2 ;; -----------------------------------------------------------------------
4 ;; Copyright 1994-2002 H. Peter Anvin - All Rights Reserved
6 ;; This program is free software; you can redistribute it and/or modify
7 ;; it under the terms of the GNU General Public License as published by
8 ;; the Free Software Foundation, Inc., 53 Temple Place Ste 330,
9 ;; Bostom MA 02111-1307, USA; either version 2 of the License, or
10 ;; (at your option) any later version; incorporated herein by reference.
12 ;; -----------------------------------------------------------------------
17 ;; Common code for running a COMBOOT image
20 ; Parameter registers definition; this is the definition
21 ; of the stack frame used by INT 21h and INT 22h.
22 %define P_FLAGS word [bp+40]
23 %define P_FLAGSL byte [bp+40]
24 %define P_FLAGSH byte [bp+41]
25 %define P_CS word [bp+38]
26 %define P_IP word [bp+36]
27 %define P_DS word [bp+34]
28 %define P_ES word [bp+32]
29 %define P_EAX dword [bp+28]
30 %define P_AX word [bp+28]
31 %define P_HAX word [bp+30]
32 %define P_AL byte [bp+28]
33 %define P_AH byte [bp+29]
34 %define P_ECX dword [bp+24]
35 %define P_CX word [bp+24]
36 %define P_HCX word [bp+26]
37 %define P_CL byte [bp+24]
38 %define P_CH byte [bp+25]
39 %define P_EDX dword [bp+20]
40 %define P_DX word [bp+20]
41 %define P_HDX word [bp+22]
42 %define P_DL byte [bp+20]
43 %define P_DH byte [bp+21]
44 %define P_EBX dword [bp+16]
45 %define P_BX word [bp+16]
46 %define P_HBX word [bp+18]
47 %define P_BL byte [bp+16]
48 %define P_BH byte [bp+17]
49 %define P_EBP dword [bp+8]
50 %define P_BP word [bp+8]
51 %define P_HBP word [bp+10]
52 %define P_ESI dword [bp+4]
53 %define P_SI word [bp+4]
54 %define P_HSI word [bp+6]
55 %define P_EDI dword [bp]
56 %define P_DI word [bp]
57 %define P_HDI word [bp+2]
59 ; Looks like a COMBOOT image but too large
66 ; Load a COMBOOT image. A COMBOOT image is basically a DOS .COM file,
67 ; except that it may, of course, not contain any DOS system calls. We
68 ; do, however, allow the execution of INT 20h to return to SYSLINUX.
73 cmp ax,0ff00h ; Max size in bytes
76 call comboot_setup_api
81 mov bx,100h ; Load at <seg>:0100h
83 mov cx,[ClustPerMoby] ; Absolute maximum # of clusters
87 mov cx,64 ; 256 bytes (size of PSP)
88 xor eax,eax ; Clear PSP
91 mov word [es:0], 020CDh ; INT 20h instruction
92 ; First non-free paragraph
93 mov word [es:02h], comboot_seg+1000h
95 ; Copy the command line from high memory
96 mov cx,125 ; Max cmdline len (minus space and CR)
98 mov di,081h ; Offset in PSP for command line
99 mov al,' ' ; DOS command lines begin with a space
102 comboot_cmd_cp: lodsb
107 comboot_end_cmd: mov al,0Dh ; CR after last character
109 mov al,126 ; Include space but not CR
111 mov [es:80h], al ; Store command line length
114 mov [SavedSSSP+2],ss ; Save away SS:SP
120 push word 0 ; Return to address 0 -> exit
122 jmp comboot_seg:100h ; Run it
124 ; Proper return vector
125 comboot_return: cli ; Don't trust anyone
130 ; Set up the COMBOOT API interrupt vectors. This is also used
134 mov di,4*0x20 ; DOS interrupt vectors
135 mov eax,comboot_return ; INT 20h = exit
137 mov ax,comboot_int21 ; INT 21h = DOS-compatible syscalls
139 mov ax,comboot_int22 ; INT 22h = proprietary syscalls
142 mov cx,29 ; All remaining DOS vectors
146 ; INT 21h: generic DOS system call
155 mov bp,sp ; Set up stack frame
163 ; The last function in the list is the
164 ; "no such function" function
166 call ax ; Call the invoked function
168 setc P_FLAGSL ; Propagate CF->error
174 ; Attempted to execute non-21h DOS system call
175 comboot_bogus: cli ; Don't trust anyone
178 ; Generic COMBOOT return to command line code
179 ; AX -> message (if any)
180 ; BX -> where to go next
183 mov bx,enter_command ; Normal return to command prompt
184 comboot_exit_special:
200 ; INT 21h system calls
202 comboot_getkey: ; 01 = get key with echo
210 comboot_writechr: ; 02 = writechr
216 comboot_writeserial: ; 04 = write serial port
222 comboot_getkeynoecho: ; 08 = get key w/o echo
227 comboot_writestr: ; 09 = write string
231 cmp al,'$' ; End string with $ - bizarre
238 comboot_checkkey: ; 0B = check keyboard status
239 cmp byte [APIKeyFlag],00h
243 dec al ; AL = 0FFh if present, 0 if not
248 comboot_checkver: ; 30 = check DOS version
249 ; We return 0 in all DOS-compatible version registers,
250 ; but the high part of eax-ebx-ecx-edx spell "SYSLINUX"
259 cmp byte [APIKeyFlag],00h
261 call getchar ; If not queued get input
262 and al,al ; Function key?
