forked from KolibriOS/kolibrios
1025 lines
28 KiB
NASM
1025 lines
28 KiB
NASM
; Copyright (c) 2008-2009, diamond
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; All rights reserved.
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;
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; Redistribution and use in source and binary forms, with or without
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; modification, are permitted provided that the following conditions are met:
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; * Redistributions of source code must retain the above copyright
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; notice, this list of conditions and the following disclaimer.
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; * Redistributions in binary form must reproduce the above copyright
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; notice, this list of conditions and the following disclaimer in the
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; documentation and/or other materials provided with the distribution.
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; * Neither the name of the <organization> nor the
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; names of its contributors may be used to endorse or promote products
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; derived from this software without specific prior written permission.
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;
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; THIS SOFTWARE IS PROVIDED BY Alexey Teplov aka <Lrz> ''AS IS'' AND ANY
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; EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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; WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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; DISCLAIMED. IN NO EVENT SHALL <copyright holder> BE LIABLE FOR ANY
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; DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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; (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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; ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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;*****************************************************************************
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jmp far 0:real_start
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; special text
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org $+0x7C00
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real_start:
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; initialize
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xor ax, ax
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mov ss, ax
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mov sp, 0x7C00
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mov ds, ax
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mov es, ax
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cld
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sti
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mov [bootdrive], dl
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; check LBA support
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mov ah, 41h
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mov bx, 55AAh
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int 13h
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mov si, aNoLBA
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jc err_
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cmp bx, 0AA55h
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jnz err_
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test cl, 1
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jz err_
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; get file system information
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; scan for Primary Volume Descriptor
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db 66h
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push 10h-1
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pop eax
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pvd_scan_loop:
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mov cx, 1
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inc eax
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mov bx, 0x1000
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call read_sectors
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jnc @f
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fatal_read_err:
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mov si, aReadError
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err_:
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call out_string
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mov si, aPressAnyKey
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call out_string
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xor ax, ax
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int 16h
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int 18h
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jmp $
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@@:
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push ds
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pop es
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cmp word [bx+1], 'CD'
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jnz pvd_scan_loop
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cmp word [bx+3], '00'
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jnz pvd_scan_loop
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cmp byte [bx+5], '1'
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jnz pvd_scan_loop
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; we have found ISO9660 descriptor, look for type
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cmp byte [bx], 1 ; Primary Volume Descriptor?
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jz pvd_found
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cmp byte [bx], 0xFF ; Volume Descriptor Set Terminator?
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jnz pvd_scan_loop
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; Volume Descriptor Set Terminator reached, no PVD found - fatal error
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mov si, no_pvd
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jmp err_
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pvd_found:
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add bx, 80h
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mov ax, [bx]
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mov [lb_size], ax
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; calculate number of logical blocks in one sector
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mov ax, 800h
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cwd
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div word [bx]
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mov [lb_per_sec], ax
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; get location of root directory
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mov di, root_location
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movzx eax, byte [bx+1Dh]
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add eax, [bx+1Eh]
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stosd
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; get memory size
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int 12h
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mov si, nomem_str
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cmp ax, 71000h / 400h
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jb err_
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shr ax, 1
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sub ax, 60000h / 800h
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mov [size_rest], ax
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mov [free_ptr], 60000h / 800h
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; load path table
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; if size > 62K => it's very strange, avoid using it
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; if size > (size of cache)/2 => avoid using it too
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mov ecx, [bx+4]
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cmp ecx, 0x10000 - 0x800
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ja nopathtable
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shr ax, 1
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cmp ax, 0x20
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jae @f
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shl ax, 11
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cmp cx, ax
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ja nopathtable
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@@:
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; size is ok, try to load it
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mov [pathtable_size], cx
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mov eax, [bx+12]
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xor edx, edx
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div dword [lb_per_sec]
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imul dx, [bx]
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mov [pathtable_start], dx
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add cx, dx
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call cx_to_sectors
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xor bx, bx
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push 6000h
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pop es
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call read_sectors
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jc nopathtable
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; path table has been loaded
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inc [use_path_table]
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sub [size_rest], cx
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add [free_ptr], cx
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nopathtable:
