src/jthread/win32/jsemaphore.cpp

   1 /*
   2 Minetest
   3 Copyright (C) 2013 sapier, < sapier AT gmx DOT net >
   4
   5 This program is free software; you can redistribute it and/or modify
   6 it under the terms of the GNU Lesser General Public License as published by
   7 the Free Software Foundation; either version 2.1 of the License, or
   8 (at your option) any later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU Lesser General Public License for more details.
  14
  15 You should have received a copy of the GNU Lesser General Public License along
  16 with this program; if not, write to the Free Software Foundation, Inc.,
  17 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18 */
  19 #include "jthread/jsemaphore.h"
  20
  21 JSemaphore::JSemaphore() {
  22         m_hSemaphore = CreateSemaphore(
  23                         0,
  24                         0,
  25                         MAX_SEMAPHORE_COUNT,
  26                         0);
  27 }
  28
  29 JSemaphore::~JSemaphore() {
  30         CloseHandle(m_hSemaphore);
  31 }
  32
  33 JSemaphore::JSemaphore(int initval) {
  34         m_hSemaphore = CreateSemaphore(
  35                         0,
  36                         initval,
  37                         MAX_SEMAPHORE_COUNT,
  38                         0);
  39 }
  40
  41 void JSemaphore::Post() {
  42         ReleaseSemaphore(
  43                         m_hSemaphore,
  44                         1,
  45                         0);
  46 }
  47
  48 void JSemaphore::Wait() {
  49         WaitForSingleObject(
  50                         m_hSemaphore,
  51                         INFINITE);
  52 }
  53
  54 bool JSemaphore::Wait(unsigned int time_ms) {
  55         unsigned int retval = WaitForSingleObject(
  56                         m_hSemaphore,
  57                         time_ms);
  58
  59         if (retval == WAIT_OBJECT_0)
  60         {
  61                 return true;
  62         }
  63         else {
  64                 assert(retval == WAIT_TIMEOUT);
  65                 return false;
  66         }
  67 }
  68
  69 typedef LONG (NTAPI *_NtQuerySemaphore)(
  70     HANDLE SemaphoreHandle,
  71     DWORD SemaphoreInformationClass,
  72     PVOID SemaphoreInformation,
  73     ULONG SemaphoreInformationLength,
  74     PULONG ReturnLength OPTIONAL
  75 );
  76
  77 typedef struct _SEMAPHORE_BASIC_INFORMATION {
  78     ULONG CurrentCount;
  79     ULONG MaximumCount;
  80 } SEMAPHORE_BASIC_INFORMATION;
  81
  82 /* Note: this will only work as long as jthread is directly linked to application */
  83 /* it's gonna fail if someone tries to build jthread as dll */
  84 static _NtQuerySemaphore NtQuerySemaphore =
  85                 (_NtQuerySemaphore)
  86                 GetProcAddress
  87                 (GetModuleHandle ("ntdll.dll"), "NtQuerySemaphore");
  88
  89 int JSemaphore::GetValue() {
  90         SEMAPHORE_BASIC_INFORMATION BasicInfo;
  91         LONG retval;
  92
  93         assert(NtQuerySemaphore);
  94
  95         retval = NtQuerySemaphore (m_hSemaphore, 0,
  96                 &BasicInfo, sizeof (SEMAPHORE_BASIC_INFORMATION), NULL);
  97
  98         if (retval == ERROR_SUCCESS)
  99         {
 100                 return BasicInfo.CurrentCount;
 101         }
 102         else {
 103                 assert("unable to read semaphore count" == 0);
 104         }
 105 }
 106