StrNCpyAsm, Assembly Language

;StrNCpyAsm - copy zero terminated string2 to zero terminated string1,
; but copy no more than count (parameter) characters
; or the length of string2, whichever comes first
; entry: - addStr1 contains the address of string1
; - addStr2 contains the address of string2
; - count contains the max number of characters to copy
; exit: NONE (no return value so do not use edi to return an address)
; Note: StrNCpyAsm does not zero terminate the copied string
; unless the 0 is within count characters copied.
; example1: char str1[]= {''h'',''e'',''l'',''l'',''o'','' '',''w'',''o'',''r'',''l'',''d'',0};
; char str2[]= {''G'',''o'',''o'',''d'',''-'',''b'',''y'',''e'',0};
; StrNCpyAsm(str1,str2,4);//terminating 0 not copied since only 4 characters copied
; ;//and terminating 0 not within the 4 characters
; after copy str1 contains: ''G'',''o'',''o'',''d'',''o'','' '',''w'',''o'',''r'',''l'',''d'',0
; example2: use str1 and str2 from example1
; StrNCpyAsm(str1,str2,9); //terminating 0 copied since terminating 0
; //within 9 characters copied
; str1 contains: ''G'',''o'',''o'',''d'',''-'',''b'',''y'',''e'',0,''l'',''d'',0
; example3: use str1 and str2 from example1
; StrNCpyAsm(str1,str2,20);//copy 20 characters upto and including 0,
; //whichever comes first
; //only 9 characters including 0 copied
; after copy str1 contains: ''G'',''o'',''o'',''d'',''-'',''b'',''y'',''e'',0,''l'',''d'',0
; The above is how you would call StrNCpyAsm from C++.
; To call StrNCpyAsm from an asm function use:
; push 20 ;max num of characters to copy
; push str2Add ;address of string 2
; push str1Add ;address of string 1
; call StrNCpyAsm
; ;no add esp, 12 needed because stack cleaup automatically done
;Do not use a loop in this function.
;Choose 2 instructions from the following string instructions to use:
; rep, repe, repne, movsb,stosb,cmpsb,scasb
; hint1: use StrLenAsm to get the number of characters in str2
; hint2: the length returned by StrLenAsm does not include terminating 0
; hint3: copy the lesser of the length of the string (including terminating 0)
; or count characters
;copy to ecx the lesser of count or the length of string2 (including terminating 0)
; Please note for the above, you need the length of string2 including terminating 0.
; StrLenAsm returns the length not including terminating 0
;populate esi and edi with the correct values
;clear the direction flag
;use rep and movsb to copy

StrNCpyAsm PROC uses eax esi edi ecx , ;save registers used
addStr1:DWORD, ;address of string1
addStr2:DWORD, ;address of string2
count:DWORD ;max chars to copy
Posted Date: 12/6/2012 11:39:50 PM | Location : United States

Related Discussions:- StrNCpyAsm, Assignment Help, Ask Question on StrNCpyAsm, Get Answer, Expert's Help, StrNCpyAsm Discussions

Write discussion on StrNCpyAsm
Your posts are moderated
Related Questions
This unit introduces the topic of evaluating interactive products. It is a short unit as evaluation is discussed in more detail in Block 4. Its brevity should give you additional t

Why is the capability to relocate processes desirable?

The Pentium Pro    Introduced in the year 1995, the Pentium Pro reflected  still  more  design  breakthroughs.  The Pentium Pro may process 3 instructions in a single clock cy

given a sentence, find the number of times a particular character or word appear. the sentence is to be entered by the user

Develop an assembly language program for the system and simulate it using MPLAB. From this produce a demo program (in Assembly language) that will run on the MatrixMultimedia Devel

The problem to be solved and implemented with an ARM assembly language program You are asked to do some image processing on an image composed of characters shaped in For exa


AAD: ASCII Adjust for Division though the names of these 2 instructions (AAM and AAD) seem to be same, there is many difference between their functions. The AAD instruction conver

Entering a Program In this section, we will explain the procedure for entering a small program on IBM PC with DOS operating system. Assume a program of addition of 2 bytes, as

Internal Hardware-Interrupts Internal hardware-interrupts are the outcome of sure situations that occur during the execution of a program, for example. Divide by 0. The interru