Mercurial > sdl-ios-xcode

view src/stdlib/SDL_stdlib.c @ 4105:84882a89ca50 SDL-1.2

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Date: Thu, 27 Dec 2007 07:38:25 +0000 From: John Bartholomew Subject: [SDL] SDL Semaphore implementation broken on Windows? Hi, Over the past couple of days, I've been battling with SDL, SDL_Mixer and SMPEG to try to find an audio hang bug. I believe I've found the problem, which I think is a race condition inside SDL's semaphore implementation (at least the Windows implementation). The semaphore code uses Windows' built in semaphore functions, but it also maintains a separate count value. This count value is updated with bare increment and decrement operations in SemPost and SemWaitTimeout - no locking primitives to protect them. In tracking down the apparent audio bug, I found that at some point a semaphore's count value was being decremented to -1, which is clearly not a valid value for it to take. I'm still not certain exactly what sequence of operations is occuring for this to happen, but I believe that overall it's a race condition between a thread calling SemPost (which increments the count) and the thread on the other end calling SemWait (which decrements it). I will try to make a test case to verify this, but I'm not sure if I'll be able to (threading errors being difficult to reproduce even in the best circumstances). However, assuming this is the cause of my problems, there is a very simple fix: Windows provides InterlockedIncrement() and InterlockedDecrement() functions to perform increments and decrements which are guaranteed to be atomic. So the fix is in thread/win32/SDL_syssem.c: replace occurrences of --sem->count with InterlockedDecrement(&sem->count); and replace occurrences of ++sem->count with InterlockedIncrement(&sem->count); This is using SDL v1.2.12, built with VC++ 2008 Express, running on a Core 2 duo processor.
author Sam Lantinga <slouken@libsdl.org>
date Fri, 28 Dec 2007 22:05:17 +0000
parents bb6839704ed6
children 782fd950bd46 c121d94672cb a1b03ba2fcd0
line wrap: on
line source

/*
    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"

/* This file contains portable stdlib functions for SDL */

#include "SDL_stdinc.h"

#ifndef HAVE_LIBC
/* These are some C runtime intrinsics that need to be defined */

#if defined(_MSC_VER)

#ifndef __FLTUSED__
#define __FLTUSED__
#ifdef __cplusplus
   extern "C"
#endif
	   __declspec(selectany) int _fltused=1;
#endif

/* Float to long */
void __declspec(naked) _ftol()
{
	__asm {
		push        ebp
		mov         ebp,esp
		sub         esp,20h
		and         esp,0FFFFFFF0h
		fld         st(0)
		fst         dword ptr [esp+18h]
		fistp       qword ptr [esp+10h]
		fild        qword ptr [esp+10h]
		mov         edx,dword ptr [esp+18h]
		mov         eax,dword ptr [esp+10h]
		test        eax,eax
		je          integer_QnaN_or_zero
arg_is_not_integer_QnaN:
		fsubp       st(1),st
		test        edx,edx
		jns         positive
		fstp        dword ptr [esp]
		mov         ecx,dword ptr [esp]
		xor         ecx,80000000h
		add         ecx,7FFFFFFFh
		adc         eax,0
		mov         edx,dword ptr [esp+14h]
		adc         edx,0
		jmp         localexit
positive:
		fstp        dword ptr [esp]
		mov         ecx,dword ptr [esp]
		add         ecx,7FFFFFFFh
		sbb         eax,0
		mov         edx,dword ptr [esp+14h]
		sbb         edx,0
		jmp         localexit
integer_QnaN_or_zero:
		mov         edx,dword ptr [esp+14h]
		test        edx,7FFFFFFFh
		jne         arg_is_not_integer_QnaN
		fstp        dword ptr [esp+18h]
		fstp        dword ptr [esp+18h]
localexit:
		leave
		ret
	}
}
void __declspec(naked) _ftol2_sse()
{
	_ftol();
}

