diff --git a/plat/msdos86/libsys/getpid.s b/plat/msdos86/libsys/getpid.s index 009c4f9f4..5aa80638b 100644 --- a/plat/msdos86/libsys/getpid.s +++ b/plat/msdos86/libsys/getpid.s @@ -3,6 +3,18 @@ ! $State$ ! $Revision$ +! Copyright (c) 2021--2022 TK Chia +! +! The authors hereby grant permission to use, copy, modify, distribute, +! and license this software and its documentation for any purpose, provided +! that existing copyright notices are retained in all copies and that this +! notice is included verbatim in any distributions. No written agreement, +! license, or royalty fee is required for any of the authorized uses. +! Modifications to this software may be copyrighted by their authors +! and need not follow the licensing terms described here, provided that +! the new terms are clearly indicated on the first page of each file where +! they apply. + ! Declare segments (the order is important). .sect .text @@ -13,15 +25,21 @@ .sect .text ! Get the current process identifier. For MS-DOS, use the Program Segment -! Prefix (PSP) segment as the PID. +! Prefix (PSP) segment as the PID, unless the system supports an actual +! `getpid' syscall, e.g. European MS-DOS 4.0. ! -! (Note that pid_t is a 32-bit type. This is to allow for PSP addresses -! above 0x7FFF:0.) +! (Note that pid_t is a 32-bit type. This is to allow for PSP segments and +! MS-DOS PIDs above 0x7FFF.) .define _getpid _getpid: + movb ah, 0x87 + stc + int 0x21 + jnc .eur_dos movb ah, 0x51 int 0x21 xchg bx, ax +.eur_dos: xor dx, dx ret