469 lines
9.2 KiB
C
469 lines
9.2 KiB
C
// Emacs style mode select -*- C++ -*-
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//-----------------------------------------------------------------------------
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//
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// $Id:$
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//
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// Copyright (C) 1993-1996 by id Software, Inc.
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//
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// This source is available for distribution and/or modification
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// only under the terms of the DOOM Source Code License as
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// published by id Software. All rights reserved.
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//
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// The source is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// FITNESS FOR A PARTICULAR PURPOSE. See the DOOM Source Code License
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// for more details.
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//
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// $Log:$
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//
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// DESCRIPTION:
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// Zone Memory Allocation. Neat.
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//
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//-----------------------------------------------------------------------------
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static const char
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rcsid[] = "$Id: z_zone.c,v 1.4 1997/02/03 16:47:58 b1 Exp $";
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#include "z_zone.h"
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#include "i_system.h"
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#include "doomdef.h"
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//
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// ZONE MEMORY ALLOCATION
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//
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// There is never any space between memblocks,
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// and there will never be two contiguous free memblocks.
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// The rover can be left pointing at a non-empty block.
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//
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// It is of no value to free a cachable block,
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// because it will get overwritten automatically if needed.
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//
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#define ZONEID 0x1d4a11
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typedef struct
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{
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// total bytes malloced, including header
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int size;
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// start / end cap for linked list
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memblock_t blocklist;
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memblock_t* rover;
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} memzone_t;
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memzone_t* mainzone;
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//
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// Z_ClearZone
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//
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void Z_ClearZone (memzone_t* zone)
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{
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memblock_t* block;
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// set the entire zone to one free block
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zone->blocklist.next =
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zone->blocklist.prev =
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block = (memblock_t *)( (byte *)zone + sizeof(memzone_t) );
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zone->blocklist.user = (void *)zone;
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zone->blocklist.tag = PU_STATIC;
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zone->rover = block;
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block->prev = block->next = &zone->blocklist;
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// NULL indicates a free block.
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block->user = NULL;
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block->size = zone->size - sizeof(memzone_t);
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}
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//
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// Z_Init
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//
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void Z_Init (void)
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{
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memblock_t* block;
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int size;
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mainzone = (memzone_t *)I_ZoneBase (&size);
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mainzone->size = size;
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// set the entire zone to one free block
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mainzone->blocklist.next =
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mainzone->blocklist.prev =
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block = (memblock_t *)( (byte *)mainzone + sizeof(memzone_t) );
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mainzone->blocklist.user = (void *)mainzone;
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mainzone->blocklist.tag = PU_STATIC;
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mainzone->rover = block;
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block->prev = block->next = &mainzone->blocklist;
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// NULL indicates a free block.
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block->user = NULL;
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block->size = mainzone->size - sizeof(memzone_t);
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}
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//
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// Z_Free
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//
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void Z_Free (void* ptr)
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{
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memblock_t* block;
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memblock_t* other;
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block = (memblock_t *) ( (byte *)ptr - sizeof(memblock_t));
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if (block->id != ZONEID)
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I_Error ("Z_Free: freed a pointer without ZONEID");
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if (block->user > (void **)0x100)
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{
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// smaller values are not pointers
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// Note: OS-dependend?
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// clear the user's mark
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*block->user = 0;
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}
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// mark as free
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block->user = NULL;
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block->tag = 0;
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block->id = 0;
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other = block->prev;
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if (!other->user)
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{
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// merge with previous free block
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other->size += block->size;
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other->next = block->next;
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other->next->prev = other;
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if (block == mainzone->rover)
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mainzone->rover = other;
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block = other;
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}
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other = block->next;
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if (!other->user)
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{
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// merge the next free block onto the end
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block->size += other->size;
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block->next = other->next;
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block->next->prev = block;
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if (other == mainzone->rover)
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mainzone->rover = block;
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}
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}
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//
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// Z_Malloc
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// You can pass a NULL user if the tag is < PU_PURGELEVEL.
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//
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#define MINFRAGMENT 64
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void*
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Z_Malloc
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( int size,
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int tag,
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void* user )
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{
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int extra;
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memblock_t* start;
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memblock_t* rover;
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memblock_t* newblock;
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memblock_t* base;
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size = (size + 3) & ~3;
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// scan through the block list,
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// looking for the first free block
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// of sufficient size,
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// throwing out any purgable blocks along the way.
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// account for size of block header
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size += sizeof(memblock_t);
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// if there is a free block behind the rover,
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// back up over them
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base = mainzone->rover;
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if (!base->prev->user)
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base = base->prev;
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rover = base;
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start = base->prev;
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do
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{
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if (rover == start)
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{
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// scanned all the way around the list
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I_Error ("Z_Malloc: failed on allocation of %i bytes", size);
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}
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if (rover->user)
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{
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if (rover->tag < PU_PURGELEVEL)
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{
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// hit a block that can't be purged,
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// so move base past it
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base = rover = rover->next;
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}
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else
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{
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// free the rover block (adding the size to base)
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// the rover can be the base block
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base = base->prev;
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Z_Free ((byte *)rover+sizeof(memblock_t));
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base = base->next;
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rover = base->next;
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}
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}
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else
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rover = rover->next;
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} while (base->user || base->size < size);
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// found a block big enough
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extra = base->size - size;
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if (extra > MINFRAGMENT)
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{
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// there will be a free fragment after the allocated block
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newblock = (memblock_t *) ((byte *)base + size );
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newblock->size = extra;
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// NULL indicates free block.
