wait_until.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 
 ****************************************************************************/

/* <usermanual>
@keyword WAIT UNTIL
 
@english
 
The ''WAIT UNTIL'' command allows you to suspend the execution of a thread until 
the indicated condition becomes ''TRUE''. In other words, the expression is 
evaluated and, if ''FALSE'', the execution will be suspended to send another 
scheduled thread to execute. If it becomes ''TRUE'', the execution of this thread
will continue.
 
@italian
 
Il comando ''WAIT UNTIL'' permette di sospendere l'esecuzione di un thread fino a
che la condizione indicata non diventa vera. In altri termini, l'espressione 
viene valutata e, se ''FALSE'', l'esecuzione sarà sospesa per mandare in esecuzione
un altro thread di quelli schedulati.  Se invece diventa TRUE, l'esecuzione di
questo thread proseguirà.
 
@syntax WAIT UNTIL expression
 
@example WAIT UNTIL x < 0
 
@target all
</usermanual> */
void wait_until( Environment * _environment ) {
 
    yield( _environment );
 
}
 
void wait_until_condition( Environment * _environment, char * _condition ) {
 
    _environment->anyProtothread = 1;
 
    if ( _environment->protothreadForbid ) {
        CRITICAL_MULTITASKING_FORBIDDEN();
    }
 
    if ( ! _environment->procedureName ) {
        CRITICAL_WAIT_UNTIL_CANNOT_BE_CALLED_OUTSIDE_PROCEDURE();
    }
 
    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_bvneq( _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;
    
}