Mercurial > sdl-ios-xcode
view src/timer/dc/SDL_systimer.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 | 99210400e8b9 |
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/* SDL - Simple DirectMedia Layer Copyright (C) 1997-2006 Sam Lantinga This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA Sam Lantinga slouken@libsdl.org */ #include "SDL_config.h" #ifdef SDL_TIMER_DC #include <kos.h> #include "SDL_thread.h" #include "SDL_timer.h" #include "../SDL_timer_c.h" static unsigned start; /* jif = ms * HZ /1000 ms = jif * 1000/HZ */ void SDL_StartTicks(void) { /* Set first ticks value */ start = jiffies; } Uint32 SDL_GetTicks(void) { return ((jiffies - start) * 1000 / HZ); } void SDL_Delay(Uint32 ms) { thd_sleep(ms); } /* Data to handle a single periodic alarm */ static int timer_alive = 0; static SDL_Thread *timer = NULL; static int RunTimer(void *unused) { while (timer_alive) { if (SDL_timer_running) { SDL_ThreadedTimerCheck(); } SDL_Delay(10); } return (0); } /* This is only called if the event thread is not running */ int SDL_SYS_TimerInit(void) { timer_alive = 1; timer = SDL_CreateThread(RunTimer, NULL); if (timer == NULL) return (-1); return (SDL_SetTimerThreaded(1)); } void SDL_SYS_TimerQuit(void) { timer_alive = 0; if (timer) { SDL_WaitThread(timer, NULL); timer = NULL; } } int SDL_SYS_StartTimer(void) { SDL_SetError("Internal logic error: DC uses threaded timer"); return (-1); } void SDL_SYS_StopTimer(void) { return; } #endif /* SDL_TIMER_DC */ /* vi: set ts=4 sw=4 expandtab: */