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#define CS_SYSDEF_PROVIDE_HARDWARE_MMIO 1
#include "cssysdef.h"
#include "csutil/mmapio.h"
csMemoryMappedIO::csMemoryMappedIO(unsigned _block_size, char *filename):
block_size(_block_size)
{
valid_mmio_object = MemoryMapFile(&platform, filename);
}
csMemoryMappedIO::~csMemoryMappedIO()
{
UnMemoryMapFile(&platform);
}
/////////////////////////////////////////// Software Support for Memory Mapping ///////////////////////////////////
#ifndef CS_HAS_MEMORY_MAPPED_IO
bool
csMemoryMappedIO::MemoryMapFile(mmioInfo *_platform, char *filename)
{
// Clear the page map
page_map = NULL;
// Initialize cache management variables
cache_block_size = csmmioDefaultCacheBlockSize;
cache_max_size = csmmioDefaultCacheSize;
cache_block_count=0;
// Initialize the cache so that all buckets have at least one block
unsigned i;
for(i=0; i<csmmioDefaultHashSize; ++i)
{
CacheBlock *cp=new CacheBlock;
++cache_block_count;
// Initialize it
cp->data = new unsigned char[block_size * cache_block_size];
// Set young so that it can be used again.
cp->age=0;
// This is the least likely page value.
cp->page=0xffffffff;
// Nothing next
cp->next=0;
cache[i] = cp;
}
#ifdef CS_DEBUG
hits=0;
misses=0;
#endif
if ((_platform->hMappedFile=fopen(filename, "rb")) == NULL)
{
return false;
}
else
{
// Create a page map with one bit per cache block.
page_map = new csBitArray(_platform->file_size/cache_block_size);
// Clear all of it's bits
page_map->Clear();
// Set that we're good to go.
return true;
}
}
void
csMemoryMappedIO::UnMemoryMapFile(mmioInfo *_platform)
{
if (_platform->hMappedFile)
fclose(_platform->hMappedFile);
if (page_map)
delete page_map;
unsigned int i;
CacheBlock *cp, *np;
// Free all allocated memory.
for(i=0; i<csmmioDefaultHashSize; ++i)
{
cp=cache[i];
while(cp)
{
np=cp->next;
delete [] cp->data;
delete cp;
cp=np;
}
}
}
void
csMemoryMappedIO::CachePage(unsigned int page)
{
unsigned int bucket = page % csmmioDefaultHashSize;
CacheBlock *cp;
if (cache_block_count < cache_max_size)
{
cp = new CacheBlock;
++cache_block_count;
// Insert it into the bucket.
cp->next=cache[bucket];
cache[bucket]=cp;
// Initialize it
assert((cp->data = new unsigned char[block_size * cache_block_size])!=NULL);
}
else
{
CacheBlock *block;
// Find the least used block in this bucket.
cp=cache[bucket];
block=cp->next;
while(block)
{
if (block->age < cp->age)
cp=block;
block=block->next;
}
// Unmark this page as allocated
if (cp->page!=0xffffffff) page_map->ClearBit(cp->page);
}
// Get the data for it.
cp->offset=page*cache_block_size;
cp->page=page;
cp->age=0;
// Mark this page as allocated
page_map->SetBit(page);
// Read the page from the file
fseek(platform.hMappedFile, page*cache_block_size*block_size, SEEK_SET);
fread(cp->data, block_size, cache_block_size, platform.hMappedFile);
}
#endif
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