diff options
Diffstat (limited to 'ldlinux.asm')
| -rw-r--r-- | ldlinux.asm | 62 |
1 files changed, 7 insertions, 55 deletions
diff --git a/ldlinux.asm b/ldlinux.asm index f54feb3c..b9760680 100644 --- a/ldlinux.asm +++ b/ldlinux.asm @@ -12,10 +12,6 @@ ; from MS-LOSS, and can be especially useful in conjunction with the ; umsdos filesystem. ; -; This file is loaded in stages; first the boot sector at offset 7C00h, -; then the first sector (cluster, really, but we can only assume 1 sector) -; of LDLINUX.SYS at 7E00h and finally the remainder of LDLINUX.SYS at 8000h. -; ; Copyright (C) 1994-2004 H. Peter Anvin ; ; This program is free software; you can redistribute it and/or modify @@ -146,8 +142,6 @@ TotalSectors resd 1 ; Total number of sectors EndSector resd 1 ; Location of filesystem end ClustSize resd 1 ; Bytes/cluster ClustMask resd 1 ; Sectors/cluster - 1 -CachePtrs resw 65536/SECTOR_SIZE ; Cached sector pointers -NextCacheSlot resw 1 ; Next cache slot to occupy CopySuper resb 1 ; Distinguish .bs versus .bss DriveNumber resb 1 ; BIOS drive number ClustShift resb 1 ; Shift count for sectors/cluster @@ -866,6 +860,11 @@ getfattype: rep stosd ; +; Initialize the metadata cache +; + call initcache + +; ; Initialization that does not need to go into the any of the pre-load ; areas ; @@ -1455,55 +1454,7 @@ nextsector: ; getfatsector: add eax,[FAT] ; FAT starting address - ; Fall through - -; -; getcachesector: Check for a particular sector (EAX) in the sector cache, -; and if it is already there, return a pointer in GS:SI -; otherwise load it and return said pointer. -; -; Assumes CS == DS. -; -getcachesector: - push cx - mov si,cache_seg - mov gs,si - mov si,CachePtrs ; Sector cache pointers - mov cx,65536/SECTOR_SIZE -.search: - cmp eax,[si] - jz .hit - add si,4 - loop .search - -.miss: - ; Need to load it. Highly inefficient cache replacement - ; algorithm: Least Recently Written (LRW) - push bx - push es - push gs - pop es - mov bx,[NextCacheSlot] - inc bx - and bx,(1 << (16-SECTOR_SHIFT))-1 - mov [NextCacheSlot],bx - shl bx,2 - mov [CachePtrs+bx],eax - shl bx,SECTOR_SHIFT-2 - mov si,bx - pushad - call getonesec - popad - pop es - pop bx - pop cx - ret - -.hit: ; We have it; get the pointer - sub si,CachePtrs - shl si,SECTOR_SHIFT-2 - pop cx - ret + jmp getcachesector ; ----------------------------------------------------------------------------- ; Common modules @@ -1520,6 +1471,7 @@ getcachesector: %include "graphics.inc" ; VGA graphics %include "highmem.inc" ; High memory sizing %include "strcpy.inc" ; strcpy() +%include "cache.inc" ; Metadata disk cache ; ----------------------------------------------------------------------------- ; Begin data section |