/* 64-bit math operators for 32-bit systems */
void __declspec(naked) _allmul()
{
	__asm {
		push        ebp
		mov         ebp,esp
		push        edi
		push        esi
		push        ebx
		sub         esp,0Ch
		mov         eax,dword ptr [ebp+10h]
		mov         edi,dword ptr [ebp+8]
		mov         ebx,eax
		mov         esi,eax
		sar         esi,1Fh
		mov         eax,dword ptr [ebp+8]
		mul         ebx
		imul        edi,esi
		mov         ecx,edx
		mov         dword ptr [ebp-18h],eax
		mov         edx,dword ptr [ebp+0Ch]
		add         ecx,edi
		imul        ebx,edx
		mov         eax,dword ptr [ebp-18h]
		lea         ebx,[ebx+ecx]
		mov         dword ptr [ebp-14h],ebx
		mov         edx,dword ptr [ebp-14h]
		add         esp,0Ch
		pop         ebx
		pop         esi
		pop         edi
		pop         ebp
		ret
	}
}
void __declspec(naked) _alldiv()
{
	__asm {
		push        edi
		push        esi
		push        ebx
		xor         edi,edi
		mov         eax,dword ptr [esp+14h]
		or          eax,eax
		jge         L1
		inc         edi
		mov         edx,dword ptr [esp+10h]
		neg         eax
		neg         edx
		sbb         eax,0
		mov         dword ptr [esp+14h],eax
		mov         dword ptr [esp+10h],edx
L1:
		mov         eax,dword ptr [esp+1Ch]
		or          eax,eax
		jge         L2
		inc         edi
		mov         edx,dword ptr [esp+18h]
		neg         eax
		neg         edx
		sbb         eax,0
		mov         dword ptr [esp+1Ch],eax
		mov         dword ptr [esp+18h],edx
L2:
		or          eax,eax
		jne         L3
		mov         ecx,dword ptr [esp+18h]
		mov         eax,dword ptr [esp+14h]
		xor         edx,edx
		div         ecx
		mov         ebx,eax
		mov         eax,dword ptr [esp+10h]
		div         ecx
		mov         edx,ebx
		jmp         L4
L3:
		mov         ebx,eax
		mov         ecx,dword ptr [esp+18h]
		mov         edx,dword ptr [esp+14h]
		mov         eax,dword ptr [esp+10h]
L5:
		shr         ebx,1
		rcr         ecx,1
		shr         edx,1
		rcr         eax,1
		or          ebx,ebx
		jne         L5
		div         ecx
		mov         esi,eax
		mul         dword ptr [esp+1Ch]
		mov         ecx,eax
		mov         eax,dword ptr [esp+18h]
		mul         esi
		add         edx,ecx
		jb          L6
		cmp         edx,dword ptr [esp+14h]
		ja          L6
		jb          L7
		cmp         eax,dword ptr [esp+10h]
		jbe         L7
L6:
		dec         esi
L7:
		xor         edx,edx
		mov         eax,esi
L4:
		dec         edi
		jne         L8
		neg         edx
		neg         eax
		sbb         edx,0
L8:
		pop         ebx
		pop         esi
		pop         edi
		ret         10h
	}
}
void __declspec(naked) _aulldiv()
{
	__asm {
		push        ebx
		push        esi
		mov         eax,dword ptr [esp+18h]
		or          eax,eax
		jne         L1
		mov         ecx,dword ptr [esp+14h]
		mov         eax,dword ptr [esp+10h]
		xor         edx,edx
		div         ecx
		mov         ebx,eax
		mov         eax,dword ptr [esp+0Ch]
		div         ecx
		mov         edx,ebx
		jmp         L2
L1:
		mov         ecx,eax
		mov         ebx,dword ptr [esp+14h]
		mov         edx,dword ptr [esp+10h]
		mov         eax,dword ptr [esp+0Ch]
L3:
		shr         ecx,1
		rcr         ebx,1
		shr         edx,1
		rcr         eax,1
		or          ecx,ecx
		jne         L3
		div         ebx
		mov         esi,eax
		mul         dword ptr [esp+18h]
		mov         ecx,eax
		mov         eax,dword ptr [esp+14h]
		mul         esi
		add         edx,ecx
		jb          L4
		cmp         edx,dword ptr [esp+10h]
		ja          L4
		jb          L5
		cmp         eax,dword ptr [esp+0Ch]
		jbe         L5
L4:
		dec         esi
L5:
		xor         edx,edx
		mov         eax,esi
L2:
		pop         esi
		pop         ebx
		ret         10h
	}
}
void __declspec(naked) _allrem()
{
	__asm {
		push        ebx