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; init cache
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mov ax, [size_rest]
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mov [cache_size], ax
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mov ax, [free_ptr]
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mov [cache_start], ax
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; load secondary loader
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mov di, secondary_loader_info
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call load_file
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test bx, bx
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jnz noloader
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; set registers for secondary loader
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mov ah, [bootdrive]
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mov al, 'c'
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mov bx, 'is'
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mov si, callback
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jmp far [si-callback+secondary_loader_info] ; jump to 1000:0000
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noloader:
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mov si, aKernelNotFound
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jmp err_
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read_sectors:
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; es:bx = pointer to data
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; eax = first sector
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; cx = number of sectors
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pushad
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push ds
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do_read_sectors:
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push ax
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push cx
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cmp cx, 0x7F
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jbe @f
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mov cx, 0x7F
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@@:
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; create disk address packet on the stack
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; dq starting LBA
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db 66h
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push 0
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push eax
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; dd buffer
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push es
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push bx
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; dw number of blocks to transfer (no more than 0x7F)
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push cx
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; dw packet size in bytes
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push 10h
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; issue BIOS call
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push ss
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pop ds
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mov si, sp
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mov dl, [cs:bootdrive]
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mov ah, 42h
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int 13h
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jc diskreaderr
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; restore stack
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add sp, 10h
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; increase current sector & buffer; decrease number of sectors
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movzx esi, cx
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mov ax, es
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shl cx, 7
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add ax, cx
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mov es, ax
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pop cx
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pop ax
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add eax, esi
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sub cx, si
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jnz do_read_sectors
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pop ds
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popad
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ret
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diskreaderr:
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add sp, 10h + 2*2
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pop ds
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popad
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stc
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out_string.ret:
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ret
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out_string:
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; in: ds:si -> ASCIIZ string
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lodsb
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test al, al
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jz .ret
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mov ah, 0Eh
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mov bx, 7
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int 10h
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jmp out_string
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aNoLBA db 'The drive does not support LBA!',0
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aReadError db 'Read error',0
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no_pvd db 'Primary Volume Descriptor not found!',0
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nomem_str db 'No memory',0
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aPressAnyKey db 13,10,'Press any key...',13,10,0
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load_file:
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; in: ds:di -> information structure
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; dw:dw address
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; dw limit in 4Kb blocks (0x1000 bytes) (must be non-zero and not greater than 0x100)
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; ASCIIZ name
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; out: bx = status: bx=0 - ok, bx=1 - file is too big, only part of file was loaded, bx=2 - file not found
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; out: dx:ax = file size (0xFFFFFFFF if file not found)
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; parse path to the file
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lea si, [di+6]
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mov eax, [cs:root_location]
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cmp [cs:use_path_table], 0
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jz parse_dir
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; scan for path in path table
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push di
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push 6000h
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pop es
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mov di, [cs:pathtable_start] ; es:di = pointer to current entry in path table
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mov dx, 1 ; dx = number of current entry in path table, start from 1
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mov cx, [cs:pathtable_size]
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pathtable_newparent:
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mov bx, dx ; bx = number of current parent in path table: root = 1
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scan_path_table_e:
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call is_last_component
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jnc path_table_scanned
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scan_path_table_i:
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cmp word [es:di+6], bx
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jb .next
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ja path_table_notfound
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call test_filename1
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jc .next
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@@:
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lodsb
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cmp al, '/'
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jnz @b
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jmp pathtable_newparent
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.next:
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; go to next entry
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inc dx
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movzx ax, byte [es:di]
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add ax, 8+1
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and al, not 1
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add di, ax
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sub cx, ax
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ja scan_path_table_i
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path_table_notfound:
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pop di
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mov ax, -1
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mov dx, ax
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mov bx, 2 ; file not found
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ret
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path_table_scanned:
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movzx eax, byte [es:di+1]
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add eax, [es:di+2]
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pop di
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parse_dir:
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; eax = logical block, ds:di -> information structure, ds:si -> file name
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; was the folder already read?
