In retrospect there is one important area for the Assembly Language Programmer. It would only be interesting to the serious enthusiast. It is writing primitives for very tight Smalltalk. It is the area of embedded systems. Owing to a buggys Windows98se I cannot send attachments (indirectly a good thing). An Example is below.
Regards and rosuccess
---- Redefined Horizons redefined.horizons@gmail.com wrote:
Wow! Great news! Now let me ask about volunteering to help with the project. I'd like to get some experience programming in assembly language and/or machine code. Is there any need for this on the ReactOS project? Can I start on some simple assembly language programming tasks for ReactOS and have someone that can guide me through the tough spots? Let me know if I can help in this area. Scott
On 10/17/05, KJKHyperion hackbunny@reactos.com wrote:
Redefined Horizons wrote:
[1] Is ReactOS built on a Unix core, or is it a new operating sytem from the ground up?
ReactOS is all-original, written from the ground up as a clone of the Windows design
[2] Can you dual boot with ReactOS and a Linux operating system like Debian? If you can, is there a place where I can find instructions on how to do so?
yes, see http://www.reactos.org/wiki/index.php/HOWTO/boot_FreeLoader_from_GRUB
[3] Does an application that runs on Microsoft Windows have to be ported before it can be run on ReactOS?
No
Can I try installing the program to see how it works?
Yes _______________________________________________ ros-general mailing list ros-general@reactos.org http://www.reactos.org/mailman/listinfo/ros-general
------------------------------------------------------------------------------- PAGE 85,132 TITLE User Defined Primitive #92 (INT 62H)
; This is an example of a possible user defined primitive. ; The primitive below "primitive92" is an implementation ; of the String at: primitive. ; ; The first part of the code "installs" the primitive ; "segment and offset" address into INT 62H vector. ; The second part, "primitive92" defines the code that ; will be executed when primitive number 92 from ; "Smalltalk/V" is invoked.
PAGE INCLUDE fixdptrs.usr IF1 INCLUDE access.usr ENDIF
PAGE code SEGMENT ASSUME CS:code,DS:code,ES:code ORG 100H
start: JMP installPrim
PAGE primitive92 PROC FAR
; This is code that will be executed everytime primitive ; number 92 is invoked from "Smalltalk/V"
enterPrimitive ;enter primitive macro (see macro ;listings)
MOV CX,DI ;copy receiver in CX
; getClass DI,DX,ES ;put class of receiver in DX ; ; CMP DX,ClassStringPtr ;if class of receiver is not ; JNE failure ;String then primitive fails ; ;(This check is commnet since it is ; ;not necessary but it is shown here ; ;as an example on how to use the ; ;getClass macro
MOV DI,[BP+16] ;put index argument in DI
SHR DI,1 ;shift right and MOV AX,DI ;copy in AX JNC smallInt ;if no carry (even number) then RCL DI,1 ;its a small integer and jump else ;restore the index object ptr
MOV DX,SS ;set ES to address classes segment SHR DX,1 MOV ES,DX
CMP WORD PTR ES:[DI],ClassLargePosInt ;if class of index object JNE failure ;pointer is LargePositiveInteger ;then continue else primitive fails
getObjectAddress DI,BX,ES ;get address of index object ptr
CMP WORD PTR ES:[BX],4 ;size of this large positive JNE failure ;integer must be 4 (2 bytes for ;size header + 2 bytes for the ;number itself) - not 4 suggests ;that number is more than 2 bytes ;long and primitive fails else
MOV AX,ES:[BX+2] ;move 2 byte integer into AX and JMP haveIndex ;jump to haveIndex
smallInt: JLE failure ;if after shift sign of integer ;changes or its zero then ;primitive fails (index must be ;greater than zero)
haveIndex: INC AX ;index +1 to correct byte access JZ failure ;later on; if value goes to 0 then ;index was too large and primitive ;fails MOV BX,CX ;set BX to receiver object ptr and getObjectAddress BX,DI,ES ;get address of receiver (string)
isSizeEven BX,CX,DS ;check even/odd length of string ;object (JZ for even length)
MOV BX,ES:[DI] ;move size of string to BX
JZ even ;if isSizeEven result is zero DEC BX ;condition flag then length ;of string is even (BX - 2 bytes ;for size header) else length of ;string is odd (BX - 3) so adjust ;size of string (BX) by -1
even: CMP AX,BX ;adjusted index must be less than JAE failure ;BX (string size) else primitive ;fails
;now we must get the character ;from the string and turn it into ;an object pointer XOR CH,CH ;set CH to zero MOV BX,AX ;set BX to be adjusted index MOV CL,ES:[DI+BX] ;move to CL the char from string SHL CX,1 ;multiply CX by 2 ADD CX,FirstCharacterPtr ;add to CX the base character ptr
MOV BX,CX ;set BX to result char pointer exitWithSuccess 1 ;and enter into successful exit ;macro with arg count 1 (the index)
failure: exitWithFailure 1 ;failure macro with arg count 1
primitive92 ENDP
primitive92end LABEL BYTE ;label for exit and stay resident
; This is primitive "installation code" with the exit and ; stay resident
installPrim PROC NEAR MOV AX,CS ;set DS to address code segment MOV DS,AX MOV DX,OFFSET primitive92 ;load DX with primitive offset MOV AX,2562H ;use DOS to set address of INT 62H INT 21H LEA DX,primitive92end ;load DX with address beyond last INT 27H ;byte - exit and stay resident installPrim ENDP SUBTTL PAGE code ENDS END start