C array reference from asm code with XA ?

[goyo]

Hi,
Is it possible to use a C array reference from asm code ? (or the opposite) I wrote the following asm code but it doesn't works .

c code

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signed int map_y_index_lookup_table[] = {0,64,128,192,256,320,384,448,512,576,640,704,768,832,896,960,1024,1088};

asm code

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.global _map_y_index_lookup_table ; => 5177:Syntax error 

[Dbug]

The easiest is to do the opposite:

In you assembler code:

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_map_y_index_lookup_table .word 0,64,128,192,256,320,384,448,512,576,640,704,768,832,896,960,1024,1088

In your C code:

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extern int map_y_index_lookup_table[];

The advantage of declaring stuff in the assembler module over C is that:
- You can align data where you want
- You can declare variables in zero page

The only important thing to remember is that in the assembler module the symbols need to start by a _ character so they have global export.

[goyo]

Thank you Dbug ! I ll do like that

[goyo]

so I would like to set an array with negatives values in 8 bits,

what is the technic and the good practice to do this ?

is it possible for the C to read these values ?

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_tile_delta_y_step_lookup_table
.byt -80,-40,0,40,80

in main.c

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extern char tile_delta_y_step_lookup_table[]; 

it said : syntax error (at assembling phase.)

[Dbug]

Yeah that's unfortunately not something supported by XA, I wanted to fix that, never had the time.
I basically had to cheat by adding 255, like .byt 255-80

[ibisum]

If its constants, and you need certainty, why not hex?

B0,D8,00,28,50

[Dbug]

When working with natural values signed decimal is a good choice, in the same way as binary works nicely for bitmaps, and hexadecimal nice for addresses.

[goyo]

Thank you Dbug , I didn't know two's complement, I'm discovering