Hi everyone,

I am trying to hand compile a C code to assembly language.

im having trouble to code only this part of my C code



here is the assembly language code i have written
dividend = a1
divisor = a2




hope anybody who read this understand my problem. Can anybody plz help me on this.

I would use jump if equal / jump if not equal.

http://209.85.165.104/search?q=cache:6zcb-...;cd=1&gl=us
check out page 8.

This && !(divisor & 0x40000000 ) part of the condition can be greatly optimized by using the TEST instruction like this.
Even the comparison can be reduced. Have a look at how I am comparing(testing) only 1 byte instead of all 4 bytes.
(Works only for 32-bit ASM)

Thanks guys for the support,

I am still trying to figure out how to write the while loop in assembly language.



the part NOT clear to me is the "!(divisor & 0x400000000)"

Can anybody tell me wats this part doing, i know its ANDing the divisor with 0x40h, (wats ! of the result)




here i have used tst which changes the CPSR flage (updates the flage) But iam not clear of wat u to use "bne" or "beq"

born2c0de, thanks for the help, but i havent done (not studied yet) "jmp" so dont know wats happening in ur code.

Hope somebody will help me more

Thanks

This post has been edited by eudos: 17 Sep, 2007 - 01:35 PM

I posted a link that describes in detail the jump (jmp) command. It's on page 8.

jmp is an unconditional jump
jz is 'jump if zero'
jle is 'jump if less than or eqaul to'

LOOP_BODY, LOOP_BEGIN and LOOP_END are labels, simply put they can be related to procedure calls, except these just jump straight to the next line of code, but unlike procedures these have no end point, unless the program is given another jump command it will just continue going sequencially through the rest of your code,

JMP and its cousins modify your program counter, line pointer or whatever you want to call it, to point to the next line of code it should execute. these jump points are given by the labels.

eg if you say , it will jump to the first line of your code

just like if your program looked like

line 0100 will cause the program to jump back to line 0000

Dont take my word as gold, its been a year + since ive done this stuff, play with it, its the best way to learn.

have fun

hehe someone got there first...

Just a little FYI. You can generally get your C compiler to output Assembly. Especially if you are not using library function (which just come out as calls in the assembly code).

The other thing you can do is write the code, compile and then use a debugger or disassembler to view the compiled code. -- I learned a GREAT DEAL of assembly this way. I also learned a great deal about C this way.

thanks guys. i have fixed the problem now..here is the code i used.



i use a debugger to fix the code, and also i am using the ARM architecture as a target mem.