Import backup from 2003-12-30
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6
kernel.c
6
kernel.c
@ -2,7 +2,7 @@
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//08/13/03 Josh Holtrop
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//Holtrop's Operating System
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//Version: 0.12
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//Modified: 11/12/03
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//Modified: 12/30/03
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#include "k_defines.h" //#DEFINE's for kernel
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@ -68,8 +68,8 @@ void k_init()
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video_drawConsole();
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}
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printf("HOS 0.13 - Kernel Size: %u kb\n", kernel_size()>>10);
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printf("Memory available to OS: %u MB (Bytes: %u)\n", mm_megabytes, mm_totalmem);
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printf("HOS 0.13 - Kernel File Size: %u kb\tData Size: %u bytes\n", kernel_size()>>10, (dword)(&_end)-(dword)(&_code));
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printf("Memory available to OS: %u MB (%u bytes)\n", mm_megabytes, mm_totalmem);
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printf("Free memory: %u bytes (%u pages)\n", mm_freemem(), mm_freemem()>>12);
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dword key = 0;
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245
vmm.c
245
vmm.c
@ -1,10 +1,12 @@
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// vmm.c
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// Author: Josh Holtrop
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// Date: 09/30/03
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// Rewritten from scratch: 12/23/03
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// Modified: 12/30/03
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// This is the initialization procedure for the Virtual Memory Manager
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// It sets up the final page directory/page table setup and maps video memory, if present
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void vmm_init()
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{
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dword *pageTables = (dword *)0xC0104000; //this is the location of the page directory
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@ -31,6 +33,7 @@ void vmm_init()
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}
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// This function initialzes a Heap Entry Block to unused entries linked together
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void vmm_heb_init(HeapEntryBlock *heb)
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{
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int a;
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@ -45,7 +48,7 @@ void vmm_heb_init(HeapEntryBlock *heb)
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}
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// This function maps a virtual address to a physical address using the page directory / page table
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void vmm_map1(dword virt, dword physical)
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{
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dword pde = virt >> 22;
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@ -69,6 +72,7 @@ void vmm_map1(dword virt, dword physical)
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}
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// This function maps a variable number of pages in a row
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void vmm_mapn(dword virt, dword physical, dword n)
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{
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for (; n > 0; n--)
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@ -80,6 +84,7 @@ void vmm_mapn(dword virt, dword physical, dword n)
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}
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// This function removes the virtual address's entry in the page directory / page table
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void vmm_unmap1(dword virt)
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{
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dword *pteptr = (dword *)(0xFFC00000 | ((virt & 0xFFC00000) >> 10) | ((virt & 0x003FF000) >> 10));
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@ -88,6 +93,7 @@ void vmm_unmap1(dword virt)
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}
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// This function removes multiple pages' entries
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void vmm_unmapn(dword virt, dword n)
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{
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for (; n > 0; n--)
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@ -98,39 +104,248 @@ void vmm_unmapn(dword virt, dword n)
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}
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// Virtual Memory allocator function
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void *malloc(dword bytes)
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{
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if (bytes % VMM_MALLOC_GRANULARITY)
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bytes = bytes + VMM_MALLOC_GRANULARITY - (bytes % VMM_MALLOC_GRANULARITY);
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void *attempt = vmm_getFreeChunk(bytes);
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if (attempt)
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return attempt;
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if(vmm_moreCore(bytes))
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return 0; //we could not get any more heap memory
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return vmm_getFreeChunk(bytes);
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}
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// This function returns a pointer if a free chunk of memory exists
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void *vmm_getFreeChunk(dword bytes)
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{
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HeapEntry *he = firstHeapEntry;
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for (;;)
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{
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if ((he->size >= bytes) && (he->attributes = VMM_HE_FREE))
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if (he->attributes == VMM_HE_FREE)
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{
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if (he->size > bytes)
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{
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HeapEntry *nhe = vmm_nextHeapEntry();
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nhe->base = he->base;
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nhe->size = bytes;
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nhe->attributes = VMM_HE_USED;
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he->base += bytes;
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he->size -= bytes;
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return (void *)(nhe->base);
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}
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if (he->size == bytes)
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{
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he->attributes = VMM_HE_USED;
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return (void *)(he->base);
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}
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else
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}
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he = (HeapEntry *)he->link;
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if (!he)
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break;
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}
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return 0;
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}
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// This function coalesces any two adjacent heap entries into one entry
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void vmm_coalesceHeapEntry(HeapEntry *he)
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{
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if (!(he->attributes == VMM_HE_FREE || he->attributes == VMM_HE_HOLE))
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return;
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if (he->size == 0)
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{
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he->attributes = VMM_HE_UNUSED;
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return;
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}
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HeapEntry *hec = firstHeapEntry;
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for (;;)
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{
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if (hec->attributes == he->attributes)
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{
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if ((hec->base + hec->size) == he->base) //hec ends where he begins
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{
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//get the next HeapEntry, save in it the free mem, save in this entry the used mem...
