Programming Forums > Application Development > Assembly

Mjordan2nd · Feb 1st, 2005, 10:09 PM

I basically used DI instead of EDI. I don't know what assembler you're using, but in NASM, [DI] means the value that's being pointed to by DI. If DI holds the memory address of the first character in the string, then [DI] basically is the value of the first character. The WORD keyword basically explicitly tells the compiler that we're working with a 16-bit value.

oxyi · Feb 2nd, 2005, 1:04 AM

ahh roger that , let me tinker with it a bit, and report back what i have

thanks a lot mjordan2nd

lostcauz · Feb 2nd, 2005, 1:47 AM

Here's another using MASM.

(Toggle Plain Text)

; Count vowels, MASM 
; compiled using "console assemble and link" in Qeditor
.486                                    
.model flat, stdcall                    
option casemap :none                   
 
include \masm32\include\windows.inc    
include \masm32\macros\macros.asm       
include \masm32\include\masm32.inc
include \masm32\include\kernel32.inc
includelib \masm32\lib\masm32.lib
includelib \masm32\lib\kernel32.lib

.data
    str1 db "aeiouAEIOU", 0
    str2 db "coUntsomevowEls", 0
    
.code          
             
start:   
    mov ecx, offset str1     ; load vowels
    mov edx, offset str2     ; load string
    xor esi, esi             ; zero vowel position counter
    xor edi, edi             ; zero string position counter
    xor ebx, ebx             ; number of vowels in word
l1: mov al, [ecx+esi]        ; begin loop, update vowel position
    cmp al, [edx+edi]        ; update string position
    jne @f                   ; not a vowel
    inc ebx                  ; is a vowel, count it
@@: inc esi                  ; increment vowel array position
    test al, al              ; check for terminator
    jne l1                   ; check all vowels
    inc edi                  ; next letter in word being checked
    cmp edi, [sizeof str2-1] ; test for end of string
    je  @f                   ; end of string
    xor esi, esi             ; reset vowel position counter
    jmp l1                   ; loop
@@: print str$(ebx)          ; print result to console
    exit
    
end start

oxyi · Feb 2nd, 2005, 10:20 PM

what is the difference between MASM and Microsoft Visual .Net,
because the way you coded is very different from what MJordan2nd wrote.

when I try something like

str1 db "aeiouAEIOU", 0
str2 db "coUntsomevowEls", 0

in visual.net, it gives me some kidn error.. is there a different syntex ?

Is MASM for like more advanced assembly coder? Thanks !

Mjordan2nd · Feb 2nd, 2005, 10:23 PM

Well, the idea is the same. He's using a string that stores all the vowels and looping through it, checking each time. His way is definitely more elegant than mine.

oxyi · Feb 2nd, 2005, 10:30 PM

Yap i got his idea, but was having problem implementing that.

So he store the all vowels in a string, then compare the vowels with a given string.
but I was having problem of putting

str1 db "aeiouAEIOU", 0 into the way you coded,
and i don't really get whats [edx+edi] does.

Btw thanks for a very nice commented code, it helps a lot

lostcauz · Feb 3rd, 2005, 3:32 AM

MASM is the Microsoft assembler. http://www.masm32.com/

Concerning [edx+edi], notice before entering the loop I xor'ed some registers with themselves. This sets the register to zero. I also pointed ecx and edx to the beginning of the 2 string arrays. ecx is pointing to the first character of the vowel array or 'a'. edx points to the first character in the other string which is 'c'. So when you first enter the loop, ecx is pointing to the first character (index zero) + esi, which is equal to zero, therefore resulting in the character 'a'. Since edi is also zero the same is true for edx. It points to the first character, 'c'.

After passing through the loop notice esi is incremented until the end of the vowel string. Now we are able to move to the next character in our other string. After incrementing edi the statement [edx+edi] may be broken down to [beginning of array + 1] which of course is 'o'. esi is reset to zero and we loop through the vowels once more. Since 'o' is a vowel, the vowel counting variable will be incremented. In this case I used ebx.

oxyi · Feb 4th, 2005, 4:12 AM

Ahhh got it, thanks Lostcauz !!

Very nice explaination

oxyi · Feb 8th, 2005, 12:17 AM

Hi,

I am doing binary search now. But have some question doing so.

