on_goto.c

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/*****************************************************************************
 * ugBASIC - an isomorphic BASIC language compiler for retrocomputers        *
 *****************************************************************************
 * Copyright 2021-2026 Marco Spedaletti (asimov@mclink.it)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
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 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *----------------------------------------------------------------------------
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 * (la "Licenza"); è proibito usare questo file se non in conformità alla
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 * Se non richiesto dalla legislazione vigente o concordato per iscritto,
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/****************************************************************************
 * INCLUDE SECTION 
 ****************************************************************************/
 
#include "../../ugbc.h"
 
/****************************************************************************
 * CODE SECTION 
 ****************************************************************************/

/* <usermanual>
@keyword ON...GOTO
 
@english
This command is used to force a unconditional jump to a pre-defined position when a 
specific expression is calculated. The choice is done against several positions,
and it depends on what value is held by the expression at the time it is spotted.
 
To work properly, the expression must have a value from 1 up to the number of 
the highest possible destination. If the expression has a value of 0 or 
greater than the highest possibile destination, no jump will be performed.
 
@italian
Questo comando viene utilizzato per forzare un salto incondizionato a una
posizione predefinita, calcolata da un'espressione. La scelta è tra le posizioni
elencate, e dipende dal valore dell'espressione al momento in cui viene 
calcolata.
 
Per funzionare correttamente, l'espressione deve avere un valore compreso 
tra 1 e il numero di destinazioni. Se l'espressione ha un valore di 0 o
maggiore della destinazione più alta possibile, non sarà eseguito alcun salto.
 
@syntax ON expression GOTO label1[, label2[, ... ] ]
 
@example ON level GOTO level1, level2, level3
@usedInExample control_by_expression_02.bas
 
@target all
</usermanual> */
void on_goto( Environment * _environment, char * _expression ) {
 
    MAKE_LABEL
 
    Variable * expression = variable_retrieve( _environment, _expression );
 
    Conditional * conditional = malloc( sizeof( Conditional ) );
    conditional->label = strdup( label );
    conditional->type = CT_ON_GOTO;
    conditional->expression = variable_cast( _environment, expression->name, expression->type );
    conditional->expression->locked = 1;
    conditional->index = 1;
    conditional->next = _environment->conditionals;
    _environment->conditionals = conditional;
 
}

void on_goto_index( Environment * _environment, char * _label ) {
 
    Conditional * conditional = _environment->conditionals;
 
    if ( ! conditional ) {
        CRITICAL_INTERNAL_ERROR("on_goto_index called out of order (1)");
    }
 
    if ( conditional->type != CT_ON_GOTO ) {
        CRITICAL_INTERNAL_ERROR("on_goto_index called out of order (2)");
    }
 
    char realLabel[MAX_TEMPORARY_STORAGE];
    if (strcmp(_label, "q" ) == 0 && _environment->vestigialConfig.rchack_ostra_1172 ) {
        sprintf( realLabel, "lbl%s", _label );
    } else {
        strcpy( realLabel, _label );
    }
    label_referred_define_named( _environment, realLabel );
 
    Variable * index = variable_resident( _environment, VT_BYTE, "(index)");
 
    variable_store( _environment, index->name, conditional->index );
 
    Variable * expression = variable_retrieve( _environment, conditional->expression->name );
 
    cpu_bvneq( _environment, variable_compare( _environment, expression->name, index->name )->realName, realLabel );
 
    ++conditional->index;
 
};

void on_goto_number( Environment * _environment, int _number ) {
 
    label_referred_define_numeric( _environment, _number );
 
    char label[MAX_TEMPORARY_STORAGE]; sprintf( label, "_linenumber%d", _number );
 
    on_goto_index( _environment, label );
 
};

void on_goto_end( Environment * _environment ) {
 
    Conditional * conditional = _environment->conditionals;
 
    if ( ! conditional ) {
        CRITICAL_INTERNAL_ERROR("on_goto_end called out of order (1)");
    }
 
    if ( conditional->type != CT_ON_GOTO ) {
        CRITICAL_INTERNAL_ERROR("on_goto_end called out of order (2)");
    }
 
    _environment->conditionals->expression->locked = 0;
 
    _environment->conditionals = _environment->conditionals->next;
 
};