Re: [cc65] ASM to C help a n00b

On Thursday 27 May 2010, S M wrote:
> How can I have the following but in C?:

What exactly of this do you need in C?  I mean do you really need two 
names for the low and high part of the pointer to the `char0` for 
example?  Or is that just more convenient in ASM.

> I tried for example:
>
> unsigned char tile_buffer01 [8];
> unsigned char tile_buffer02 [8];
> unsigned char tile_buffer03 [8];
> unsigned char tile_buffer04 [8];
> unsigned char tile_buffer05 [8];
> unsigned char tile_buffer06 [8];
> unsigned char tile_buffer07 [8];
> unsigned char tile_buffer08 [8];
> unsigned char tile_buffer09 [8];
> unsigned char tile_buffer10 [8];
> unsigned char tile_buffer11 [8];
> unsigned char tile_buffer12 [8];
> unsigned char *tile_buffer [] =  {tile_buffer01, tile_buffer02,
> tile_buffer03, tile_buffer04, tile_buffer05, tile_buffer06,
> tile_buffer07, tile_buffer08, tile_buffer09, tile_buffer10,
> tile_buffer11, tile_buffer12};
>
> but it didn't work I get teste.c(29) Error: Constant expression
> expected teste.c(29): Warning: Converting integer to pointer without
> a cast .

That's not 29 lines so you don't get that error for just the shown 
source.  Just that compiles fine for me.  Here's what I used:

----

#include <stdint.h>

uint8_t tile_buffer01[8];
uint8_t tile_buffer02[8];
uint8_t tile_buffer03[8];
uint8_t tile_buffer04[8];
uint8_t tile_buffer05[8];
uint8_t tile_buffer06[8];
uint8_t tile_buffer07[8];
uint8_t tile_buffer08[8];
uint8_t tile_buffer09[8];
uint8_t tile_buffer10[8];
uint8_t tile_buffer11[8];
uint8_t tile_buffer12[8];

uint8_t *tile_buffers[] = {tile_buffer01, tile_buffer02, tile_buffer03,
    tile_buffer04, tile_buffer05, tile_buffer06, tile_buffer07,
    tile_buffer08, tile_buffer09, tile_buffer10, tile_buffer11,
    tile_buffer12};

int main(void)
{
    return 0;
}

----

Again the question: Is that really what you need in C?  Do you change 
the content of the pointer array within the program?  If not then::

  uint8_t tile_buffers[12][8];

would be much shorter.  Even if the pointer table to the individual 
buffers is needed at runtime I would write it that way because 
enumerating variable names is a "code smell" indicating that you really 
wanted an array in the first place.

Ciao,
	Marc 'BlackJack' Rintsch
-- 
“Think of it!  With VLSI we can pack 100 ENIACS in 1 cm².”
                                         -- Alan J. Perlis

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