ack/plat/msdos386/libsys/sys_rawwrite.s

71 lines
1.2 KiB
ArmAsm

#
! $Source$
! $State$
! $Revision$
! Declare segments (the order is important).
.sect .text
.sect .rom
.sect .data
.sect .bss
.sect .text
.extern pmode_ds
.extern pmode_cs
.extern rmode
.extern transfer_buffer_ptr
.extern interrupt_ptr
! Write bytes to/to a file descriptor. These routines do not do any
! translation between CRLF and LF line endings.
!
! Note that, for MS-DOS, a raw "write" request of zero bytes will truncate
! (or extend) the file to the current file position.
.define __sys_rawwrite
__sys_rawwrite:
enter 4, 0
amount_transferred = -1*4
file_handle = 2*4
read_buffer = 3*4
amount_to_write = 4*4
mov es, (pmode_ds)
mov amount_transferred(ebp), 0
mainloop:
mov ecx, 32*1024
cmp amount_to_write(ebp), ecx
jge 2f
mov ecx, amount_to_write(ebp)
test ecx, ecx
jz exit
2:
! Copy ecx bytes into the transfer buffer.
push ecx
mov esi, read_buffer(ebp)
movzx edi, (transfer_buffer_ptr)
rep movsb
pop ecx
movb ah, 0x40
o16 mov dx, (transfer_buffer_ptr)
o16 mov bx, file_handle(ebp)
or ebx, 0x210000
callf (interrupt_ptr)
movzx eax, ax
add read_buffer(ebp), eax
add amount_transferred(ebp), eax
sub amount_to_write(ebp), eax
jmp mainloop
exit:
mov eax, amount_to_write(ebp)
leave
ret