		push        edi
		xor         edi,edi
		mov         eax,dword ptr [esp+10h]
		or          eax,eax
		jge         L1
		inc         edi
		mov         edx,dword ptr [esp+0Ch]
		neg         eax
		neg         edx
		sbb         eax,0
		mov         dword ptr [esp+10h],eax
		mov         dword ptr [esp+0Ch],edx
L1:
		mov         eax,dword ptr [esp+18h]
		or          eax,eax
		jge         L2
		mov         edx,dword ptr [esp+14h]
		neg         eax
		neg         edx
		sbb         eax,0
		mov         dword ptr [esp+18h],eax
		mov         dword ptr [esp+14h],edx
L2:
		or          eax,eax
		jne         L3
		mov         ecx,dword ptr [esp+14h]
		mov         eax,dword ptr [esp+10h]
		xor         edx,edx
		div         ecx
		mov         eax,dword ptr [esp+0Ch]
		div         ecx
		mov         eax,edx
		xor         edx,edx
		dec         edi
		jns         L4
		jmp         L8
L3:
		mov         ebx,eax
		mov         ecx,dword ptr [esp+14h]
		mov         edx,dword ptr [esp+10h]
		mov         eax,dword ptr [esp+0Ch]
L5:
		shr         ebx,1
		rcr         ecx,1
		shr         edx,1
		rcr         eax,1
		or          ebx,ebx
		jne         L5
		div         ecx
		mov         ecx,eax
		mul         dword ptr [esp+18h]
		xchg        eax,ecx
		mul         dword ptr [esp+14h]
		add         edx,ecx
		jb          L6
		cmp         edx,dword ptr [esp+10h]
		ja          L6
		jb          L7
		cmp         eax,dword ptr [esp+0Ch]
		jbe         L7
L6:
		sub         eax,dword ptr [esp+14h]
		sbb         edx,dword ptr [esp+18h]
L7:
		sub         eax,dword ptr [esp+0Ch]
		sbb         edx,dword ptr [esp+10h]
		dec         edi
		jns         L8
L4:
		neg         edx
		neg         eax
		sbb         edx,0
L8:
		pop         edi
		pop         ebx
		ret         10h
	}
}
void __declspec(naked) _aullrem()
{
	__asm {
		push        ebx
		mov         eax,dword ptr [esp+14h]
		or          eax,eax
		jne         L1
		mov         ecx,dword ptr [esp+10h]
		mov         eax,dword ptr [esp+0Ch]
		xor         edx,edx
		div         ecx
		mov         eax,dword ptr [esp+8]
		div         ecx
		mov         eax,edx
		xor         edx,edx
		jmp         L2
L1:
		mov         ecx,eax
		mov         ebx,dword ptr [esp+10h]
		mov         edx,dword ptr [esp+0Ch]
		mov         eax,dword ptr [esp+8]
L3:
		shr         ecx,1
		rcr         ebx,1
		shr         edx,1
		rcr         eax,1
		or          ecx,ecx
		jne         L3
		div         ebx
		mov         ecx,eax
		mul         dword ptr [esp+14h]
		xchg        eax,ecx
		mul         dword ptr [esp+10h]
		add         edx,ecx
		jb          L4
		cmp         edx,dword ptr [esp+0Ch]
		ja          L4
		jb          L5
		cmp         eax,dword ptr [esp+8]
		jbe         L5
L4:
		sub         eax,dword ptr [esp+10h]
		sbb         edx,dword ptr [esp+14h]
L5:
		sub         eax,dword ptr [esp+8]
		sbb         edx,dword ptr [esp+0Ch]
		neg         edx
		neg         eax
		sbb         edx,0
L2:
		pop         ebx
		ret         10h
	}
}
void __declspec(naked) _alldvrm()
{
	__asm {
		push        edi
		push        esi
		push        ebp
		xor         edi,edi
		xor         ebp,ebp
		mov         eax,dword ptr [esp+14h]
		or          eax,eax
		jge         L1
		inc         edi
		inc         ebp
		mov         edx,dword ptr [esp+10h]
		neg         eax
		neg         edx
		sbb         eax,0
		mov         dword ptr [esp+14h],eax
		mov         dword ptr [esp+10h],edx
L1:
		mov         eax,dword ptr [esp+1Ch]
		or          eax,eax
		jge         L2
		inc         edi
		mov         edx,dword ptr [esp+18h]
		neg         eax
		neg         edx
		sbb         eax,0
		mov         dword ptr [esp+1Ch],eax
		mov         dword ptr [esp+18h],edx
L2:
		or          eax,eax
		jne         L3
		mov         ecx,dword ptr [esp+18h]
		mov         eax,dword ptr [esp+14h]
