metalsvm/arch/x86/kernel/string.asm
2011-08-02 15:58:20 +02:00

94 lines
2.1 KiB
NASM

;
; Written by the Chair for Operating Systems, RWTH Aachen University
;
; NO Copyright (C) 2010-2011, Stefan Lankes
; consider these trivial functions to be public domain.
;
; These functions are distributed on an "AS IS" BASIS,
; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
;
[BITS 32]
SECTION .text
global strcpy
strcpy:
push ebp
mov ebp, esp
push edi
push esi
mov esi, [ebp+12]
mov edi, [ebp+8]
L1:
lodsb
stosb
test al, al
jne L1
mov eax, [ebp+8]
pop esi
pop edi
pop ebp
ret
global strncpy
strncpy:
push ebp
mov ebp, esp
push edi
push esi
mov ecx, [ebp+16]
mov esi, [ebp+12]
mov edi, [ebp+8]
L2:
dec ecx
js L3
lodsb
stosb
test al, al
jne L1
rep
stosb
L3:
mov eax, [ebp+8]
pop esi
pop edi
pop ebp
ret
; The following function is derived from JamesM's kernel development tutorials
; (http://www.jamesmolloy.co.uk/tutorial_html/)
global copy_page_physical
copy_page_physical:
push esi ; According to __cdecl, we must preserve the contents of ESI
push edi ; and EDI.
pushf ; push EFLAGS, so we can pop it and reenable interrupts
; later, if they were enabled anyway.
cli ; Disable interrupts, so we aren't interrupted.
; Load these in BEFORE we disable paging!
mov edi, [esp+12+4] ; Destination address
mov esi, [esp+12+8] ; Source address
mov edx, cr0 ; Get the control register...
and edx, 0x7fffffff ; and...
mov cr0, edx ; Disable paging.
cld
mov ecx, 0x400 ; 1024*4bytes = 4096 bytes = page size
rep movsd ; copy page
mov edx, cr0 ; Get the control register again
or edx, 0x80000000 ; and...
mov cr0, edx ; Enable paging.
popf ; Pop EFLAGS back.
pop edi ; Get the original value of EDI
pop esi ; and ESI back.
ret
SECTION .note.GNU-stack noalloc noexec nowrite progbits