138 lines
2.9 KiB
ArmAsm
Executable file
138 lines
2.9 KiB
ArmAsm
Executable file
! Mkfhead.s - DOS & BIOS support for mkfile.c Author: Kees J. Bot
|
|
! 9 May 1998
|
|
!
|
|
! This file contains the startup and low level support for the MKFILE.COM
|
|
! utility. See doshead.ack.s for more comments on .COM files.
|
|
!
|
|
.sect .text; .sect .rom; .sect .data; .sect .bss
|
|
.sect .text
|
|
|
|
.define _PSP
|
|
_PSP:
|
|
.space 256 ! Program Segment Prefix
|
|
|
|
mkfile:
|
|
cld ! C compiler wants UP
|
|
xor ax, ax ! Zero
|
|
mov di, _edata ! Start of bss is at end of data
|
|
mov cx, _end ! End of bss (begin of heap)
|
|
sub cx, di ! Number of bss bytes
|
|
shr cx, 1 ! Number of words
|
|
rep stos ! Clear bss
|
|
|
|
xor cx, cx ! cx = argc
|
|
xor bx, bx
|
|
push bx ! argv[argc] = NULL
|
|
movb bl, (_PSP+0x80) ! Argument byte count
|
|
0: movb _PSP+0x81(bx), ch ! Null terminate
|
|
dec bx
|
|
js 9f
|
|
cmpb _PSP+0x81(bx), 0x20 ! Whitespace?
|
|
jbe 0b
|
|
1: dec bx ! One argument character
|
|
js 2f
|
|
cmpb _PSP+0x81(bx), 0x20 ! More argument characters?
|
|
ja 1b
|
|
2: lea ax, _PSP+0x81+1(bx) ! Address of argument
|
|
push ax ! argv[n]
|
|
inc cx ! argc++;
|
|
test bx, bx
|
|
jns 0b ! More arguments?
|
|
9: movb _PSP+0x81(bx), ch ! Make a null string
|
|
lea ax, _PSP+0x81(bx)
|
|
push ax ! to use as argv[0]
|
|
inc cx ! Final value of argc
|
|
mov ax, sp
|
|
push ax ! argv
|
|
push cx ! argc
|
|
call _main ! main(argc, argv)
|
|
push ax
|
|
call _exit ! exit(main(argc, argv))
|
|
|
|
! int creat(const char *path, mode_t mode)
|
|
! Create a file with the old creat() call.
|
|
.define _creat
|
|
_creat:
|
|
mov bx, sp
|
|
mov dx, 2(bx) ! Filename
|
|
xor cx, cx ! Ignore mode, always read-write
|
|
movb ah, 0x3C ! "CREAT"
|
|
dos: int 0x21 ! ax = creat(path, 0666);
|
|
jc seterrno
|
|
ret
|
|
|
|
seterrno:
|
|
mov (_errno), ax ! Set errno to the DOS error code
|
|
mov ax, -1
|
|
cwd ! return -1L;
|
|
ret
|
|
|
|
! int open(const char *path, int oflag)
|
|
! Open a file with the oldfashioned two-argument open() call.
|
|
.define _open
|
|
_open:
|
|
mov bx, sp
|
|
mov dx, 2(bx) ! Filename
|
|
movb al, 4(bx) ! O_RDONLY, O_WRONLY, O_RDWR
|
|
movb ah, 0x3D ! "OPEN"
|
|
jmp dos
|
|
|
|
! int close(int fd)
|
|
! Close an open file.
|
|
.define _close
|
|
_close:
|
|
mov bx, sp
|
|
mov bx, 2(bx) ! bx = file handle
|
|
movb ah, 0x3E ! "CLOSE"
|
|
jmp dos
|
|
|
|
! void exit(int status)
|
|
! void _exit(int status)
|
|
! Return to DOS.
|
|
.define _exit, __exit, ___exit
|
|
_exit:
|
|
__exit:
|
|
___exit:
|
|
pop ax
|
|
pop ax ! al = status
|
|
movb ah, 0x4C ! "EXIT"
|
|
int 0x21
|
|
hlt
|
|
|
|
! ssize_t read(int fd, void *buf, size_t n)
|
|
! Read bytes from an open file.
|
|
.define _read
|
|
_read:
|
|
mov bx, sp
|
|
mov cx, 6(bx)
|
|
mov dx, 4(bx)
|
|
mov bx, 2(bx)
|
|
movb ah, 0x3F ! "READ"
|
|
jmp dos
|
|
|
|
! ssize_t write(int fd, const void *buf, size_t n)
|
|
! Write bytes to an open file.
|
|
.define _write
|
|
_write:
|
|
mov bx, sp
|
|
mov cx, 6(bx)
|
|
mov dx, 4(bx)
|
|
mov bx, 2(bx)
|
|
movb ah, 0x40 ! "WRITE"
|
|
jmp dos
|
|
|
|
! off_t lseek(int fd, off_t offset, int whence)
|
|
! Set file position for read or write.
|
|
.define _lseek
|
|
_lseek:
|
|
mov bx, sp
|
|
movb al, 8(bx) ! SEEK_SET, SEEK_CUR, SEEK_END
|
|
mov dx, 4(bx)
|
|
mov cx, 6(bx) ! cx:dx = offset
|
|
mov bx, 2(bx)
|
|
movb ah, 0x42 ! "LSEEK"
|
|
jmp dos
|
|
|
|
!
|
|
! $PchId: mkfhead.ack.s,v 1.3 1999/01/14 21:17:06 philip Exp $
|