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push di ds
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push cs
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pop ds
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mov [cur_desc_end], 2000h
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mov bx, cachelist
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.scan1:
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mov bx, [bx+2]
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cmp bx, cachelist
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jz .notfound
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cmp [bx+4], eax
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jnz .scan1
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.found:
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; yes; delete this item from the list (the following code will append this item to the tail)
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mov di, [bx]
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push word [bx+2]
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pop word [di+2]
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mov di, [bx+2]
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push word [bx]
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pop word [di]
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mov di, bx
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jmp .scan
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.notfound:
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; no; load first sector of the folder to get its size
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push eax
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push si
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mov si, 1
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call load_phys_sector_for_lb_force
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mov bx, si
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pop si
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pop eax
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jnc @f
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; read error - return
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.readerr:
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pop ds
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.readerr2:
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pop di
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mov ax, -1
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mov dx, ax
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mov bx, 3
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ret
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@@:
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; first item of the folder describes the folder itself
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; do not cache too big folders: size < 64K and size <= (total cache size)/2
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cmp word [bx+12], 0
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jnz .nocache
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mov cx, [cache_size] ; cx = cache size in sectors
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shr cx, 1 ; cx = (cache size)/2
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cmp cx, 0x20
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jae @f
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shl cx, 11
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cmp [bx+10], cx
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ja .nocache
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@@:
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; we want to cache this folder; get space for it
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mov cx, [bx+10]
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call cx_to_sectors
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jnz .yescache
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.nocache:
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push dword [bx+10]
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pop dword [cur_nocache_len]
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call lb_to_sector
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push ds
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pop es
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pop ds
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.nocache_loop:
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push eax
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mov dx, 1800h
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call scan_for_filename_in_sector
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mov cx, dx
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pop eax
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jnc .j_scandone
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sub cx, bx
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sub word [es:cur_nocache_len], cx
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sbb word [es:cur_nocache_len+2], 0
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jb .j_scandone
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ja @f
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cmp word [es:cur_nocache_len], 0
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jz .j_scandone
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@@:
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mov cx, 1
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inc eax
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push es
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mov bx, 1000h