If i remembered how to do binary search correctly, it is like,
given a key in a pre-sorted array, then repeatedly dividing the search interval in half. Begin with an interval covering the whole array. If the value of the search key is less than the item in the middle of the interval, narrow the interval to the lower half. Otherwise narrow it to the upper half. Repeatedly check until the value is found or the interval is empty.

Now to the actualy code of implentation.

But I am not sure how do i go about doing this,

(Toggle Plain Text)


void binarySearch(apvector <int> &array, int lowerbound, int upperbound, int key)
{
       int position;
       int comparisonCount = 1;     //variable used to count the comparisons.

       // calculate the first search position.
       position = ( lowerbound + upperbound) / 2;

       while((array[position] != key) && (lowerbound <= upperbound))
       {
              comparisonCount++;
              if (array[position] > key)                // if the value in the search position..
             {                                                       // is greater than the number for ?/b>
                    upperbound = position - 1;    // which we are searching, change ..
             }                                                       // upperbound to the search position?/b>
             else                                                 // minus one.
            {                                                        // Else, change lowerbound to search..
                   lowerbound = position + 1;     // position plus one.
             }
             position = (lowerbound + upperbound) / 2;
       }
      if (lowerbound < = upperbound)
      {
            cout<< "The binary search found the number after " << comparisonCount 
                   << " comparisons.\n";
            cout<< "The number was found in array subscript "<< position<<endl<<endl;      
       }      
       else
             cout<< "Sorry, the number is not in this array.  The binary search made "
                   <<comparisonCount << " comparisons.";
       return;
}

so far, i got this,

(Toggle Plain Text)

int  binarySearch(int *array, int _size, int key, int *count)
{
	// isFound is the boolean result of search.
	int isFound=0;
	__asm {
	
	  push esi 
	  push edi
      push eax 
      push ebx 
      push ecx
	  push edx

	  mov esi, array //esi is the address of the input array
	  mov edi, count

My problem is, im not sure how would i go about divide the esi into half and
compared the value thats in there , or store the upperbound or lowerbound..

thanks again

oxyi · Feb 8th, 2005, 7:51 PM

I kinda knew how to do it, but how would u
take a floor of a number, say 7/3 = 2.5, , but I only want 2 ?

because I want to find the middle of the array,
then somehow determine the end of the array, but
I am not quite sure how to accomplish that? anyone ?

Feb 1st, 2005, 10:09 PM	#11
Mjordan2nd The Supreme Ruler Join Date: May 2004 Location: Houston Posts: 1,476 Rep Power: 6	I basically used DI instead of EDI. I don't know what assembler you're using, but in NASM, [DI] means the value that's being pointed to by DI. If DI holds the memory address of the first character in the string, then [DI] basically is the value of the first character. The WORD keyword basically explicitly tells the compiler that we're working with a 16-bit value. __________________ "Every gun that is made, every warship launched, every rocket signifies, in the final sense, a theft from those who hunger and are not fed, from those who are cold and are not clothed. The world in arms is not spending money alone. It is spending the sweat of its laborers, the genius of its scientists, the hopes of its children." - Dwight D. Eisenhower

