How to do word ptr [200h] in Fasm?

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peixe

Joined: 18 Oct 2004
Posts: 2

peixe 03 Nov 2004, 12:52

Hi, IÂ´m trying to move a value stored in memory to a register. For example if the memory value is 200h, the value IÂ´m interested in is word size and I want to store it in dx the code I use is the following:

mov dx, word ptr [200h]

Fasm gives this error: "error: invalid expression."

Is "word ptr" valid in Fasm?

[TopicEdit=from:"word ptr" to:"How to do word ptr [200h] in Fasm?" reason:"Better description of the problem"]Matrix[/TopicEdit]

03 Nov 2004, 12:52

vbVeryBeginner

Joined: 15 Aug 2004
Posts: 884
Location: \\world\asia\malaysia

vbVeryBeginner 03 Nov 2004, 13:14

Code:

mov dx,[200]          ;same value moved
mov dx,word [200]   ;same value moved
mov bx,200
mov dx,[bx]            ;same value moved
mov dl,[bx]             ;move a byte to dl

don't need the ptr in fasm and the word is no need because dx is word already

Code:

-r
AX=0000  BX=0000  CX=000F  DX=0000  SP=FFEE  BP=0000  SI=0000  DI=0000
DS=1565  ES=1565  SS=1565  CS=1565  IP=0100   NV UP EI PL NZ NA PO NC
1565:0100 8B16C800      MOV     DX,[00C8]                          DS:00C8=0000
-t

AX=0000  BX=0000  CX=000F  DX=0000  SP=FFEE  BP=0000  SI=0000  DI=0000
DS=1565  ES=1565  SS=1565  CS=1565  IP=0104   NV UP EI PL NZ NA PO NC
1565:0104 8B16C800      MOV     DX,[00C8]                          DS:00C8=0000
-t

AX=0000  BX=0000  CX=000F  DX=0000  SP=FFEE  BP=0000  SI=0000  DI=0000
DS=1565  ES=1565  SS=1565  CS=1565  IP=0108   NV UP EI PL NZ NA PO NC
1565:0108 BBC800        MOV     BX,00C8
-t

AX=0000  BX=00C8  CX=000F  DX=0000  SP=FFEE  BP=0000  SI=0000  DI=0000
DS=1565  ES=1565  SS=1565  CS=1565  IP=010B   NV UP EI PL NZ NA PO NC
1565:010B 8B17          MOV     DX,[BX]                            DS:00C8=0000
-t

AX=0000  BX=00C8  CX=000F  DX=0000  SP=FFEE  BP=0000  SI=0000  DI=0000
DS=1565  ES=1565  SS=1565  CS=1565  IP=010D   NV UP EI PL NZ NA PO NC
1565:010D 8A17          MOV     DL,[BX]                            DS:00C8=00
-t
AX=0000  BX=00C8  CX=000F  DX=0000  SP=FFEE  BP=0000  SI=0000  DI=0000
DS=1565  ES=1565  SS=1565  CS=1565  IP=010F   NV UP EI PL NZ NA PO NC
1565:010F 0000          ADD     [BX+SI],AL                         DS:00C8=00

this thread http://board.flatassembler.net/topic.php?t=2158 contained examples coded in MASM translated to FASM
sincerely,
sulaiman chang

03 Nov 2004, 13:14

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8351
Location: Kraków, Poland

Tomasz Grysztar 03 Nov 2004, 16:40

You can use either:

Code:

mov dx, word ptr 200h

ror

Code:

mov dx, word [200h]

as the "ptr" in fasm does the same what enclosing the value in square brackets, you shouldn't use both at the same time.

03 Nov 2004, 16:40

Matrix

Joined: 04 Sep 2004
Posts: 1166
Location: Overflow

Matrix 03 Nov 2004, 20:14

if you're a short hand converter from masm, you can do these: Smile

Code:

ptr equ
short equ byte
near equ word
far equ dword

mainloop:
mov bx,word ptr [vartest]
jmp short mainloop
vartest:

03 Nov 2004, 20:14

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