tilemap_at.c

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/*****************************************************************************
 * ugBASIC - an isomorphic BASIC language compiler for retrocomputers        *
 *****************************************************************************
 * Copyright 2021-2026 Marco Spedaletti (asimov@mclink.it)
 *
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/****************************************************************************
 * INCLUDE SECTION 
 ****************************************************************************/
 
#include "../../ugbc.h"
 
/****************************************************************************
 * CODE SECTION 
 ****************************************************************************/
 
extern char DATATYPE_AS_STRING[][16];

/* <usermanual>
@keyword TILEMAP AT
 
@english
This function allows to know which is the tile present in a tilemap, 
given the coordinates of the tile itself. If the tilemap has more than
one layer, the first layer will be returned. If you need to retrieve the
tile of a different level, you have to indicate the layer with the ''LAYER'' 
keyword.
 
@italian
Questa funzione permette di conoscere quale sia il tile di una mappa, 
date le coordinate del tile stesso. Se la mappa ha più di un livello, 
verrà restituito il primo livello. Se si deve recuperare il tile 
di un livello diverso, si deve indicare con la parola chiave ''LAYER''.
 
@syntax = TILEMAP [LAYER layer] map AT([x],[y])
 
@example tile = TILEMAP map AT(0,0)
@example tile = TILEMAP map LAYER 2 AT(0,0)
 
@target all
</usermanual> */
Variable * tilemap_at( Environment * _environment, char * _tilemap, char * _x, char * _y, char * _layer ) {
 
    Variable * tilemap = NULL;
    Variable * x = NULL;
    Variable * y = NULL;
    Variable * layer = NULL;
    Variable * frame = variable_temporary( _environment, VT_BYTE, "(frame)" );
 
    tilemap = variable_retrieve( _environment, _tilemap );
    if ( tilemap->type != VT_TILEMAP ) {
        CRITICAL_TILEMAP_HEIGHT_NO_TILEMAP( _tilemap );
    }
 
    Variable * width = variable_temporary( _environment, VT_BYTE, "(width)" );
    variable_store( _environment, width->name, tilemap->mapWidth );
    Variable * height = NULL;
    if ( _layer ) {
        height = variable_temporary( _environment, VT_BYTE, "(height)" );
        variable_store( _environment, height->name, tilemap->mapHeight );
    }
 
    x = variable_retrieve_or_define( _environment, _x, VT_BYTE, 0 );
    y = variable_retrieve_or_define( _environment, _y, VT_BYTE, 0 );
    if ( _layer ) {
        layer = variable_retrieve_or_define( _environment, _layer, VT_BYTE, 0 );
    }
 
    Variable * mul = variable_mul( _environment, width->name, y->name );
    Variable * offset = variable_add( _environment, mul->name, x->name );
    if ( layer ) {
        Variable * mul2 = variable_mul( _environment, width->name, height->name );
        Variable * mul3 = variable_mul( _environment, mul2->name, layer->name );
        variable_move( _environment, variable_add( _environment, mul3->name, offset->name )->name, offset->name );
    }
    cpu_move_8bit_indirect2_16bit( _environment, tilemap->realName, offset->realName, frame->realName );
 
    return frame;
 
}