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adding a assembly file to project

naresh rana

Hi all

I want to add Asm file to a 'C' project.
Project has one '.c'and one '.h' file.

Assmbly file to be added is with '.a51' extension.only one routine is added to a51 file,which is called from main.A51 file is getting assembled successfully,but project is not getting compiled as whole.

decleration in main file is :

extern void delay_asm(unsigned char);


void main()
{
   .
   delay_asm(2);
   .
}


Assembly file is as given below

PR?delay_asm?delay_asm SEGMENT CODE

PUBLIC delay_asm

delay_asm:
   USING 0
   mov a,R7
rv:dec A
   Jnz rv
   RET

END

on project compilation:

warning L5:Code space overlap
From:0000H
To:0004H
warning L2:Refrence made to unresolved
external _delay_asm
Target not created.

This warnings where not generated before adding a51 file to project.

i am missing some thing small here,but any help would be appreciated.

Regards
Naresh

Parents
  • 0

    For such a simple loop why don't you stay in "C"

    void Delay (unsigned char Cycles)
{
    while (--Cycles);
}

    This function generates super efficient code:

    DELAY1: DJNZ R7,DELAY1

    If your real question is interfacing to assembler code, be aware of the register passing convention and function naming.

    Unless you state that your function is "alien", the actual assembly must be coded with an "_" (underscore) character preceeding the function name.

Reply
  • 0

    For such a simple loop why don't you stay in "C"

    void Delay (unsigned char Cycles)
{
    while (--Cycles);
}

    This function generates super efficient code:

    DELAY1: DJNZ R7,DELAY1

    If your real question is interfacing to assembler code, be aware of the register passing convention and function naming.

    Unless you state that your function is "alien", the actual assembly must be coded with an "_" (underscore) character preceeding the function name.

Children
  • 0 in reply to Bob Horeck

    For such a simple loop why don't you stay in "C"
    This function generates super efficient code
    Maybe and maybe not depending on brand, options and release. There is absolutely no guarantee that C will generate any specific code.

    Thus all timing must be in assembler.

    There is no end to the bitbanging and other time critical routines I have seen fall apart because the Compiler got upgraded/replaced.

    Erik

  • 0 in reply to erik malund

    If you really want accurate timing, use a timer.

    Even hand-tweaked assembler loops can fall apart the instant you change parts (12 clocks per instruction? 4? 2?), or oscillator frequency, or perhaps the external memory subsystem timing.

    Any function you put in software -- in whatever language -- will leave you potentialy liable for software maintenance when the environment changes in just the wrong way.