wait_while.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
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 * http://www.apache.org/licenses/LICENSE-2.0
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/****************************************************************************
 * INCLUDE SECTION 
 ****************************************************************************/
 
#include "../../ugbc.h"
 
/****************************************************************************
 * CODE SECTION 
 ****************************************************************************/

/* <usermanual>
@keyword WAIT WHILE
 
@english
 
The ''WAIT WHILE'' command allows you to suspend the execution of a thread until 
the indicated condition becomes ''FALSE''. In other words, the expression is 
evaluated and, if ''TRUE'', the execution will be suspended to send another 
scheduled thread to execute. If it becomes ''FALSE'', the execution of this thread
will continue.
 
@italian
 
Il comando ''WAIT WHILE'' permette di sospendere l'esecuzione di un thread fino a
che la condizione indicata non diventa falsa. In altri termini, l'espressione 
viene valutata e, se ''TRUE'', l'esecuzione sarà sospesa per mandare in esecuzione
un altro thread di quelli schedulati.  Se invece diventa ''FALSE'', l'esecuzione di
questo thread proseguirà.
 
@syntax WAIT WHILE expression
 
@example WAIT WHILE NOT done
 
@target all
</usermanual> */
void wait_while( Environment * _environment ) {
 
    if ( _environment->emptyProcedure ) {
        return;
    }
 
    yield( _environment );
    
}
 
void wait_while_condition( Environment * _environment, char * _condition ) {
 
    if ( _environment->emptyProcedure ) {
        return;
    }
 
    if ( _environment->protothreadForbid ) {
        CRITICAL_MULTITASKING_FORBIDDEN();
    }
 
    if ( ! _environment->procedureName ) {
        CRITICAL_WAIT_WHILE_CANNOT_BE_CALLED_OUTSIDE_PROCEDURE();
    }
 
    _environment->anyProtothread = 1;
 
    MAKE_LABEL
 
    char protothreadLabel[MAX_TEMPORARY_STORAGE]; sprintf(protothreadLabel, "%spt%d", _environment->procedureName, _environment->protothreadStep );
 
    Variable * expression = variable_retrieve_or_define( _environment, _condition, VT_BYTE, 0 );
 
    cpu_bveq( _environment, expression->realName, protothreadLabel );
 
    cpu_protothread_save( _environment, "PROTOTHREADCT", ( _environment->protothreadStep - 1 ) );
    cpu_protothread_set_state( _environment, "PROTOTHREADCT", PROTOTHREAD_STATUS_WAITING );
    cpu_return( _environment );
    cpu_label( _environment, protothreadLabel );
    cpu_protothread_set_state( _environment, "PROTOTHREADCT", PROTOTHREAD_STATUS_RUNNING );
 
    ++_environment->protothreadStep;
    
}