assembly - frequency table with ascii index and decimal value -

i write code computer each character in string's frequency, , array index 0 255, ascii index , value frequency character appear.

i compare each character in string , add 1 in array each time.

but cannot find error count seem not right(too large)?

the result should

but result's count large.

the error comes in l1 loop , don't know why loop cause large number.

please give me guidance wrong.

thank reading.

include irvine32.inc  .data     teststring byte "aaebdcfbbc",0      freqtable dword 256 dup(0)     prompt byte 0dh, 0ah, 0     prompt1 byte ": ", 0 .code      freq proc uses edi,         tstring:ptr byte,          ftable:ptr dword      mov eax,0     cld      mov edi,ftable       mov ecx,256     rep stosd;initialize ftable 0       mov edi,ftable;reset edi position     mov edx,tstring     mov ecx,sizeof tstring;element number     dec ecx;remove null character      l1:     mov al,[edx]  ;character value     inc edx     ;index ++     inc dword ptr[edi+eax] ;value ++         loop l1     ret freq endp   main proc main endp     invoke freq, addr teststring, addr freqtable     mov ecx, 256     mov ebx, 0     mov edi,offset freqtable     mov eax, 0      l1:         call writehex;index         mov  edx,offset prompt1         call writestring;": "          mov ebx, [edi + eax]         xchg eax,ebx         call writeint         xchg eax,ebx         mov  edx,offset prompt         call writestring;endline         inc eax;index ++         loop l1         ;ret end main 

from first glance code seems right. find line mov ecx,sizeof tstring little suspicious, make sure returns size of string - fear returns size of pointer. (but should make count less not more.)

also, during write loop, make sure various functions call don't change registers depend on, particularly eax in danger.

otherwise should use debugger check whether produced result correct can tell whether it's freq function or printing loop that's faulty. having found that, should step through part see goes wrong.

update

your freqtable apparently made of dwords (4 bytes each) indexing uses 1-byte units. you'll have change inc dword ptr[edi+eax] inc dword ptr[edi+eax*4] in counting loop, , mov ebx, [edi + eax] mov ebx, [edi + eax*4] in printing loop.