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call read_sectors
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pop es
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jc .readerr2
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jmp .nocache_loop
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.j_scandone:
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jmp .scandone
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.yescache:
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push bx
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mov bx, [cachelist.head]
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.freeloop:
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cmp cx, [size_rest]
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jbe .sizeok
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@@:
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; if we are here: there is not enough free space, so we must delete old folders' data
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; N.B. We know that after deleting some folders the space will be available (size <= (total cache size)/2).
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; one loop iteration: delete data of one folder
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pusha
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mov dx, [bx+10]
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mov es, dx ; es = segment of folder data to be deleted
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xor di, di
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mov ax, [bx+8]
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add ax, 0x7FF
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rcr ax, 1
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shr ax, 10
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push ax
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shl ax, 11-4 ; get number of paragraphs in folder data to be deleted
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mov cx, [cache_size]
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add cx, [cache_start]
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push ds
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push ax
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add ax, dx
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mov ds, ax
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pop ax
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shl cx, 11-4
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sub cx, dx ; cx = number of paragraphs to be moved
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push si
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xor si, si
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; move cx paragraphs from ds:si to es:di to get free space in the end of cache
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@@:
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sub cx, 1000h
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jbe @f
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push cx
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mov cx, 8000h
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rep movsw
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mov cx, ds
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add cx, 1000h
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mov ds, cx
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mov cx, es
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add cx, 1000h
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mov es, cx
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pop cx
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jmp @b
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@@:
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add cx, 1000h
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shl cx, 3
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rep movsw
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pop si
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pop ds
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; correct positions in cache for existing items
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mov cx, 80h
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mov di, 8400h
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.correct:
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cmp [di+10], dx
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jbe @f
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sub [di+10], ax
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@@:
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add di, 12
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loop .correct
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; some additional space is free now
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pop ax
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add [size_rest], ax
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sub [free_ptr], ax
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; add cache item to the list of free items
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mov dx, [bx]
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mov ax, [free_cache_item]
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mov [bx], ax
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mov [free_cache_item], bx
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mov bx, dx
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; current iteration done
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popa
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jmp .freeloop
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.sizeok:
