[$BA0(B] $BL\ [$B]

Simple DirectMedia Layer API $B$r;H$&(B

$B%9%l%C%I(B

  • $BC1=c$J%9%l%C%I$N:n@.(B

$B%9%l%C%I$N@8@.$O(B SDL_CreateThread() $B$K4X?t$rEO$9$3$H$G$J$5$l$^$&!#(B $B4X?t$+$iLa$C$?$H$-!"[email protected]$7$F$$$l$P!"(B $B$"$J$?$N4X?t$O%"%W%j%1!<%7%g%s$NB>$NItJ,$HJB9T$7$F(B $B<+?H$N$NItJ,$G;H$o$l$?%a%b%j$d(B $B%U%!%$%k%O%s%I%k$K%"%/%;%9$9$k$3$H$,$G$-$^$9!#(B

 Tip:
SDL_CreateThread() $B$N(B 2 $BHVL\$N0z?t$O%9%l%C%I4X?t$K%Q%i%a!<%?$H$7$FEO$5$l$^$9!#(B $B%9%?%C%/>e$NCM$d%9%l%C%I$G;H$o$l$k%G!<%?$X$N%]%$%s%?$rEO$9$?$a$K(B $B;H$&$3$H$,$G$-$^$9!#(B
Example: 
#include "SDL_thread.h"

int global_data = 0;

int thread_func(void *unused)
{
    int last_value = 0;

    while ( global_data != -1 ) {
        if ( global_data != last_value ) {
            printf("Data value changed to %d\n", global_data);
            last_value = global_data;
        }
        SDL_Delay(100);
    }
    printf("Thread quitting\n");
    return(0);
}

{
    SDL_Thread *thread;
    int i;

    thread = SDL_CreateThread(thread_func, NULL);
    if ( thread == NULL ) {
        fprintf(stderr, "Unable to create thread: %s\n", SDL_GetError());
        return;
    }

    for ( i=0; i<5; ++i ) {
        printf("Changing value to %d\n", i);
        global_data = i;
        SDL_Delay(1000);
    }

    printf("Signaling thread to quit\n");
    global_data = -1;
    SDL_WaitThread(thread, NULL);
}
  • $B%j%=!<%9$X$NF14|%"%/%;%9(B

2 $B$D0J>e$N%9%l%C%I$+$i%j%=!<%9$X$N%"%/%;%9$r6X;_$9$k$3$H$,$G$-$^$9!#(B $B$=$l$K$O!"$^$:(B mutex $B$r:n@.$7!"%j%=!<%9$X$N%"%/%;%9$r(B $B%m%C%/(B(SDL_mutexP())$B$H%"%s%m%C%/(B(SDL_mutexV())$B$G0O$_$^$9!#(B

 Tip:
2 $B$D0J>e$N%9%l%C%I$+$i%"%/%;%9$5$l$&$k%G!<%?$O(B $BA4$F(B mutex $B$GJ]8n$5$l$kI,MW$,$"$j$^$9!#(B
Example: 
#include "SDL_thread.h"
#include "SDL_mutex.h"

int potty = 0;
int gotta_go;

int thread_func(void *data)
{
    SDL_mutex *lock = (SDL_mutex *)data;
    int times_went;

    times_went = 0;
    while ( gotta_go ) {
        SDL_mutexP(lock);    /* potty($B$*$^$k(B)$B$r%m%C%/(B */
        ++potty;
        printf("Thread %d using the potty\n", SDL_ThreadID());
        if ( potty > 1 ) {
            printf("Uh oh, somebody else is using the potty!\n");
        }
        --potty;
        SDL_mutexV(lock);
        ++times_went;
    }
    printf("Yep\n");
    return(times_went);
}

{
    const int progeny = 5;
    SDL_Thread *kids[progeny];
    SDL_mutex  *lock;
    int i, lots;

    /* $BF14|%m%C%/$r:n@.(B */
    lock = SDL_CreateMutex();

    gotta_go = 1;
    for ( i=0; i<progeny; ++i ) {
        kids[i] = SDL_CreateThread(thread_func, lock);
    }

    SDL_Delay(5*1000);
    SDL_mutexP(lock);
    printf("Everybody done?\n");
    gotta_go = 0;
    SDL_mutexV(lock);

    for ( i=0; i<progeny; ++i ) {
        SDL_WaitThread(kids[i], &lots);
        printf("Thread %d used the potty %d times\n", i+1, lots);
    }
    SDL_DestroyMutex(lock);
}

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