Generating DA A via C code.

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Read-Only Author Sarang Patki Posted 23-Feb-2005 16:07 GMT Toolset C51	Generating DA A via C code. Sarang Patki Hi all. I am facing this problem. If I am using following syntax, logically it is ok, but it is generating a wrong asm code via keil C51. Problem 1 ACC = ACC + B; This statement works fine with C. Now I thought it will generate ADD A, B; but it is generating MOV A, B; ADD A, B; Problem 2 his C code also involving ACC without my wish. ACC = z; B = 0; if(ACC<100) ... his is generating following asm code MOV A, z(0X0A) CLR A; MOV B, A; this is not what i want. if I interchange the first 2 lines it works OK. Why so? Problem 3 I want the DA A command to take place in my code after the addition what I will have to do? As I want to convert the result in decimal and form that I want to show it on LCD. (DEC to ASCII is quite simple) I tried lot of C code variations which show correct result as far as only C is concerned but they arte generating absurd AS code and nothing is working. Please suggest something.

Read-Only Author Jon Ward Posted 23-Feb-2005 16:15 GMT Toolset C51	RE: Generating DA A via C code. Jon Ward Your problem is that you are using a C compiler but you are writing assembly code. This is like using a chainsaw to perform dental surgery. The compiler has to use the accumulator to do its job. When you write code that tries to manipulate the accumulator, you will ultimately fail. The reason is because the compiler uses the accumulator. So, if the compiler uses the accumulator and you also use the accumulator in your C program, you will corrupt the code the compiler is trying to generate. If you want to write assembly code, use the assembler. Jon

Read-Only Author Sarang Patki Posted 23-Feb-2005 16:40 GMT Toolset C51	RE: Generating DA A via C code. Sarang Patki OK. This means compiler is unnecessarily increasing the no. of instructions. isn't it? Anyway thanks for that. What about generating DA A instruction via C code.

Read-Only Author Stefan Duncanson Posted 23-Feb-2005 16:53 GMT Toolset C51	RE: Generating DA A via C code. Stefan Duncanson As Jon says, forget about assembler. You are using a 'C' compiler. This should give you a starting point: int a=5,b=7; char buff[10]; a+=b; sprintf(buff,"%d",a); LCD_print(buff);

Read-Only Author erik malund Posted 23-Feb-2005 17:16 GMT Toolset C51	RE: Generating DA A via C code. erik malund What about generating DA A instruction via C code. What about hammering a nail in with a screwdriver? ... same thing Erik

Read-Only Author Andrew Neil Posted 23-Feb-2005 17:38 GMT Toolset C51	RE: Generating DA A via C code. Andrew Neil "OK. This means compiler is unnecessarily increasing the no. of instructions. isn't it?" No. It means that you are using totally the wrong tool. Using a high level language means that you have delegated the choice of the specific machine instructions & registers to the compiler. If you need to use specific machine instructions & registers then *you must* use assembler! You can't have it both ways; you can't have your cake and it eat it! There is no way to force any 'C' compiler to generate any specific machine instruction(s).** That's the whole point: http://www.8052.com/forum/read.phtml?id=68927

Read-Only Author Sarang Patki Posted 24-Feb-2005 05:02 GMT Toolset C51	RE: Generating DA A via C code. Sarang Patki Thanks to all.

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