Feb 2nd, 2005, 1:47 AM	#13
lostcauz Hobbyist Programmer Join Date: Nov 2004 Location: 1691 miles East of L.A. Posts: 159 Rep Power: 4	Here's another using MASM. (Toggle Plain Text) ; Count vowels, MASM ; compiled using "console assemble and link" in Qeditor .486 .model flat, stdcall option casemap :none include \masm32\include\windows.inc include \masm32\macros\macros.asm include \masm32\include\masm32.inc include \masm32\include\kernel32.inc includelib \masm32\lib\masm32.lib includelib \masm32\lib\kernel32.lib .data str1 db "aeiouAEIOU", 0 str2 db "coUntsomevowEls", 0 .code start: mov ecx, offset str1 ; load vowels mov edx, offset str2 ; load string xor esi, esi ; zero vowel position counter xor edi, edi ; zero string position counter xor ebx, ebx ; number of vowels in word l1: mov al, [ecx+esi] ; begin loop, update vowel position cmp al, [edx+edi] ; update string position jne @f ; not a vowel inc ebx ; is a vowel, count it @@: inc esi ; increment vowel array position test al, al ; check for terminator jne l1 ; check all vowels inc edi ; next letter in word being checked cmp edi, [sizeof str2-1] ; test for end of string je @f ; end of string xor esi, esi ; reset vowel position counter jmp l1 ; loop @@: print str$(ebx) ; print result to console exit end start ; Count vowels, MASM ; compiled using "console assemble and link" in Qeditor .486 .model flat, stdcall option casemap :none include \masm32\include\windows.inc include \masm32\macros\macros.asm include \masm32\include\masm32.inc include \masm32\include\kernel32.inc includelib \masm32\lib\masm32.lib includelib \masm32\lib\kernel32.lib .data str1 db "aeiouAEIOU", 0 str2 db "coUntsomevowEls", 0 .code start: mov ecx, offset str1 ; load vowels mov edx, offset str2 ; load string xor esi, esi ; zero vowel position counter xor edi, edi ; zero string position counter xor ebx, ebx ; number of vowels in word l1: mov al, [ecx+esi] ; begin loop, update vowel position cmp al, [edx+edi] ; update string position jne @f ; not a vowel inc ebx ; is a vowel, count it @@: inc esi ; increment vowel array position test al, al ; check for terminator jne l1 ; check all vowels inc edi ; next letter in word being checked cmp edi, [sizeof str2-1] ; test for end of string je @f ; end of string xor esi, esi ; reset vowel position counter jmp l1 ; loop @@: print str$(ebx) ; print result to console exit end start __________________ -- lostcauz Stepped in what?... Behind whose barn?... I didn't even know they had a cow!

Feb 2nd, 2005, 10:20 PM	#14
oxyi Newbie Join Date: Jan 2005 Posts: 17 Rep Power: 0	what is the difference between MASM and Microsoft Visual .Net, because the way you coded is very different from what MJordan2nd wrote. when I try something like str1 db "aeiouAEIOU", 0 str2 db "coUntsomevowEls", 0 in visual.net, it gives me some kidn error.. is there a different syntex ? Is MASM for like more advanced assembly coder? Thanks ! Last edited by oxyi; Feb 2nd, 2005 at 10:27 PM.

Feb 2nd, 2005, 10:23 PM	#15
Mjordan2nd The Supreme Ruler Join Date: May 2004 Location: Houston Posts: 1,476 Rep Power: 6	Well, the idea is the same. He's using a string that stores all the vowels and looping through it, checking each time. His way is definitely more elegant than mine. __________________ "Every gun that is made, every warship launched, every rocket signifies, in the final sense, a theft from those who hunger and are not fed, from those who are cold and are not clothed. The world in arms is not spending money alone. It is spending the sweat of its laborers, the genius of its scientists, the hopes of its children." - Dwight D. Eisenhower

Feb 3rd, 2005, 3:32 AM	#17
lostcauz Hobbyist Programmer Join Date: Nov 2004 Location: 1691 miles East of L.A. Posts: 159 Rep Power: 4	MASM is the Microsoft assembler. http://www.masm32.com/ Concerning [edx+edi], notice before entering the loop I xor'ed some registers with themselves. This sets the register to zero. I also pointed ecx and edx to the beginning of the 2 string arrays. ecx is pointing to the first character of the vowel array or 'a'. edx points to the first character in the other string which is 'c'. So when you first enter the loop, ecx is pointing to the first character (index zero) + esi, which is equal to zero, therefore resulting in the character 'a'. Since edi is also zero the same is true for edx. It points to the first character, 'c'. After passing through the loop notice esi is incremented until the end of the vowel string. Now we are able to move to the next character in our other string. After incrementing edi the statement [edx+edi] may be broken down to [beginning of array + 1] which of course is 'o'. esi is reset to zero and we loop through the vowels once more. Since 'o' is a vowel, the vowel counting variable will be incremented. In this case I used ebx. __________________ -- lostcauz Stepped in what?... Behind whose barn?... I didn't even know they had a cow!