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mov [cachelist.head], bx
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mov word [bx+2], cachelist
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; allocate new item in cache
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mov di, [free_cache_item]
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test di, di
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jz .nofree
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push word [di]
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pop [free_cache_item]
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jmp @f
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.nofree:
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mov di, [last_cache_item]
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add [last_cache_item], 12
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@@:
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pop bx
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push si di
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; mov [di+4], eax ; start of folder
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scasd
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stosd
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push ax
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mov ax, [free_ptr]
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shl ax, 11-4
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mov [di+10-8], ax
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mov es, ax
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pop ax
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add [free_ptr], cx
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sub [size_rest], cx
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; read folder data
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; first sector is already in memory, 0000:bx
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pusha
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mov cx, [bx+10]
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mov [di+8-8], cx ; folder size in bytes
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mov si, bx
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xor di, di
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mov cx, 0x1800
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sub cx, si
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rep movsb
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pop ax
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push di
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popa
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; read rest of folder
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mov esi, dword [lb_per_sec]
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add eax, esi
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dec si
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not si
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and ax, si
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mov si, word [bx+10]
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mov bx, di
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pop di
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sub si, bx
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jbe @f
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mov [cur_limit], esi
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call read_many_bytes
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pop si
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jnc .scan
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jmp .readerr
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@@:
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pop si
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.scan:
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; now we have required cache item; append it to the end of list
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mov bx, [cachelist.tail]
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mov [cachelist.tail], di
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mov [di+2], bx
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mov word [di], cachelist
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mov [bx], di
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; scan for given filename
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mov es, [di+10]
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mov dx, [di+8]
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pop ds
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xor bx, bx
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call scan_for_filename_in_sector
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.scandone:
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push cs
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pop es
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mov bx, 2000h
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cmp bx, [es:cur_desc_end]
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jnz filefound
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j_notfound:
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jmp path_table_notfound
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filefound:
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@@:
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lodsb
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test al, al
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jz @f
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cmp al, '/'
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jnz @b
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@@:
