On Wed, 1 Mar 2006, Wouter van Ooijen wrote:

>>> But how else would you write a bit-banged UART in a HLL without 
>>> using timers?
>>
>> Inline assembly ... C can do it.
>
> In-line assembly is a way to combine HLL and assembly that is often more
> convenient than using separate C and asm files. But it is not HLL. If
> you disagree I'll rephrase: how do you do it in a portable way (one
> source for PIC and an as-yet-undifined chip, but one that is supported
> by the HLL)?

// setup (can include setup file)

// define ONE
#define PIC_IMPLEMENTATION_A
// #define PIC_IMPLEMENTATION_B

// ****** Implementation start

// Function foo() does something
void foo(void) {
 	unsigned char a, b = 2, c = 3;

// ****** PIC IMPLEMENTATION
#ifdef __PIC

#  ifdef PIC_IMPLEMENTATION_A
#  define _SECTION_FOO_SEEN
 	--c; // C

 	_asm

 	movf	_b
 	addwf	_c,w
 	movwf	a

 	_endasm;
#  endif

#  ifdef PIC_IMPLEMENTATION_B
#  define _SECTION_FOO_SEEN

 	_asm

 	movf	_c
 	addwf	_b,w
 	movwf	a

 	_endasm;
#  endif

#endif

// ****** MCS51 implementation
#ifdef _MCS51
#define _SECTION_FOO_SEEN

 	++b; // C
 	_asm

 	mov	A, _c
 	add	_b
 	mov	_a, A

 	_endasm;

#endif

// ****** PORTABLE C IMPLEMENTATION
#ifdef _POSIX
#define _SECTION_FOO_SEEN

 	a = b * c; // pure C

#endif

} // foo()

...

#ifndef _SECTION_FOO_SEEN
#  error "Could not compile foo (_SECTION_FOO_SEEN undefined)"
#endif

Peter
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