view test/torturethread.c @ 2752:edd2839b36f7

http://sources.redhat.com/ml/newlib/2002/msg00230.html Stephen L Moshier wrote: > > pow(x,y) returns 0 when x is very close to -1.0 and y is very large. > The following test program prints > > pow(1.0000000000000002e+00 4.5035996273704970e+15) = 2.7182818284590455e+00 > pow(-1.0000000000000002e+00 4.5035996273704970e+15) =0.0000000000000000e+00 > pow(9.9999999999999978e-01 4.5035996273704970e+15) = 3.6787944117144222e-01 > pow(-9.9999999999999978e-01 4.5035996273704970e+15) = 0.0000000000000000e+00 > > which is incorrect for the negative arguments raised to an odd integer > power. > > ----- > double pow (double, double); > > int > main () > { > double x, y, z; > > x = 1.0 + pow (2.0, -52.0); > y = 1.0 + pow (2.0, 52.0); > z = pow (x, y); > printf ("pow(%.16e %.16e) = %.16e\n", x, y, z); > x = -x; > z = pow (x, y); > printf ("pow(%.16e %.16e) = %.16e\n", x, y, z); > x = 1.0 - pow (2.0, -52.0); > z = pow (x, y); > printf ("pow(%.16e %.16e) = %.16e\n", x, y, z); > x = -x; > z = pow (x, y); > printf ("pow(%.16e %.16e) = %.16e\n", x, y, z); > } > ----- > > Here is a patch for newlib/libm/math/epow.c: Patch checked in and duplicated for ef_pow.c. Thanks. -- Jeff J.
author Sam Lantinga <slouken@libsdl.org>
date Mon, 15 Sep 2008 04:31:30 +0000
parents c121d94672cb
children
line wrap: on
line source


/* Simple test of the SDL threading code */

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <string.h>

#include "SDL.h"
#include "SDL_thread.h"

#define NUMTHREADS 10

static char volatile time_for_threads_to_die[NUMTHREADS];

/* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */
static void
quit(int rc)
{
    SDL_Quit();
    exit(rc);
}

int SDLCALL
SubThreadFunc(void *data)
{
    while (!*(int volatile *) data) {
        ;                       /*SDL_Delay(10); *//* do nothing */
    }
    return 0;
}

int SDLCALL
ThreadFunc(void *data)
{
    SDL_Thread *sub_threads[NUMTHREADS];
    int flags[NUMTHREADS];
    int i;
    int tid = (int) (uintptr_t) data;

    fprintf(stderr, "Creating Thread %d\n", tid);

    for (i = 0; i < NUMTHREADS; i++) {
        flags[i] = 0;
        sub_threads[i] = SDL_CreateThread(SubThreadFunc, &flags[i]);
    }

    printf("Thread '%d' waiting for signal\n", tid);
    while (time_for_threads_to_die[tid] != 1) {
        ;                       /* do nothing */
    }

    printf("Thread '%d' sending signals to subthreads\n", tid);
    for (i = 0; i < NUMTHREADS; i++) {
        flags[i] = 1;
        SDL_WaitThread(sub_threads[i], NULL);
    }

    printf("Thread '%d' exiting!\n", tid);

    return 0;
}

int
main(int argc, char *argv[])
{
    SDL_Thread *threads[NUMTHREADS];
    int i;

    /* Load the SDL library */
    if (SDL_Init(0) < 0) {
        fprintf(stderr, "Couldn't initialize SDL: %s\n", SDL_GetError());
        return (1);
    }

    signal(SIGSEGV, SIG_DFL);
    for (i = 0; i < NUMTHREADS; i++) {
        time_for_threads_to_die[i] = 0;
        threads[i] = SDL_CreateThread(ThreadFunc, (void *) (uintptr_t) i);

        if (threads[i] == NULL) {
            fprintf(stderr, "Couldn't create thread: %s\n", SDL_GetError());
            quit(1);
        }
    }

    for (i = 0; i < NUMTHREADS; i++) {
        time_for_threads_to_die[i] = 1;
    }

    for (i = 0; i < NUMTHREADS; i++) {
        SDL_WaitThread(threads[i], NULL);
    }
    SDL_Quit();
    return (0);
}