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Memcpy procedure for 80188 embedded system

Wed, 29 Oct 2003 10:15:17 -0700

Hi

I need to write a "memcpy" procedure in assembly for an embedded system running on an 80188 microprocessor. Memcpy() copies n bytes from memory area s2 to s1 and returns s1. It is called in C code as follows:

void *memcpy(void *s1, const void *s2, size_t n)

I am very new to assembly programming and is hoping for some advice how this can be done. Btw, is there a compiler which translate C code into assembly?

Any advice is very much appreciated. Thank you.

Regards
Wilson

Re: Memcpy procedure for 80188 embedded system

Wed, 29 Oct 2003 10:26:57 -0700

: Hi, I need to write a "memcpy" procedure in assembly

  MOV  SI,OFFSET SOURCE (DS:SI = source addr) (x86 real mode addressing)
  MOV  DI,OFFSET DESTINATION (ES:DI = destination address)
  MOV  CX,SIZE
  REPZ MOVSB

That's your standard .asm memory copy for x86.
Maybe others can add more to this...

Bitdog

Re: Memcpy procedure for 80188 embedded system

Thu, 30 Oct 2003 15:36:34 -0700

: : Hi, I need to write a "memcpy" procedure in assembly
:
:

:   MOV  SI,OFFSET SOURCE (DS:SI = source addr) (x86 real mode addressing)
:   MOV  DI,OFFSET DESTINATION (ES:DI = destination address)
:   MOV  CX,SIZE
:   REPZ MOVSB
:

: That's your standard .asm memory copy for x86.
: Maybe others can add more to this...
:
: Bitdog
:
:
:
Most compilers have a commandline switch that will output their assembly code generation to a file; the best compilers, however, generate AT&T syntax. Borland's free commandline C++ 5.5 outputs assembly by specifying -s, for example. It's output is not always as high-quality as some of the UNIX-ported compilers, most notably, LCC (Little C Compiler, Navia, http://www.cs.virginia.edu/~lcc-win32/ ), which only generates AT&T syntax.

Obviously, the programmers of UNIX knew there were shift and caps lock keys, since the name UNIX is capitalized. From then on in, they seemed oblivious to them.