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he->base = hec->base;
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he->size += hec->size;
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hec->attributes = VMM_HE_UNUSED;
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}
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if ((he->base + he->size) == hec->base) //he ends where hec begins
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{
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he->size += hec->size;
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hec->attributes = VMM_HE_UNUSED;
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}
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}
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hec = (HeapEntry *)hec->link;
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if (!hec)
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break;
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}
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}
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// This function retrieves more physical memory for the heap
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int vmm_moreCore(dword bytes)
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{
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dword pages = (bytes >> 12) + 1;
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bytes = pages << 12;
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HeapEntry *he = vmm_getFirstHoleHeapEntry(bytes);
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dword virt = he->base;
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for (; pages > 0; pages--)
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{
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dword phys = (dword)mm_palloc();
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if (!phys)
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return 1;
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vmm_map1(virt, phys);
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virt += 4096;
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}
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if (he->size == bytes)
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{
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he->attributes = VMM_HE_FREE;
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vmm_coalesceHeapEntry(he);
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}
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else
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{
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HeapEntry *nhe = vmm_nextHeapEntry();
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nhe->base = he->base;
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nhe->size = bytes;
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nhe->attributes = VMM_HE_FREE;
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he->base += bytes;
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he->size -= bytes;
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vmm_coalesceHeapEntry(nhe);
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}
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return 0;
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}
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// This function returns the next available heap entry, creates more entries if we are running low
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HeapEntry *vmm_nextHeapEntry()
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{
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if (vmm_heapEntriesLeft() < 10)
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vmm_addHeapEntryBlock();
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return vmm_getFirstUnusedHeapEntry();
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}
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// This function creates a new block (page) of heap entries (256)
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void vmm_addHeapEntryBlock()
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{
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HeapEntry *he = vmm_getFirstHoleHeapEntry(4096);
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HeapEntry *newBlock = vmm_getFirstUnusedHeapEntry();
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dword heb = (dword)mm_palloc();
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vmm_map1(he->base, heb);
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vmm_heb_init((HeapEntryBlock *)he->base);
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HeapEntry *lhe = vmm_getLastHeapEntry();
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if (he->size == 4096)
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{
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he->attributes = VMM_HE_HEB;
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lhe->link = (dword)he->base;
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}
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else
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{
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newBlock->base = he->base;
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newBlock->size = 4096;
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newBlock->attributes = VMM_HE_HEB;
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he->base += 4096;
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he->size -= 4096;
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lhe->link = (dword)newBlock->base;
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}
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return;
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}
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// This function returns the last heap entry in the linked list, useful for setting
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// its link field to point to the first entry of a newly allocated list
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HeapEntry *vmm_getLastHeapEntry()
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{
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HeapEntry *he = firstHeapEntry;
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for (;;)
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{
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if (he->link == 0)
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return he;
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he = (HeapEntry *)he->link;
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}
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}
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// This function returns the first heap entry corresponding to a memory "hole"
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HeapEntry *vmm_getFirstHoleHeapEntry(dword minBytes)
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{
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HeapEntry *he = firstHeapEntry;
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for (;;)
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{
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if ((he->attributes == VMM_HE_HOLE) && (he->size >= minBytes))
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return he;
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he = (HeapEntry *)he->link;
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if (!he)
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break;
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}
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return 0;
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}
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// This function returns the first heap entry that is not being used
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HeapEntry *vmm_getFirstUnusedHeapEntry()
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{
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HeapEntry *he = firstHeapEntry;
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for (;;)
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{
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if (he->attributes == VMM_HE_UNUSED)
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return he;
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he = (HeapEntry *)he->link;
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if (!he)
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break;
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}
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return 0;
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}
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// This function returns the number of heap entries available for use
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dword vmm_heapEntriesLeft()
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{
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HeapEntry *he = firstHeapEntry;
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dword entries = 0;
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for (;;)
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{
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if (he->attributes == VMM_HE_UNUSED)
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entries++;
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he = (HeapEntry *)he->link;
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if (!he)
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break;
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}
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return entries;
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}
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// This function "frees" an area of memory previously allocated with malloc()
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int free(void *ptr)
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{
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HeapEntry *he = vmm_getHeapEntryByBase((dword)ptr);
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if (!he)
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return 1; //a heap entry starting at the given address was not found
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he->attributes = VMM_HE_FREE;
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vmm_coalesceHeapEntry(he);
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return 0;
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}
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// This function scans the heap entry linked list for an entry that begins at the given address
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HeapEntry *vmm_getHeapEntryByBase(dword base)
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{
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HeapEntry *he = firstHeapEntry;
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for (;;)
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{
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if (he->base == base)
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return he;
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he = (HeapEntry *)he->link;
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if (!he)
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break;
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}
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return 0;
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}
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int free(void *ptr)
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{
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}
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15
vmm.h
15
vmm.h
@ -2,7 +2,7 @@
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// Author: Josh Holtrop
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// Date: 09/30/03
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// Rewritten from scratch: 12/23/03
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// Modified: 12/29/03
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// Modified: 12/30/03
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#define VMM_HE_UNUSED 0 //available entry
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@ -11,6 +11,7 @@
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#define VMM_HE_HOLE 3 //a "hole" (unmapped) section of virtual memory
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#define VMM_HE_HEB 4 //HeapEntryBlock
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#define VMM_MALLOC_GRANULARITY 4 //granularity for all memory requests
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typedef struct {
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dword base; //virtual base address
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@ -33,9 +34,19 @@ void vmm_mapn(dword virt, dword physical, dword n);
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void vmm_unmap1(dword virt);
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void vmm_unmapn(dword virt, dword n);
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void vmm_heb_init(HeapEntryBlock *heb);
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void *vmm_getFreeChunk(dword bytes);
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HeapEntry *vmm_nextHeapEntry();
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dword vmm_heapEntriesLeft();
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HeapEntry *vmm_getLastHeapEntry();
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HeapEntry *vmm_getFirstUnusedHeapEntry();
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HeapEntry *vmm_getFirstHoleHeapEntry(dword minBytes);
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void vmm_addHeapEntryBlock();
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int vmm_moreCore(dword bytes);
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void vmm_coalesceHeapEntry(HeapEntry *he);
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HeapEntry *vmm_getHeapEntryByBase(dword base);
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HeapEntry *firstHeapEntry = (HeapEntry *)0xD0000000;
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HeapEntry *firstHeapEntry = (HeapEntry *)0xD0000000; //this is where heap memory starts
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