;; Common code for running a COMBOOT image
;;
+; Parameter registers definition; this is the definition
+; of the stack frame used by INT 21h and INT 22h.
+%define P_FLAGS word [bp+40]
+%define P_FLAGSL byte [bp+40]
+%define P_FLAGSH byte [bp+41]
+%define P_DS word [bp+34]
+%define P_ES word [bp+32]
+%define P_EAX dword [bp+28]
+%define P_AX word [bp+28]
+%define P_HAX word [bp+30]
+%define P_AL byte [bp+28]
+%define P_AH byte [bp+29]
+%define P_ECX dword [bp+24]
+%define P_CX word [bp+24]
+%define P_HCX word [bp+26]
+%define P_CL byte [bp+24]
+%define P_CH byte [bp+25]
+%define P_EDX dword [bp+20]
+%define P_DX word [bp+20]
+%define P_HDX word [bp+22]
+%define P_DL byte [bp+20]
+%define P_DH byte [bp+21]
+%define P_EBX dword [bp+16]
+%define P_BX word [bp+16]
+%define P_HBX word [bp+18]
+%define P_BL byte [bp+16]
+%define P_BH byte [bp+17]
+%define P_EBP dword [bp+8]
+%define P_BP word [bp+8]
+%define P_HBP word [bp+10]
+%define P_ESI dword [bp+4]
+%define P_SI word [bp+4]
+%define P_HSI word [bp+6]
+%define P_EDI dword [bp]
+%define P_DI word [bp]
+%define P_HDI word [bp+2]
+
; Looks like a COMBOOT image but too large
comboot_too_large:
mov si,err_comlarge
ret
; INT 21h: generic DOS system call
-comboot_int21: push ds
- push cs
- pop ds ; Set DS <- CS
- and ah,ah ; 00 = return
- je comboot_return
- cmp ah,02h
- jb comboot_getkeyecho ; 01 = get key with echo
- je comboot_writechr ; 02 = writechr
- cmp ah,08h ; 08 = get key w/o echo
- je comboot_getkey
- cmp ah,09h ; 09 = writestr
- je comboot_writestr
- cmp ah,0Bh ; 0B = check keyboard
- je comboot_checkkey
- cmp ah,30h ; 30 = check version
- je comboot_checkver
- cmp ah,4Ch ; 4C = return with status
- je comboot_return
-
- ; Otherwise fall through to comboot_bogus
+comboot_int21: cli
+ push ds
+ push es
+ pushad
+ mov bp,cs
+ mov ds,bp
+ mov es,bp
+ mov bp,sp ; Set up stack frame
+
+ mov cx,int21_count
+ mov si,int21_table
+.again: lodsb
+ cmp al,P_AH
+ lodsw
+ loopne .again
+ ; The last function in the list is the
+ ; "no such function" function
+
+ call ax ; Call the invoked function
+comboot_resume:
+ setc P_FLAGSL ; Propagate CF->error
+ popad
+ pop es
+ pop ds
+ iret
; Attempted to execute non-21h DOS system call
comboot_bogus: cli ; Don't trust anyone
;
; INT 21h system calls
;
-comboot_getkeyecho: ; 01 = get key with echo
+comboot_getkey: ; 01 = get key with echo
call vgashowcursor
- call getchar
+ call comboot_getchar
call vgahidecursor
call writechr
- jmp comboot_resume_ok
+ clc
+ ret
comboot_writechr: ; 02 = writechr
- xchg ax,dx
+ mov al,P_DL
call writechr
- xchg ax,dx
- jmp comboot_resume_ok
+ clc
+ ret
-comboot_getkey: ; 08 = get key w/o echo
- call vgashowcursor
- call getchar
- call vgahidecursor
- jmp comboot_resume_ok
+comboot_writeserial: ; 04 = write serial port
+ mov al,P_DL
+ call write_serial
+ clc
+ ret
+
+comboot_getkeynoecho: ; 08 = get key w/o echo
+ call comboot_getchar
+ clc
+ ret
comboot_writestr: ; 09 = write string
- pusha
- push es
- mov bp,sp
- mov es,[bp-20] ; Old DS
- mov si,dx
+ mov es,P_DS
+ mov si,P_DX
.loop: es lodsb
cmp al,'$' ; End string with $ - bizarre
je .done
call writechr
jmp short .loop
-.done: pop es
- popa
- jmp comboot_resume_ok
+.done: clc
+ ret
comboot_checkkey: ; 0B = check keyboard status
+ cmp byte [APIKeyFlag],00h
+ jnz .waiting
call pollchar
- setz al
+.waiting: setz al
dec al ; AL = 0FFh if present, 0 if not
- jmp comboot_resume_ok
+ mov P_AL,al
+ clc
+ ret
comboot_checkver: ; 30 = check DOS version
; We return 0 in all DOS-compatible version registers,
; but the high part of eax-ebx-ecx-edx spell "SYSLINUX"
- mov eax,'SY' << 16
- mov ebx,'SL' << 16
- mov ecx,'IN' << 16
- mov edx,'UX' << 16
- ;jmp comboot_resume_ok
-
-;
-; Resume comboot execution
-;
-comboot_resume_ok:
+ mov P_EAX,'SY' << 16
+ mov P_EBX,'SL' << 16
+ mov P_ECX,'IN' << 16
+ mov P_EDX,'UX' << 16
clc
-comboot_resume:
- pop ds
- iret
+ ret
-comboot_apierr:
- stc
- jmp comboot_resume
+comboot_getchar:
+ cmp byte [APIKeyFlag],00h
+ jne .queued
+ call getchar ; If not queued get input
+ and al,al ; Function key?