Feb 2nd, 2005, 1:04 AM	#12
oxyi Newbie Join Date: Jan 2005 Posts: 17 Rep Power: 0	ahh roger that , let me tinker with it a bit, and report back what i have thanks a lot mjordan2nd

Feb 2nd, 2005, 10:30 PM	#16
oxyi Newbie Join Date: Jan 2005 Posts: 17 Rep Power: 0	Yap i got his idea, but was having problem implementing that. So he store the all vowels in a string, then compare the vowels with a given string. but I was having problem of putting str1 db "aeiouAEIOU", 0 into the way you coded, and i don't really get whats [edx+edi] does. Btw thanks for a very nice commented code, it helps a lot

Feb 4th, 2005, 4:12 AM	#18
oxyi Newbie Join Date: Jan 2005 Posts: 17 Rep Power: 0	Ahhh got it, thanks Lostcauz !! Very nice explaination

Feb 8th, 2005, 12:17 AM	#19
oxyi Newbie Join Date: Jan 2005 Posts: 17 Rep Power: 0	Hi, I am doing binary search now. But have some question doing so. If i remembered how to do binary search correctly, it is like, given a key in a pre-sorted array, then repeatedly dividing the search interval in half. Begin with an interval covering the whole array. If the value of the search key is less than the item in the middle of the interval, narrow the interval to the lower half. Otherwise narrow it to the upper half. Repeatedly check until the value is found or the interval is empty. Now to the actualy code of implentation. But I am not sure how do i go about doing this, (Toggle Plain Text) void binarySearch(apvector <int> &array, int lowerbound, int upperbound, int key) { int position; int comparisonCount = 1; //variable used to count the comparisons. // calculate the first search position. position = ( lowerbound + upperbound) / 2; while((array[position] != key) && (lowerbound <= upperbound)) { comparisonCount++; if (array[position] > key) // if the value in the search position.. { // is greater than the number for ?/b> upperbound = position - 1; // which we are searching, change .. } // upperbound to the search position?/b> else // minus one. { // Else, change lowerbound to search.. lowerbound = position + 1; // position plus one. } position = (lowerbound + upperbound) / 2; } if (lowerbound < = upperbound) { cout<< "The binary search found the number after " << comparisonCount << " comparisons.\n"; cout<< "The number was found in array subscript "<< position<<endl<<endl; } else cout<< "Sorry, the number is not in this array. The binary search made " <<comparisonCount << " comparisons."; return; } void binarySearch(apvector <int> &array, int lowerbound, int upperbound, int key) { int position; int comparisonCount = 1; //variable used to count the comparisons. // calculate the first search position. position = ( lowerbound + upperbound) / 2; while((array[position] != key) && (lowerbound <= upperbound)) { comparisonCount++; if (array[position] > key) // if the value in the search position.. { // is greater than the number for ?/b> upperbound = position - 1; // which we are searching, change .. } // upperbound to the search position?/b> else // minus one. { // Else, change lowerbound to search.. lowerbound = position + 1; // position plus one. } position = (lowerbound + upperbound) / 2; } if (lowerbound < = upperbound) { cout<< "The binary search found the number after " << comparisonCount << " comparisons.\n"; cout<< "The number was found in array subscript "<< position<<endl<<endl; } else cout<< "Sorry, the number is not in this array. The binary search made " <<comparisonCount << " comparisons."; return; } so far, i got this, (Toggle Plain Text) int binarySearch(int array, int _size, int key, int count) { // isFound is the boolean result of search. int isFound=0; __asm { push esi push edi push eax push ebx push ecx push edx mov esi, array //esi is the address of the input array mov edi, count int binarySearch(int array, int _size, int key, int count) { // isFound is the boolean result of search. int isFound=0; __asm { push esi push edi push eax push ebx push ecx push edx mov esi, array //esi is the address of the input array mov edi, count My problem is, im not sure how would i go about divide the esi into half and compared the value thats in there , or store the upperbound or lowerbound.. thanks again

Feb 8th, 2005, 7:51 PM	#20
oxyi Newbie Join Date: Jan 2005 Posts: 17 Rep Power: 0	I kinda knew how to do it, but how would u take a floor of a number, say 7/3 = 2.5, , but I only want 2 ? because I want to find the middle of the array, then somehow determine the end of the array, but I am not quite sure how to accomplish that? anyone ?

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Programming Forums > Application Development > Assembly

How do i convert this code into assembly ??