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mov cl, [es:bx+8]
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test al, al
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jz @f
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; parse next component of file name
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test cl, 2 ; directory?
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jz j_notfound
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mov eax, [es:bx]
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pop di
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jmp parse_dir
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@@:
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test cl, 2 ; directory?
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|
jnz j_notfound ; do not allow read directories as regular files
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; ok, now load the file
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pop di
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les bx, [di]
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call normalize
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|
movzx esi, word [di+4] ; esi = limit in 4K blocks
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|
shl esi, 12 ; esi = limit in bytes
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|
push cs
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pop ds
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mov [cur_limit], esi
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mov di, 2000h
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|
loadloop:
|
|
and [cur_start], 0
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|
.loadnew:
|
|
mov esi, [cur_limit]
|
|
mov eax, [cur_start]
|
|
add esi, eax
|
|
mov [overflow], 1
|
|
sub esi, [di+4]
|
|
jb @f
|
|
xor esi, esi
|
|
dec [overflow]
|
|
@@:
|
|
add esi, [di+4] ; esi = number of bytes to read
|
|
mov [cur_start], esi
|
|
sub esi, eax
|
|
jz .loadcontinue
|
|
xor edx, edx
|
|
div dword [lb_size] ; eax = number of logical blocks to skip,
|
|
mov [first_byte], dx; [first_byte] = number of bytes to skip in 1st block
|
|
cmp byte [di+10], 0
|
|
jnz .interleaved
|
|
add eax, [di]
|
|
; read esi bytes from logical block eax to buffer es:bx
|
|
call read_many_bytes.with_first
|
|
jc .readerr3
|
|
.loadcontinue:
|
|
mov [cur_chunk], di
|
|
add di, 11
|
|
cmp di, [cur_desc_end]
|
|
jae @f
|
|
cmp [cur_limit], 0
|
|
jnz loadloop
|
|
@@:
|
|
mov bx, [overflow]
|
|
.calclen:
|
|
; calculate length of file
|
|
xor ax, ax
|
|
xor dx, dx
|
|
mov di, 2000h
|
|
@@:
|
|
add ax, [di+4]
|
|
adc dx, [di+6]
|
|
add di, 11
|
|
cmp di, [cur_desc_end]
|
|
jb @b
|
|
ret
|
|
.interleaved:
|
|
mov [cur_unit_limit], esi
|
|
push esi
|
|
; skip first blocks
|
|
movzx ecx, byte [di+9] ; Unit Size
|
|
movzx esi, byte [di+10] ; Interleave Gap
|
|
add si, cx
|
|
mov edx, [di]
|
|
@@:
|
|
sub eax, ecx
|
|
jb @f
|
|
add edx, esi
|
|
jmp @b
|
|
@@:
|
|
add ecx, eax ; ecx = number of logical blocks to skip
|
|
lea eax, [ecx+edx] ; eax = first logical block
|
|
pop esi
|
|
.interleaved_loop:
|
|
; get number of bytes in current file unit
|
|
push eax
|
|
movzx eax, byte [di+9]
|
|
sub ax, cx
|
|
imul eax, dword [lb_size]
|
|
cmp eax, esi
|
|
ja .i2
|
|
.i1:
|
|
xchg esi, eax
|
|
.i2:
|
|
pop eax
|
|
sub [cur_unit_limit], esi
|
|
push eax
|
|
; read esi bytes from logical block eax to buffer es:bx
|
|
call read_many_bytes.with_first
|
|
pop eax
|
|
jnc @f
|
|
.readerr3:
|
|
mov bx, 3
|
|
jmp .calclen
|
|
@@:
|
|
mov esi, [cur_unit_limit]
|
|
test esi, esi
|
|
jz .loadcontinue
|
|
movzx ecx, byte [di+9] ; add Unit Size
|
|
add cl, byte [di+10] ; add Interleave Gap
|
|
adc ch, 0
|
|
add eax, ecx
|
|
xor cx, cx
|
|
mov [first_byte], cx
|
|
jmp .interleaved_loop
|
|
|
|
cx_to_sectors:
|
|
add cx, 7FFh
|
|
rcr cx, 1
|
|
shr cx, 10
|
|
ret
|
|
|
|
is_last_component:
|
|
; in: ds:si -> name
|
|
; out: CF set <=> current component is not last (=> folder)
|
|
push si
|
|
@@:
|
|
lodsb
|
|
test al, al
|
|
jz @f
|
|
cmp al, '/'
|
|
jnz @b
|
|
stc
|
|
@@:
|
|
pop si
|
|
ret
|
|
|
|
test_filename1:
|
|
; in: ds:si -> filename, es:di -> path table item
|
|
; out: CF set <=> no match
|
|
pusha
|
|
mov cl, [es:di]
|
|
add di, 8
|
|
jmp test_filename2.start
|
|
test_filename2:
|
|
; in: ds:si -> filename, es:bx -> directory item
|
|
; out: CF set <=> no match
|
|
pusha
|
|
mov cl, [es:bx+32]
|
|
lea di, [bx+33]
|
|
.start:
|
|
mov ch, 0
|
|
@@:
|
|
lodsb
|
|
test al, al
|
|
jz .test1
|
|
cmp al, '/'
|
|
jz .test1
|
|
call toupper
|
|
mov ah, al
|
|
mov al, [es:di]
|
|
call toupper
|
|
inc di
|
|
cmp al, ah
|
|
loopz @b
|
|
jnz .next1
|
|
; if we have reached this point: current name is done
|
|
lodsb
|
|
test al, al
|
|
jz .ret
|
|
cmp al, '/'
|
|
jz .ret
|
|
; if we have reached this point: current name is done, but input name continues
|
|
; so they do not match
|
|
jmp .next1
|
|
.test1:
|
|
; if we have reached this point: input name is done, but current name continues
|
|
; "filename.ext;version" in ISO-9660 represents file "filename.ext"
|
|
; "filename." and "filename.;version" are also possible for "filename"
|
|
cmp byte [es:di], '.'
|
|
jnz @f
|
|
inc di
|
|
dec cx
|
|
jz .ret
|
|
@@:
|
|
cmp byte [es:di], ';'
|
|
jnz .next1
|
|
jmp .ret
|
|
.next1:
|
|
stc
|
|
.ret:
|
|
popa
|
|
ret
|
|
|
|
toupper:
|
|
; in: al=symbol
|
|
; out: al=symbol in uppercase
|
|
cmp al, 'a'
|
|
jb .ret
|
|
cmp al, 'z'
|
|
ja .ret
|
|
sub al, 'a'-'A'
|
|
.ret:
|
|
ret
|
|
|
|
scan_for_filename_in_sector:
|
|
; in: ds:si->filename, es:bx->folder data, dx=limit
|
|
; out: CF=0 if found
|
|
push bx
|
|
.loope:
|
|
push bx
|
|
.loop:
|
|
cmp bx, dx
|
|
jae .notfound
|
|
cmp byte [es:bx], 0
|
|
jz .loopd
|
|