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newblock->user = NULL;
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newblock->tag = 0;
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newblock->prev = base;
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newblock->next = base->next;
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newblock->next->prev = newblock;
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base->next = newblock;
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base->size = size;
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}
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if (user)
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{
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// mark as an in use block
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base->user = user;
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*(void **)user = (void *) ((byte *)base + sizeof(memblock_t));
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}
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else
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{
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if (tag >= PU_PURGELEVEL)
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I_Error ("Z_Malloc: an owner is required for purgable blocks");
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// mark as in use, but unowned
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base->user = (void *)2;
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}
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base->tag = tag;
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// next allocation will start looking here
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mainzone->rover = base->next;
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base->id = ZONEID;
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return (void *) ((byte *)base + sizeof(memblock_t));
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}
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//
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// Z_FreeTags
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//
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void
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Z_FreeTags
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( int lowtag,
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int hightag )
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{
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memblock_t* block;
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memblock_t* next;
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for (block = mainzone->blocklist.next ;
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block != &mainzone->blocklist ;
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block = next)
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{
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// get link before freeing
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next = block->next;
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// free block?
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if (!block->user)
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continue;
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if (block->tag >= lowtag && block->tag <= hightag)
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Z_Free ( (byte *)block+sizeof(memblock_t));
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}
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}
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//
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// Z_DumpHeap
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// Note: TFileDumpHeap( stdout ) ?
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//
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void
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Z_DumpHeap
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( int lowtag,
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int hightag )
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{
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memblock_t* block;
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I_printf ("zone size: %i location: %p\n",
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mainzone->size,mainzone);
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I_printf ("tag range: %i to %i\n",
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lowtag, hightag);
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for (block = mainzone->blocklist.next ; ; block = block->next)
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{
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if (block->tag >= lowtag && block->tag <= hightag)
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I_printf ("block:%p size:%7i user:%p tag:%3i\n",
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block, block->size, block->user, block->tag);
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if (block->next == &mainzone->blocklist)
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{
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// all blocks have been hit
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break;
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}
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if ( (byte *)block + block->size != (byte *)block->next)
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I_printf ("ERROR: block size does not touch the next block\n");
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if ( block->next->prev != block)
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I_printf ("ERROR: next block doesn't have proper back link\n");
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if (!block->user && !block->next->user)
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I_printf ("ERROR: two consecutive free blocks\n");
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}
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}
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#if 0
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//
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// Z_FileDumpHeap
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//
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void Z_FileDumpHeap (FILE* f)
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{
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memblock_t* block;
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fprintf (f,"zone size: %i location: %p\n",mainzone->size,mainzone);
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for (block = mainzone->blocklist.next ; ; block = block->next)
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{
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fprintf (f,"block:%p size:%7i user:%p tag:%3i\n",
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block, block->size, block->user, block->tag);
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if (block->next == &mainzone->blocklist)
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{
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// all blocks have been hit
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break;
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}
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if ( (byte *)block + block->size != (byte *)block->next)
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fprintf (f,"ERROR: block size does not touch the next block\n");
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if ( block->next->prev != block)
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fprintf (f,"ERROR: next block doesn't have proper back link\n");
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if (!block->user && !block->next->user)
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fprintf (f,"ERROR: two consecutive free blocks\n");
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}
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}
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#endif
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//
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// Z_CheckHeap
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//
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void Z_CheckHeap (void)
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{
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memblock_t* block;
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for (block = mainzone->blocklist.next ; ; block = block->next)
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{
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if (block->next == &mainzone->blocklist)
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{
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// all blocks have been hit
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break;
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}
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if ( (byte *)block + block->size != (byte *)block->next)
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I_Error ("Z_CheckHeap: block size does not touch the next block\n");
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if ( block->next->prev != block)
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I_Error ("Z_CheckHeap: next block doesn't have proper back link\n");
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if (!block->user && !block->next->user)
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I_Error ("Z_CheckHeap: two consecutive free blocks\n");
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}
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}
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//
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// Z_ChangeTag
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//
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void
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Z_ChangeTag2
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( void* ptr,
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int tag )
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{
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memblock_t* block;
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block = (memblock_t *) ( (byte *)ptr - sizeof(memblock_t));
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if (block->id != ZONEID)
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I_Error ("Z_ChangeTag: freed a pointer without ZONEID");
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if (tag >= PU_PURGELEVEL && (unsigned)block->user < 0x100)
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I_Error ("Z_ChangeTag: an owner is required for purgable blocks");
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block->tag = tag;
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}
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//
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// Z_FreeMemory
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//
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int Z_FreeMemory (void)
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{
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memblock_t* block;
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int free;
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free = 0;
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for (block = mainzone->blocklist.next ;
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block != &mainzone->blocklist;
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block = block->next)
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{
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if (!block->user || block->tag >= PU_PURGELEVEL)
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free += block->size;
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}
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return free;
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}
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