+ jnz .done
+ mov [APIKeyWait],ah ; High part of key
+ inc byte [APIKeyFlag] ; Set flag
+.done: mov P_AL,al
+ ret
+.queued: mov al,[APIKeyWait]
+ dec byte [APIKeyFlag]
+ jmp .done
;
; INT 22h - SYSLINUX-specific system calls
; System call number in ax
;
comboot_int22:
+ cli
push ds
- push cs
- pop ds
+ push es
+ pushad
+ mov bp,cs
+ mov ds,bp
+ mov es,bp
+ mov bp,sp ; Set up stack frame
cmp ax,int22_count
jb .ok
;
comapi_get_version:
; Number of API functions supported
- mov ax,int22_count
+ mov P_AX,int22_count
; SYSLINUX version
- mov cx,(VER_MAJOR << 8)+VER_MINOR
+ mov P_CX,(VER_MAJOR << 8)+VER_MINOR
; SYSLINUX derivative ID byte
- mov dx,my_id
+ mov P_DX,my_id
; For future use
- xor bx,bx
+ mov P_BX,cs ; cs == 0
- push cs
- pop es
+ mov P_ES,ds
; ES:SI -> version banner
- mov si,syslinux_banner
+ mov P_SI,syslinux_banner
; ES:DI -> copyright string
- mov di,copyright_str
+ mov P_DI,copyright_str
comapi_nop:
clc
; Write null-terminated string in ES:BX
;
comapi_writestr:
- push es
- pop ds
- mov si,ax
- jmp writestr ; Write string from ES:BX
+ mov ds,P_ES
+ mov si,P_BX
+ call writestr
+ clc
+ ret
;
; INT 22h AX=0003h Run command
; ES:BX as if it had been entered by the user.
;
comapi_run:
- push es
- push ds
- pop es
- pop ds
- mov si,ax
+ mov ds,P_ES
+ mov si,P_BX
mov di,command_line
.copyloop:
lodsb
;
comapi_open:
push ds
- push ds
- push es
- pop ds
- pop es
+ mov ds,P_ES
+ mov si,P_SI
mov di,InitRD
push di
call mangle_name
pop ds
call searchdir
jz .err
- xchg eax,edx
- shr eax,16
- xchg ax,dx
- mov cx,[ClustSize]
+ mov P_AX,ax
+ mov P_HAX,dx
+ mov ax,[ClustSize]
+ mov P_CX,ax
clc
ret
.err:
; INT 22h AX=0007h Read file
;
comapi_read:
- xchg ax,bx
+ mov ax,P_BX
+ mov si,P_SI
call getfssec
jnc .noteof
xor si,si ; SI <- 0 on EOF, CF <- 0
-.noteof: ret
+.noteof: mov P_SI,si
+ ret
;
; INT 22h AX=0008h Close file
;
%if IS_PXELINUX
comapi_pxecall:
+ mov bx,P_BX
+ mov es,P_ES
+ mov di,P_DI
call far [PXENVEntry]
clc
ret
comapi_pxecall equ comapi_err ; Not available
%endif
+;
+; This stuff should really be in the data section...
+;
+%macro int21 2
+ db %1
+ dw %2
+%endmacro
+
+int21_table:
+ int21 00h, comboot_return
+ int21 01h, comboot_getkey
+ int21 02h, comboot_writechr
+ int21 04h, comboot_writeserial
+ int21 08h, comboot_getkey
+ int21 09h, comboot_writestr
+ int21 0Bh, comboot_checkkey
+ int21 30h, comboot_checkver
+ int21 4Ch, comboot_return
+ int21 00h, comboot_bogus
+int21_count equ ($-int21_table)/3
+
align 2, db 0
int22_table:
dw comapi_err ; 0000 unimplemented syscall
dw comapi_close ; 0008 close file
dw comapi_pxecall ; 0009 call PXE stack
int22_count equ ($-int22_table)/2
+
+APIKeyWait db 0
+APIKeyFlag db 0
projects / profile / ivi / syslinux.git / commitdiff