ref: 078dd1d6d088aab71c37c0e21fea5cebfe1271a8
dir: /z_zone.c/
// Z_zone.c
#include "h2stdinc.h"
#include "doomdef.h"
/*
==============================================================================
ZONE MEMORY ALLOCATION
There is never any space between memblocks, and there will never be two
contiguous free memblocks.
The rover can be left pointing at a non-empty block
It is of no value to free a cachable block, because it will get overwritten
automatically if needed
==============================================================================
*/
typedef struct
{
int size; // total bytes malloced, including header
memblock_t blocklist; // start / end cap for linked list
memblock_t *rover;
} memzone_t;
static memzone_t *mainzone;
boolean MallocFailureOk;
/*
========================
=
= Z_ClearZone
=
========================
*/
void Z_ClearZone (memzone_t *zone)
{
memblock_t *block;
// set the entire zone to one free block
zone->blocklist.next = zone->blocklist.prev = block =
(memblock_t *)( (byte *)zone + sizeof(memzone_t) );
zone->blocklist.user = (void **)zone;
zone->blocklist.tag = PU_STATIC;
zone->rover = block;
block->prev = block->next = &zone->blocklist;
block->user = NULL; // free block
block->size = zone->size - sizeof(memzone_t);
}
/*
========================
=
= Z_Init
=
========================
*/
void Z_Init (void)
{
memblock_t *block;
int size;
MallocFailureOk = false;
mainzone = (memzone_t *)I_ZoneBase (&size);
mainzone->size = size;
// set the entire zone to one free block
mainzone->blocklist.next = mainzone->blocklist.prev = block =
(memblock_t *)( (byte *)mainzone + sizeof(memzone_t) );
mainzone->blocklist.user = (void **)mainzone;
mainzone->blocklist.tag = PU_STATIC;
mainzone->rover = block;
block->prev = block->next = &mainzone->blocklist;
block->user = NULL; // free block
block->size = mainzone->size - sizeof(memzone_t);
}
/*
========================
=
= Z_Free
=
========================
*/
void Z_Free (void *ptr)
{
memblock_t *block, *other;
block = (memblock_t *) ( (byte *)ptr - sizeof(memblock_t));
if (block->id != ZONEID)
I_Error ("Z_Free: freed a pointer without ZONEID");
if (block->user > (void **)0x100) // smaller values are not pointers
*block->user = 0; // clear the user's mark
block->user = NULL; // mark as free
block->tag = 0;
block->id = 0;
other = block->prev;
if (!other->user)
{ // merge with previous free block
other->size += block->size;
other->next = block->next;
other->next->prev = other;
if (block == mainzone->rover)
mainzone->rover = other;
block = other;
}
other = block->next;
if (!other->user)
{ // merge the next free block onto the end
block->size += other->size;
block->next = other->next;
block->next->prev = block;
if (other == mainzone->rover)
mainzone->rover = block;
}
}
/*
========================
=
= Z_Malloc
=
= You can pass a NULL user if the tag is < PU_PURGELEVEL
========================
*/
#define MINFRAGMENT 64
void *Z_Malloc (int size, int tag, void *user)
{
int extra;
memblock_t *start, *rover, *newblock, *base;
//
// scan through the block list looking for the first free block
// of sufficient size, throwing out any purgable blocks along the way
//
size += sizeof(memblock_t); // account for size of block header
size = (size + 7) & ~7; // align to 8-byte boundary
//
// if there is a free block behind the rover, back up over them
//
base = mainzone->rover;
if (!base->prev->user)
base = base->prev;
rover = base;
start = base->prev;
do
{
if (rover == start) // scaned all the way around the list
{
if (MallocFailureOk == true)
{
return NULL;
}
else
{
I_Error("Z_Malloc: failed on allocation of %i bytes", size);
}
}
if (rover->user)
{
if (rover->tag < PU_PURGELEVEL)
// hit a block that can't be purged, so move base past it
base = rover = rover->next;
else
{
// free the rover block (adding the size to base)
base = base->prev; // the rover can be the base block
Z_Free ((byte *)rover + sizeof(memblock_t));
base = base->next;
rover = base->next;
}
}
else
rover = rover->next;
} while (base->user || base->size < size);
//
// found a block big enough
//
extra = base->size - size;
if (extra > MINFRAGMENT)
