assembly - Reading Hex as String -

-

im not in coding in assembly, need write in assembly anyways here trying do. (i'm using masm32)

.data         msg    db    31h, 00h, 32h, 00h, 33h  ;convert string "123"      .code      start:          invoke messagebox, 0, addr msg, 0, 0         call exitprocess     end start

as can see each character or byte separated null byte, can show 1 byte, "1" instead of "123"

if can concatenate each readable byte until reaches end of string.

mov ebx, offset msg mov ecx, ebx add ebx, 2 invoke lstrcat, ebx, ecx

maybe add loop also, don't know better way code or if have better solution can share.

in order work on string, need know length of string. done using null terminate string. functions not take string length argument, 00h, , print string it, messagebox doing, printing "1" , seeing next character 00h, stops printing.

in case, there no null terminator @ end of string, can string length @ assembly time symbol "$" current value of location counter.

msg         db    31h, 00h, 32h, 00h, 33h  ;convert string "123" msg_len     equ $ - msg

which means, take address of $ , subtract address of msg, , replace msg_len value.

include masm32rt.inc  .data msg         db    31h, 00h, 32h, 00h, 33h ;convert string "123" msg_len     equ $ - msg  .data? msg_new     db  msg_len + 1 dup (?)  .code start:      xor     ecx, ecx                ; index source array     xor     edx, edx                ; index dest array     lea     esi, msg     lea     edi, msg_new convertit:     mov     al, byte ptr[esi + ecx] ; byte @ pointer + index     cmp     al, 0                   ; 0?     jne     @f                      ; no, add dest array     inc     ecx                     ; yes, increase source index     jmp     checkforend             ; check see if @ end  @@:     mov     byte ptr [edi + edx], al; add byte dest array     inc     ecx                     ; increase both indexes     inc     edx                     ;   checkforend:     cmp     ecx, msg_len            ; check end - if ecx == msg_len done     jne     convertit               ; if ecx != msg_len, continue loop      mov     byte ptr [edi + edx], 0 ; don't forget null terminate dest string      invoke  messagebox, hwnd_desktop, offset msg_new, null, mb_ok     invoke  exitprocess, 0 end start

this can done less code , "converting" string "in place" beyond scope here.

@nik, of love assembly , don't use else.


Comments

Post a Comment

Popular posts from this blog

css - Which browser returns the correct result for getBoundingClientRect of an SVG element? -

-
this svg contains rect overflows svg element: <svg id='svg' width='10' height='10'> <rect x='-10' y='-10' width='30' height='30'/> </svg> chrome 28 , opera 12 return getboundingclientrect() svg element width , height of 10. firefox 23 reports width , height of 30. correct? jsfiddle the relevant spec cssom , delegates svg spec if svg element not "have associated css layout box". haven't found definition of "having associated css layout box", correct result seem hinge on definition, getbbox returns 30x30 rect in browsers. this firefox bug fixed now, fix in firefox nightlies , should make through firefox 33 released on 14 october 2014. see bug 530985 details.
Read more

gcc - Calling fftR4() in c from assembly -

-
i trying asm fft implementation www.embeddedsignals.com work. running make gives error: undefined reference fftr4(short*, short*, int) at top of asm have .syntax unified .thumb .global fftr4 .type fftr4, %function and there #define's associate c functions arguments registers followed macros fftr4 function uses. after that, fftr4 called .thumb_func fftr4: stmfd sp!, {r4-r11, lr} mov tmp0, #0 // bit reversed counter mov tmp1, #0 .word 0xf3a2fa92 //rbit r3,r2 //rbit r,n lsl r,#3 and c code follows: void fftr4(short *y, short *x, int n); short x[512]; short y[512]; int i; void loop() { (i=0;i<512;i++) x[i]=0; (i=0;i<512;i=i+8) { x[i+0]=16384; x[i+2]=16384; x[i+4]=-16384; x[i+6]=-16384;} fftr4(y, x, 256); serialusb.println(y[128]); serialusb.println(y[129]); serialusb.println(y[384]); serialusb.println(y[385]); // expected results: //y[128]is 8191; y[129] -8190 y[...
Read more

.htaccess - Matching full URL in RewriteCond -

-
i'm trying block post access site (and return 403), except 2 ip's , 1 url ( http://mydomain.com/about-us/contact-us/ ). here's have: rewritecond %{request_method} post rewritecond %{remote_addr} !=1.2.3.4 rewritecond %{remote_addr} !=4.3.2.1 rewritecond %{request_uri} !^http://mydomain.com/about-us/contact-us/$ rewriterule ^ / [f] these rules allowing access ip properly, contact page still not accessible. i'm not sure i'm using request_uri correctly? i've tried variations relative urls rewritecond %{request_uri} !^/about-us/contact-us$ , rewritecond %{request_uri} !^/about-us/contact-us/$ without luck. what doing wrong please? it looks me rule on file name specific. if relax bit, should work. made few other esthetic tweaks. give try: rewritecond %{request_method} post rewritecond %{remote_addr} !^1.2.3.4 rewritecond %{remote_addr} !^4.3.2.1 rewritecond %{request_uri} !about-us/contact-us rewriterule ^ - [f]
Read more