test byte [es:bx+25], 4 ; ignore files with Associated bit
|
|
jnz .next
|
|
call test_filename2
|
|
jc .next
|
|
push ds es di
|
|
push es
|
|
pop ds
|
|
push cs
|
|
pop es
|
|
mov di, [es:cur_desc_end]
|
|
movzx eax, byte [bx+1]
|
|
add eax, [bx+2]
|
|
stosd ; first logical block
|
|
mov eax, [bx+10]
|
|
stosd ; length
|
|
mov al, [bx+25]
|
|
stosb ; flags
|
|
mov ax, [bx+26]
|
|
stosw ; File Unit size, Interleave Gap size
|
|
mov [es:cur_desc_end], di
|
|
cmp di, 3000h
|
|
pop di es ds
|
|
jae .done
|
|
test byte [es:bx+25], 80h
|
|
jz .done
|
|
.next:
|
|
add bl, [es:bx]
|
|
adc bh, 0
|
|
jmp .loop
|
|
.loopd:
|
|
mov ax, bx
|
|
pop bx
|
|
@@:
|
|
add bx, [cs:lb_size]
|
|
jz .done2
|
|
cmp bx, ax
|
|
jb @b
|
|
jmp .loope
|
|
.notfound:
|
|
stc
|
|
.done:
|
|
pop bx
|
|
.done2:
|
|
pop bx
|
|
ret
|
|
|
|
lb_to_sector:
|
|
xor edx, edx
|
|
div dword [lb_per_sec]
|
|
ret
|
|
|
|
load_phys_sector_for_lb_force:
|
|
; in: eax = logical block, ds=0
|
|
; in: si=0 - accept 0 logical blocks, otherwise force read at least 1
|
|
; out: 0000:1000 = physical sector data; si -> logical block
|
|
; out: eax = next physical sector
|
|
; out: CF=1 if read error
|
|
; destroys cx
|
|
; this procedure reads 0-3 or 1-4 logical blocks, up to the end of physical sector
|
|
call lb_to_sector
|
|
or si, dx
|
|
jnz @f
|
|
mov si, 1800h
|
|
jmp .done
|
|
@@:
|
|
mov si, 1000h
|
|
imul dx, [lb_size]
|
|
add si, dx
|
|
mov cx, 1
|
|
push es bx
|
|
push ds
|
|
pop es
|
|
mov bx, 1000h
|
|
call read_sectors
|
|
pop bx es
|
|
inc eax
|
|
.done:
|
|
ret
|
|
|
|
normalize:
|
|
; in: es:bx = far pointer
|
|
; out: es:bx = normalized pointer (i.e. 0 <= bx < 0x10)
|
|
push ax bx
|
|
mov ax, es
|
|
shr bx, 4
|
|
add ax, bx
|
|
mov es, ax
|
|
pop bx ax
|
|
and bx, 0x0F
|
|
ret
|
|
|
|
read_many_bytes:
|
|
and [first_byte], 0
|
|
read_many_bytes.with_first:
|
|
; read esi bytes from logical block dx:ax to buffer es:bx
|
|
; out: CF=1 <=> disk error
|
|
push di
|
|
; load first physical sector
|
|
push bx si
|
|
mov si, [first_byte]
|
|
call load_phys_sector_for_lb_force
|
|
jnc @f
|
|
pop si bx
|
|
.ret:
|
|
pop di
|
|
ret
|
|
@@:
|
|
add si, [first_byte]
|
|
mov ecx, 1800h
|
|
sub cx, si
|
|
mov ebx, esi
|
|
pop bx
|
|
sub ebx, ecx
|
|
jnc @f
|
|
add cx, bx
|
|
xor ebx, ebx
|
|
@@:
|
|
pop di
|
|
sub [cur_limit], ecx
|
|
rep movsb
|
|
mov esi, ebx
|
|
mov bx, di
|
|
call normalize
|
|
; load other physical sectors
|
|
; read esi bytes from physical sector eax to buffer es:bx
|
|
test esi, esi
|
|
jz .ret
|
|
push esi
|
|
add esi, 0x7FF
|
|
and si, not 0x7FF
|
|
cmp esi, [cur_limit]
|
|
jbe .okplace
|
|
.noplace:
|
|
sub esi, 800h
|
|
.okplace:
|
|
shr esi, 11 ; si = number of sectors
|
|
mov cx, si
|
|
jz @f
|
|
call read_sectors
|
|
@@:
|
|
pop esi
|
|
jc .ret
|
|
movzx ecx, cx
|
|
add eax, ecx
|
|
shl ecx, 11
|
|
sub [cur_limit], ecx
|
|
sub esi, ecx
|
|
jc .big
|
|
jz .nopost
|
|
push bx es
|
|
push ds
|
|
pop es
|
|
mov bx, 1000h
|
|
mov cx, 1
|
|
call read_sectors
|
|
pop es di
|
|
jc .ret2
|
|
mov cx, si
|
|
mov si, 1000h
|
|
sub word [cur_limit], cx
|
|
sbb word [cur_limit+2], 0
|
|
rep movsb
|
|
mov bx, di
|
|
call normalize
|
|
.nopost:
|
|
clc
|
|
.ret2:
|
|
pop di
|
|
ret
|
|
.big:
|
|
mov ax, es
|
|
sub ax, 80h
|
|
mov es, ax
|
|
add bx, 800h
|
|
add bx, si
|
|
call normalize
|
|
sub [cur_limit], esi
|
|
jmp .nopost
|
|
|
|
; Callback function for secondary loader
|
|
callback:
|
|
; in: ax = function number; only function 1 is defined for now
|
|
dec ax
|
|
jz callback_readfile
|
|
dec ax
|
|
jz callback_continueread
|
|
stc ; unsupported function
|
|
retf
|
|
|
|
callback_readfile:
|
|
; function 1: read file
|
|
; in: ds:di -> information structure
|
|
; dw:dw address
|
|
; dw limit in 4Kb blocks (0x1000 bytes) (must be non-zero and not greater than 0x100)
|
|
; ASCIIZ name
|
|
; out: bx=0 - ok, bx=1 - file is too big, only part of file was loaded, bx=2 - file not found, bx=3 - read error
|
|
; out: dx:ax = file size (0xFFFFFFFF if file was not found)
|
|
call load_file
|
|
clc ; function is supported
|
|
retf
|
|
|
|
callback_continueread:
|
|
; function 2: continue to read file
|
|
; in: ds:di -> information structure
|
|
; dw:dw address
|
|
; dw limit in 4Kb blocks (0x1000 bytes) (must be non-zero and not greater than 0x100)
|
|
; out: bx=0 - ok, bx=1 - file is too big, only part of file was loaded, bx=3 - read error
|
|
; out: dx:ax = file size
|
|
les bx, [di]
|
|
call normalize
|
|
movzx esi, word [di+4] ; si = limit in 4K blocks
|
|
shl esi, 12 ; bp:si = limit in bytes
|
|
push cs
|
|
pop ds
|
|
mov [cur_limit], esi
|
|
mov di, [cur_chunk]
|
|
call loadloop.loadnew
|
|
clc ; function is supported
|
|
retf
|
|
|
|
secondary_loader_info:
|
|
dw 0, 0x1000
|
|
dw 0x30000 / 0x1000
|
|
db 'kernel.mnt',0
|
|
aKernelNotFound db 'Fatal error: cannot load the kernel',0
|
|
|
|
align 2
|
|
cachelist:
|
|
.head dw cachelist
|
|
.tail dw cachelist
|
|
free_cache_item dw 0
|
|
last_cache_item dw 0x8400
|
|
|
|
use_path_table db 0
|
|
bootdrive db ?
|
|
align 2
|
|
lb_size dw ? ; Logical Block size in bytes
|
|
dw 0 ; to allow access dword [lb_size]
|
|
lb_per_sec dw ? ; Logical Blocks per physical sector
|
|
dw 0 ; to allow access dword [lb_per_sec]
|
|
free_ptr dw ? ; first free block in cache (cache block = sector = 0x800 bytes)
|
|
size_rest dw ? ; free space in cache (in blocks)
|
|
cache_size dw ?
|
|
cache_start dw ?
|
|
pathtable_size dw ?
|
|
pathtable_start dw ?
|
|
root_location dd ?
|
|
cur_desc_end dw ?
|
|
cur_nocache_len dd ?
|
|
cur_limit dd ?
|
|
cur_unit_limit dd ?
|
|
overflow dw ?
|
|
cur_chunk dw ?
|
|
first_byte dw ?
|
|
cur_start dd ?
|
|
|
|
times 83FCh-$ db 0
|
|
db 43h
|
|
; just to make file 2048 bytes long :)
|
|
db 'd' xor 'i' xor 'a' xor 'm' xor 'o' xor 'n' xor 'd'
|
|
|
|
dw 0xAA55 ; this is not required for CD, but to be consistent...
|