264 mov [APIKeyWait],ah ; High part of key
265 inc byte [APIKeyFlag] ; Set flag
268 .queued: mov al,[APIKeyWait]
269 dec byte [APIKeyFlag]
273 ; INT 22h - SYSLINUX-specific system calls
274 ; System call number in ax
285 mov bp,sp ; Set up stack frame
289 xor ax,ax ; Function 0 -> unimplemented
293 call [bx+int22_table]
294 jmp comboot_resume ; On return
297 ; INT 22h AX=0000h Unimplemented call
304 ; INT 22h AX=0001h Get SYSLINUX version
307 ; Number of API functions supported
310 mov P_CX,(VER_MAJOR << 8)+VER_MINOR
311 ; SYSLINUX derivative ID byte
314 mov P_BX,cs ; cs == 0
317 ; ES:SI -> version banner
318 mov P_SI,syslinux_banner
319 ; ES:DI -> copyright string
320 mov P_DI,copyright_str
327 ; INT 22h AX=0002h Write string
329 ; Write null-terminated string in ES:BX
339 ; INT 22h AX=0003h Run command
341 ; Terminates the COMBOOT program and executes the command line in
342 ; ES:BX as if it had been entered by the user.
354 mov bx,load_kernel ; Run a new kernel
355 jmp comboot_exit_special ; Terminate task, clean up
358 ; INT 22h AX=0004h Run default command
360 ; Terminates the COMBOOT program and executes the default command line
361 ; as if a timeout had happened or the user pressed <Enter>.
365 jmp comboot_exit_special
368 ; INT 22h AX=0005h Force text mode
370 ; Puts the video in standard text mode
378 ; INT 22h AX=0006h Open file
403 ; INT 22h AX=0007h Read file
410 xor si,si ; SI <- 0 on EOF, CF <- 0
415 ; INT 22h AX=0008h Close file
418 ; Do nothing for now. Eventually implement
419 ; an internal API for this.
424 ; INT 22h AX=0009h Call PXE stack
431 call far [PXENVEntry]
435 comapi_pxecall equ comapi_err ; Not available
439 ; INT 22h AX=000Ah Get Derivative-Specific Info
444 mov al,[bsDriveNumber]
465 ; INT 22h AX=000Bh Get Serial Console Configuration
481 ; This stuff should really be in the data section...
489 int21 00h, comboot_return
490 int21 01h, comboot_getkey
491 int21 02h, comboot_writechr
492 int21 04h, comboot_writeserial
493 int21 08h, comboot_getkey
494 int21 09h, comboot_writestr
495 int21 0Bh, comboot_checkkey
496 int21 30h, comboot_checkver
497 int21 4Ch, comboot_return
498 int21 00h, comboot_bogus
499 int21_count equ ($-int21_table)/3
503 dw comapi_err ; 0000 unimplemented syscall
504 dw comapi_get_version ; 0001 get SYSLINUX version
505 dw comapi_writestr ; 0002 write string
506 dw comapi_run ; 0003 run specified command
507 dw comapi_run_default ; 0004 run default command
508 dw comapi_textmode ; 0005 force text mode
509 dw comapi_open ; 0006 open file
510 dw comapi_read ; 0007 read file
511 dw comapi_close ; 0008 close file
512 dw comapi_pxecall ; 0009 call PXE stack
513 dw comapi_derinfo ; 000A derivative-specific info
514 dw comapi_serialcfg ; 000B get serial port config
515 int22_count equ ($-int22_table)/2