ack/plat/msdos386/libsys/sys_isopen.s
tkchia cba54b205b plat/msdos386: refactor, firm up, and optimize
- refactor code for transfer buffer reads/writes, real mode
   int 0x21 calls, and assembler segment declarations
 - define transfer buffer size in one place
 - beef up error checking for transfer buffer operations
   (prevent buffer overflows)
 - also optimize such operations to transfer dword by dword
   where feasible
2022-08-26 17:31:28 +00:00

19 lines
256 B
ArmAsm

#
! $Source$
! $State$
! $Revision$
#include "libsysasm.h"
! Say whether a given file descriptor number refers to a valid open file
! descriptor.
.define __sys_isopen
__sys_isopen:
mov ebx, 4(esp)
mov eax, 0x4400
int 0x21
sbb eax, eax
inc eax
ret