		xor         edx,edx
		div         ecx
		mov         ebx,eax
		mov         eax,dword ptr [esp+10h]
		div         ecx
		mov         esi,eax
		mov         eax,ebx
		mul         dword ptr [esp+18h]
		mov         ecx,eax
		mov         eax,esi
		mul         dword ptr [esp+18h]
		add         edx,ecx
		jmp         L4
L3:
		mov         ebx,eax
		mov         ecx,dword ptr [esp+18h]
		mov         edx,dword ptr [esp+14h]
		mov         eax,dword ptr [esp+10h]
L5:
		shr         ebx,1
		rcr         ecx,1
		shr         edx,1
		rcr         eax,1
		or          ebx,ebx
		jne         L5
		div         ecx
		mov         esi,eax
		mul         dword ptr [esp+1Ch]
		mov         ecx,eax
		mov         eax,dword ptr [esp+18h]
		mul         esi
		add         edx,ecx
		jb          L6
		cmp         edx,dword ptr [esp+14h]
		ja          L6
		jb          L7
		cmp         eax,dword ptr [esp+10h]
		jbe         L7
L6:
		dec         esi
		sub         eax,dword ptr [esp+18h]
		sbb         edx,dword ptr [esp+1Ch]
L7:
		xor         ebx,ebx
L4:
		sub         eax,dword ptr [esp+10h]
		sbb         edx,dword ptr [esp+14h]
		dec         ebp
		jns         L9
		neg         edx
		neg         eax
		sbb         edx,0
L9:
		mov         ecx,edx
		mov         edx,ebx
		mov         ebx,ecx
		mov         ecx,eax
		mov         eax,esi
		dec         edi
		jne         L8
		neg         edx
		neg         eax
		sbb         edx,0
L8:
		pop         ebp
		pop         esi
		pop         edi
		ret         10h
	}
}
void __declspec(naked) _aulldvrm()
{
	__asm {
		push        esi
		mov         eax,dword ptr [esp+14h]
		or          eax,eax
		jne         L1
		mov         ecx,dword ptr [esp+10h]
		mov         eax,dword ptr [esp+0Ch]
		xor         edx,edx
		div         ecx
		mov         ebx,eax
		mov         eax,dword ptr [esp+8]
		div         ecx
		mov         esi,eax
		mov         eax,ebx
		mul         dword ptr [esp+10h]
		mov         ecx,eax
		mov         eax,esi
		mul         dword ptr [esp+10h]
		add         edx,ecx
		jmp         L2
L1:
		mov         ecx,eax
		mov         ebx,dword ptr [esp+10h]
		mov         edx,dword ptr [esp+0Ch]
		mov         eax,dword ptr [esp+8]
L3:
		shr         ecx,1
		rcr         ebx,1
		shr         edx,1
		rcr         eax,1
		or          ecx,ecx
		jne         L3
		div         ebx
		mov         esi,eax
		mul         dword ptr [esp+14h]
		mov         ecx,eax
		mov         eax,dword ptr [esp+10h]
		mul         esi
		add         edx,ecx
		jb          L4
		cmp         edx,dword ptr [esp+0Ch]
		ja          L4
		jb          L5
		cmp         eax,dword ptr [esp+8]
		jbe         L5
L4:
		dec         esi
		sub         eax,dword ptr [esp+10h]
		sbb         edx,dword ptr [esp+14h]
L5:
		xor         ebx,ebx
L2:
		sub         eax,dword ptr [esp+8]
		sbb         edx,dword ptr [esp+0Ch]
		neg         edx
		neg         eax
		sbb         edx,0
		mov         ecx,edx
		mov         edx,ebx
		mov         ebx,ecx
		mov         ecx,eax
		mov         eax,esi
		pop         esi
		ret         10h
	}
}
void __declspec(naked) _allshl()
{
	__asm {
		cmp         cl,40h
		jae         RETZERO
		cmp         cl,20h
		jae         MORE32
		shld        edx,eax,cl
		shl         eax,cl
		ret
MORE32:
		mov         edx,eax
		xor         eax,eax
		and         cl,1Fh
		shl         edx,cl
		ret
RETZERO:
		xor         eax,eax
		xor         edx,edx
		ret
	}
}
void __declspec(naked) _aullshr()
{
	__asm {
		cmp         cl,40h
		jae         RETZERO
		cmp         cl,20h
		jae         MORE32
		shrd        eax,edx,cl
		shr         edx,cl
		ret
MORE32:
		mov         eax,edx
		xor         edx,edx
		and         cl,1Fh
		shr         eax,cl
		ret
RETZERO:
		xor         eax,eax
		xor         edx,edx
		ret
	}
}

#endif /* MSC_VER */

#endif /* !HAVE_LIBC */