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|
;; -----------------------------------------------------------------------
;;
;; Copyright 1994-2008 H. Peter Anvin - All Rights Reserved
;;
;; This program is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, Inc., 53 Temple Place Ste 330,
;; Boston MA 02111-1307, USA; either version 2 of the License, or
;; (at your option) any later version; incorporated herein by reference.
;;
;; -----------------------------------------------------------------------
;;
;; loadhigh.inc
;;
;; Load a file into high memory
;;
section .text
;
; load_high: loads (the remainder of) a file into high memory.
; This routine prints dots for each 64K transferred, and
; calls abort_check periodically.
;
; The xfer_buf_seg is used as a bounce buffer.
;
; Assumes CS == DS.
;
; The input address (EDI) should be dword aligned, and the final
; stretch is padded with zeroes if necessary.
;
; Inputs: SI = file handle/cluster pointer
; EDI = target address in high memory
; EAX = maximum number of bytes to load
; DX = zero-padding mask (e.g. 0003h for pad to dword)
; BX = subroutine to call at the top of each loop
; (to print status and check for abort)
; MyHighMemSize = maximum load address
;
; Outputs: SI = file handle/cluster pointer
; EBX = first untouched address (not including padding)
; EDI = first untouched address (including padding)
; CF = reached EOF
;
load_high:
push es ; <AAA> ES
mov cx,xfer_buf_seg
mov es,cx
mov [PauseBird],bx
.read_loop:
and si,si ; If SI == 0 then we have end of file
jz .eof
call [PauseBird]
push eax ; <A> Total bytes to transfer
cmp eax,(1 << 16) ; Max 64K in one transfer
jna .size_ok
mov eax,(1 << 16)
.size_ok:
push eax ; <B> Bytes transferred this chunk
add eax,SECTOR_SIZE-1
shr eax,SECTOR_SHIFT ; Convert to sectors
; Now (e)ax contains the number of sectors to get
push edi ; <C> Target buffer
mov cx,ax
xor bx,bx ; ES:0
call getfssec ; Load the data into xfer_buf_seg
pop edi ; <C> Target buffer
pushf ; <C> EOF status
lea ebx,[edi+ecx] ; End of data
.fix_slop:
test cx,dx
jz .noslop
; The last dword fractional - pad with zeroes
; Zero-padding is critical for multi-file initramfs.
mov byte [es:ecx],0
inc cx
jmp short .fix_slop
.noslop:
lea eax,[edi+ecx]
cmp eax,[MyHighMemSize]
ja .overflow
push esi ; <D> File handle/cluster pointer
mov esi,(xfer_buf_seg << 4) ; Source address
call bcopy ; Copy to high memory
pop esi ; <D> File handle/cluster pointer
popf ; <C> EOF status
pop ecx ; <B> Byte count this round
pop eax ; <A> Total bytes to transfer
jc .eof
sub eax,ecx
jnz .read_loop ; More to read... (if ZF=1 then CF=0)
.eof:
pop es ; <AAA> ES
ret
.overflow: mov si,err_nohighmem
jmp abort_load
dot_pause:
push ax
mov al,'.'
call writechr
pop ax
jmp abort_check ; Handles the return
section .data
err_nohighmem db CR, LF
db 'Not enough memory to load specified image.', CR, LF, 0
section .bss
alignb 2
PauseBird resw 1
section .text
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