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/*
* Really really *really* Q&D malloc() and free() implementations
* just to get going. Don't ever let anyone see this shit. :^)
*/
#include "types.h"
#include "kmalloc.h"
#include "StdLib.h"
#include "i386.h"
#include "VGA.h"
#include "system.h"
#include "Assertions.h"
#define SANITIZE_KMALLOC
typedef struct
{
DWORD start;
DWORD nchunk;
} PACKED allocation_t;
#define CHUNK_SIZE 128
#define POOL_SIZE (1024 * 1024)
#define BASE_PHYS 0x200000
PRIVATE BYTE alloc_map[POOL_SIZE / CHUNK_SIZE / 8];
volatile DWORD sum_alloc = 0;
volatile DWORD sum_free = POOL_SIZE;
bool is_kmalloc_address(void* ptr)
{
return ptr >= (void*)BASE_PHYS && ptr <= ((void*)BASE_PHYS + POOL_SIZE);
}
PUBLIC void
kmalloc_init()
{
memset( &alloc_map, 0, sizeof(alloc_map) );
memset( (void *)BASE_PHYS, 0, POOL_SIZE );
sum_alloc = 0;
sum_free = POOL_SIZE;
}
PUBLIC void *
kmalloc( DWORD size )
{
InterruptDisabler disabler;
DWORD chunks_needed, chunks_here, first_chunk;
DWORD real_size;
DWORD i, j, k;
/* We need space for the allocation_t structure at the head of the block. */
real_size = size + sizeof(allocation_t);
if (sum_free < real_size) {
kprintf("kmalloc(): PANIC! Out of memory (sucks, dude)\nsum_free=%u, real_size=%x\n", sum_free, real_size);
HANG;
return 0L;
}
chunks_needed = real_size / CHUNK_SIZE;
if( real_size % CHUNK_SIZE )
chunks_needed++;
chunks_here = 0;
first_chunk = 0;
for( i = 0; i < (POOL_SIZE / CHUNK_SIZE / 8); ++i )
{
for( j = 0; j < 8; ++j )
{
if( !(alloc_map[i] & (1<<j)) )
{
if( chunks_here == 0 )
{
/* Mark where potential allocation starts. */
first_chunk = i * 8 + j;
}
chunks_here++;
if( chunks_here == chunks_needed )
{
auto* a = (allocation_t *)(BASE_PHYS + (first_chunk * CHUNK_SIZE));
BYTE *ptr = (BYTE *)a;
ptr += sizeof(allocation_t);
a->nchunk = chunks_needed;
a->start = first_chunk;
for( k = first_chunk; k < (first_chunk + chunks_needed); ++k )
{
alloc_map[k / 8] |= 1 << (k % 8);
}
sum_alloc += a->nchunk * CHUNK_SIZE;
sum_free -= a->nchunk * CHUNK_SIZE;
#ifdef SANITIZE_KMALLOC
memset(ptr, 0xbb, (a->nchunk * CHUNK_SIZE) - sizeof(allocation_t));
#endif
return ptr;
}
}
else
{
/* This is in use, so restart chunks_here counter. */
chunks_here = 0;
}
}
}
kprintf("kmalloc(): PANIC! Out of memory (no suitable block for size %u)\n", size);
HANG;
return nullptr;
}
PUBLIC void
kfree( void *ptr )
{
if( !ptr )
return;
InterruptDisabler disabler;
allocation_t *a = (allocation_t *)((((BYTE *)ptr) - sizeof(allocation_t)));
#if 0
DWORD hdr = (DWORD)a;
DWORD mhdr = hdr & ~0x7;
kprintf("hdr / mhdr %p / %p\n", hdr, mhdr);
ASSERT(hdr == mhdr);
#endif
for (DWORD k = a->start; k < (a->start + a->nchunk); ++k) {
alloc_map[k / 8] &= ~(1 << (k % 8));
}
sum_alloc -= a->nchunk * CHUNK_SIZE;
sum_free += a->nchunk * CHUNK_SIZE;
#ifdef SANITIZE_KMALLOC
memset(a, 0xaa, a->nchunk * CHUNK_SIZE);
#endif
}
void* operator new(unsigned int size)
{
return kmalloc(size);
}
void* operator new[](unsigned int size)
{
return kmalloc(size);
}
void operator delete(void* ptr)
{
return kfree(ptr);
}
void operator delete[](void* ptr)
{
return kfree(ptr);
}
void operator delete(void* ptr, unsigned int)
{
return kfree(ptr);
}
void operator delete[](void* ptr, unsigned int)
{
return kfree(ptr);
}
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