{ // there will be a free fragment after the allocated block
newblock = (memblock_t *) ((byte *)base + size);
newblock->size = extra;
newblock->user = NULL; // free block
newblock->tag = 0;
newblock->prev = base;
newblock->next = base->next;
newblock->next->prev = newblock;
base->next = newblock;
base->size = size;
}
if (user)
{
base->user = (void **)user; // mark as an in use block
*(void **)user = (void *) ((byte *)base + sizeof(memblock_t));
}
else
{
if (tag >= PU_PURGELEVEL)
I_Error ("Z_Malloc: an owner is required for purgable blocks");
base->user = (void **) 2; // mark as in use, but unowned
}
base->tag = tag;
mainzone->rover = base->next; // next allocation will start looking here
base->id = ZONEID;
return (void *) ((byte *)base + sizeof(memblock_t));
}
/*
========================
=
= Z_FreeTags
=
========================
*/
void Z_FreeTags (int lowtag, int hightag)
{
memblock_t *block, *next;
for (block = mainzone->blocklist.next ; block != &mainzone->blocklist; block = next)
{
next = block->next; // get link before freeing
if (!block->user)
continue; // free block
if (block->tag >= lowtag && block->tag <= hightag)
Z_Free ( (byte *)block+sizeof(memblock_t));
}
}
/*
========================
=
= Z_DumpHeap
=
========================
*/
void Z_DumpHeap (int lowtag, int hightag)
{
memblock_t *block;
printf ("zone size: %i location: %p\n", mainzone->size,mainzone);
printf ("tag range: %i to %i\n", lowtag, hightag);
for (block = mainzone->blocklist.next ; ; block = block->next)
{
if (block->tag >= lowtag && block->tag <= hightag)
printf ("block:%p size:%7i user:%p tag:%3i\n",
block, block->size, block->user, block->tag);
if (block->next == &mainzone->blocklist)
break; // all blocks have been hit
if ( (byte *)block + block->size != (byte *)block->next)
printf ("ERROR: block size does not touch the next block\n");
if ( block->next->prev != block)
printf ("ERROR: next block doesn't have proper back link\n");
if (!block->user && !block->next->user)
printf ("ERROR: two consecutive free blocks\n");
}
}
/*
========================
=
= Z_FileDumpHeap
=
========================
*/
void Z_FileDumpHeap (FILE *f)
{
memblock_t *block;
fprintf (f, "zone size: %i location: %p\n", mainzone->size, mainzone);
for (block = mainzone->blocklist.next ; ; block = block->next)
{
fprintf (f, "block:%p size:%7i user:%p tag:%3i\n",
block, block->size, block->user, block->tag);
if (block->next == &mainzone->blocklist)
break; // all blocks have been hit
if ( (byte *)block + block->size != (byte *)block->next)
fprintf (f, "ERROR: block size does not touch the next block\n");
if ( block->next->prev != block)
fprintf (f, "ERROR: next block doesn't have proper back link\n");
if (!block->user && !block->next->user)
fprintf (f, "ERROR: two consecutive free blocks\n");
}
}
/*
========================
=
= Z_CheckHeap
=
========================
*/
void Z_CheckHeap (void)
{
memblock_t *block;
for (block = mainzone->blocklist.next ; ; block = block->next)
{
if (block->next == &mainzone->blocklist)
break; // all blocks have been hit
if ( (byte *)block + block->size != (byte *)block->next)
I_Error ("Z_CheckHeap: block size does not touch the next block\n");
if ( block->next->prev != block)
I_Error ("Z_CheckHeap: next block doesn't have proper back link\n");
if (!block->user && !block->next->user)
I_Error ("Z_CheckHeap: two consecutive free blocks\n");
}
}
/*
========================
=
= Z_ChangeTag
=
========================
*/
void Z_ChangeTag2 (void *ptr, int tag)
{
memblock_t *block;
block = (memblock_t *) ( (byte *)ptr - sizeof(memblock_t));
if (block->id != ZONEID)
I_Error ("Z_ChangeTag: freed a pointer without ZONEID");
if (tag >= PU_PURGELEVEL && (uintptr_t)block->user < 0x100)
I_Error ("Z_ChangeTag: an owner is required for purgable blocks");
block->tag = tag;
}
/*
========================
=
= Z_FreeMemory
=
========================
*/
int Z_FreeMemory (void)
{
memblock_t *block;
int freemem;
freemem = 0;
for (block = mainzone->blocklist.next ; block != &mainzone->blocklist; block = block->next)
{
if (!block->user || block->tag >= PU_PURGELEVEL)
freemem += block->size;
}
return freemem;
}