        u16 origsize = 0;
        unsigned long flags;

        spin_lock_irqsave(&card->lock, flags);

        if (pagetable[index] & 0x8000) {
                /* Block is allocated - mark block as free */
                origsize = pagetable[index] & 0x7fff;
                pagetable[index] = origsize;

                /* If next block is free, we concat both blocks */
                if (!(pagetable[index + origsize] & 0x8000))
                        pagetable[index] += pagetable[index + origsize] & 0x7fff;
        }

        spin_unlock_irqrestore(&card->lock, flags);

        return;
}