As a result of noob!'s post about using a text string as an immediate operand for dwords
and it being stored in an unobvious order, the reverse of text strings in the .data section,
I wrote a macro txt4 which works for 4 byte strings, but a more flexible version that
works for 2,4,8,16 byte immediate operand strings would be better.
txt4 MACRO text:VARARG
nustr equ <>
slen SIZESTR <text>
;; ------------------------------------------------
;; test for errors in length
;; ------------------------------------------------
if slen ne 6
echo ------------------------------------
echo *** STRING TOO SHORT or TOO LONG ***
echo ------------------------------------
.ERR
EXITM <>
endif
;; ------------------------------------------------
;; create a new string in reverse order
;; ------------------------------------------------
nustr1 SUBSTR <text>,1,1
nustr2 SUBSTR <text>,2,1
nustr3 SUBSTR <text>,3,1
nustr4 SUBSTR <text>,4,1
nustr5 SUBSTR <text>,5,1
nustr6 SUBSTR <text>,6,1
nustr CATSTR nustr6,nustr5,nustr4,nustr3,nustr2,nustr1
EXITM nustr
ENDM
A unfinished version of txt, it checks for the string lengths correctly but doesn't do the reverse function.
txt MACRO text:VARARG
nustr equ <>
slen SIZESTR <text>
;; ------------------------------------------------
;; test for errors in length
;; ------------------------------------------------
if NOT ((slen eq 4) OR (slen eq 6) OR (slen eq 10) OR (slen eq 18))
echo ------------------------------------
echo *** STRING TOO SHORT or TOO LONG ***
echo ------------------------------------
.ERR
EXITM <>
endif
;; ------------------------------------------------
;; create a new string in reverse order
;; ------------------------------------------------
mustr SUBSTR <text>,1,slen
% FORC arg, <mustr>
ENDM
EXITM nustr
ENDM
Anyone know how to reverse the string in a flexible way using FORC
or some other way?
Quote from: dsouza123 on August 09, 2008, 06:47:48 PM
Anyone know how to reverse the string in a flexible way using FORC
or some other way?
include \masm32\include\masm32rt.inc
txt MACRO arg:REQ
LOCAL tmp$, parseLen, PP
PP=0
tmp$ equ <>
parseLen = @SizeStr(arg)
WHILE PP lt parseLen
PP=PP+1
tmp$ CATSTR @SubStr(arg, PP, 1), tmp$
ENDM
% echo tmp$
EXITM <tmp$>
ENDM
.code
MyText db "Hello World", 0
AppName db "Masm32:", 0
start:
mov eax, txt("Masm")
mov edx, offset AppName
mov edx, [edx]
.if eax==edx
invoke MessageBox, 0, chr$("Bingo!"), addr AppName, MB_OK
.else
invoke MessageBox, 0, chr$("No success, sooory!"), addr AppName, MB_OK
.endif
exit
end start
Thanks jj2007, that works well.
% echo tmp$, that is is a cool trick to see resulting value of the string during assembly.
I was still curious if it could be done using FORC,
using MAZEGEN's $lcase and $ucase macros
for examples on using FORC, this the result.
txt MACRO text:REQ
local nustr, letter, char
slen SIZESTR <text>
;; ------------------------------------------------
;; test for errors in length
;; ------------------------------------------------
if NOT ((slen eq 4) OR (slen eq 6) OR (slen eq 10) OR (slen eq 18))
echo ------------------------------------
echo *** STRING TOO SHORT or TOO LONG ***
echo ------------------------------------
.ERR
EXITM <>
endif
;; ------------------------------------------------
;; create a new string in reverse order
;; ------------------------------------------------
nustr equ <>
FORC letter, <text>
char TEXTEQU <letter>
nustr CATSTR char, nustr
ENDM
EXITM nustr
ENDM
Quote from: dsouza123 on August 09, 2008, 09:34:50 PM
Thanks jj2007, that works well.
% echo tmp$, that is is a cool trick to see resulting value of the string during assembly.
When developing complex macros, I sometimes add this line:
% echo tmp$
crash
.. to test a specific bit of code.
Quote
I was still curious if it could be done using FORC
Try your luck... for me this excerpt from the Programmer's Guide is pure Chinese. Anyway, SUBSTR works fine. You can slightly shorten it by dropping parselen:
WHILE PP lt @SizeStr(arg)FORC Loops
The FORC directive is similar to FOR, but takes a string of text rather than a list of arguments. The statements are assembled once for each character (including spaces) in the string, substituting a different character for the parameter each time through.
The syntax looks like this:
FORC parameter, < text>
statements
ENDM
The text must be enclosed in angle brackets. The following example illustrates FORC:
FORC arg, <ABCDEFGHIJKLMNOPQRSTUVWXYZ>
BYTE '&arg' ;; Allocate uppercase letter
BYTE '&arg' + 20h ;; Allocate lowercase letter
BYTE '&arg' - 40h ;; Allocate ordinal of letter
ENDM
Notice that the substitution operator must be used inside the quotation marks to make sure that arg is expanded to a character rather than treated as a literal string.
With versions of MASM earlier than 6.0, FORC is often used for complex parsing tasks. A long sentence can be examined character by character. Each character is then either thrown away or pasted onto a token string, depending on whether it is a separator character. The new predefined macro functions and string processing directives discussed in the following section are usually more efficient for these tasks.
Quote from: jj2007 on August 09, 2008, 11:03:17 PM
Quote from: dsouza123 on August 09, 2008, 09:34:50 PM
I was still curious if it could be done using FORC
Try your luck... for me this excerpt from the Programmer's Guide is pure Chinese
I learnt Chinese :toothy
txt MACRO arg:REQ
LOCAL tmp$
tmp$ equ <>
FORC char, <arg>
tmp$ CATSTR <char>, tmp$
ENDM
EXITM <tmp$>
ENDM