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2288 | clevermous | 1 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; |
2 | ;; ;; |
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3 | ;; Copyright (C) KolibriOS team 2011. All rights reserved. ;; |
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4 | ;; Distributed under terms of the GNU General Public License ;; |
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5 | ;; ;; |
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6 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; |
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7 | |||
8 | $Revision: 2381 $ |
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9 | |||
10 | ; Simple implementation of timers. All timers are organized in a double-linked |
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11 | ; list, and the OS loop after every timer tick processes the list. |
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12 | |||
13 | ; This structure describes a timer for the kernel. |
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2381 | hidnplayr | 14 | struct TIMER |
15 | Next dd ? |
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16 | Prev dd ? |
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2288 | clevermous | 17 | ; These fields organize a double-linked list of all timers. |
2381 | hidnplayr | 18 | TimerFunc dd ? |
2288 | clevermous | 19 | ; Function to be called when the timer is activated. |
2381 | hidnplayr | 20 | UserData dd ? |
2288 | clevermous | 21 | ; The value that is passed as is to .TimerFunc. |
2381 | hidnplayr | 22 | Time dd ? |
2288 | clevermous | 23 | ; Time at which the timer should be activated. |
2381 | hidnplayr | 24 | Interval dd ? |
2288 | clevermous | 25 | ; Interval between activations of the timer, in 0.01s. |
26 | ends |
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27 | |||
28 | iglobal |
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29 | align 4 |
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30 | ; The head of timer list. |
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31 | timer_list: |
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32 | dd timer_list |
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33 | dd timer_list |
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34 | endg |
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35 | uglobal |
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36 | ; These two variables are used to synchronize access to the global list. |
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37 | ; Logically, they form an recursive mutex. Physically, the first variable holds |
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38 | ; the slot number of the current owner or 0, the second variable holds the |
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39 | ; recursion count. |
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40 | ; The mutex should be recursive to allow a timer function to add/delete other |
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41 | ; timers or itself. |
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42 | timer_list_owner dd 0 |
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43 | timer_list_numlocks dd 0 |
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44 | ; A timer function can delete any timer, including itself and the next timer in |
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45 | ; the chain. To handle such situation correctly, we keep the next timer in a |
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46 | ; global variable, so the removing operation can update it. |
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47 | timer_next dd 0 |
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48 | endg |
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49 | |||
50 | ; This internal function acquires the lock for the global list. |
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51 | lock_timer_list: |
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52 | mov edx, [CURRENT_TASK] |
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53 | @@: |
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54 | xor eax, eax |
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55 | lock cmpxchg [timer_list_owner], edx |
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56 | jz @f |
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57 | cmp eax, edx |
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58 | jz @f |
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59 | call change_task |
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60 | jmp @b |
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61 | @@: |
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62 | inc [timer_list_numlocks] |
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63 | ret |
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64 | |||
65 | ; This internal function releases the lock for the global list. |
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66 | unlock_timer_list: |
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67 | dec [timer_list_numlocks] |
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68 | jnz .nothing |
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69 | mov [timer_list_owner], 0 |
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70 | .nothing: |
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71 | ret |
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72 | |||
73 | ; This function adds a timer. |
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74 | ; If deltaStart is nonzero, the timer is activated after deltaStart hundredths |
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75 | ; of seconds starting from the current time. If interval is nonzero, the timer |
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76 | ; is activated every deltaWork hundredths of seconds starting from the first |
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77 | ; activation. The activated timer calls timerFunc as stdcall function with one |
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78 | ; argument userData. |
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79 | ; Return value is NULL if something has failed or some value which is opaque |
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80 | ; for the caller. Later this value can be used for cancel_timer_hs. |
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81 | proc timer_hs stdcall uses ebx, deltaStart:dword, interval:dword, \ |
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82 | timerFunc:dword, userData:dword |
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83 | ; 1. Allocate memory for the TIMER structure. |
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84 | ; 1a. Call the allocator. |
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85 | push sizeof.TIMER |
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86 | pop eax |
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87 | call malloc |
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88 | ; 1b. If allocation failed, return (go to 5) with eax = 0. |
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89 | test eax, eax |
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90 | jz .nothing |
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91 | ; 2. Setup the TIMER structure. |
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92 | xchg ebx, eax |
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93 | ; 2a. Copy values from the arguments. |
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94 | mov ecx, [interval] |
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95 | mov [ebx+TIMER.Interval], ecx |
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96 | mov ecx, [timerFunc] |
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97 | mov [ebx+TIMER.TimerFunc], ecx |
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98 | mov ecx, [userData] |
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99 | mov [ebx+TIMER.UserData], ecx |
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100 | ; 2b. Get time of the next activation. |
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101 | mov ecx, [deltaStart] |
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102 | test ecx, ecx |
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103 | jnz @f |
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104 | mov ecx, [interval] |
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105 | @@: |
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106 | add ecx, [timer_ticks] |
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107 | mov [ebx+TIMER.Time], ecx |
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108 | ; 3. Insert the TIMER structure to the global list. |
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109 | ; 3a. Acquire the lock. |
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110 | call lock_timer_list |
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111 | ; 3b. Insert an item at ebx to the tail of the timer_list. |
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112 | mov eax, timer_list |
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113 | mov ecx, [eax+TIMER.Prev] |
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114 | mov [ebx+TIMER.Next], eax |
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115 | mov [ebx+TIMER.Prev], ecx |
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116 | mov [eax+TIMER.Prev], ebx |
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117 | mov [ecx+TIMER.Next], ebx |
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118 | ; 3c. Release the lock. |
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119 | call unlock_timer_list |
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120 | ; 4. Return with eax = pointer to TIMER structure. |
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121 | xchg ebx, eax |
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122 | .nothing: |
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123 | ; 5. Returning. |
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124 | ret |
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125 | endp |
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126 | |||
127 | ; This function removes a timer. |
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128 | ; The only argument is [esp+4] = the value which was returned from timer_hs. |
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129 | cancel_timer_hs: |
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130 | push ebx ; save used register to be stdcall |
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131 | ; 1. Remove the TIMER structure from the global list. |
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132 | ; 1a. Acquire the lock. |
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133 | call lock_timer_list |
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134 | mov ebx, [esp+4+4] |
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135 | ; 1b. Delete an item at ebx from the double-linked list. |
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136 | mov eax, [ebx+TIMER.Next] |
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137 | mov ecx, [ebx+TIMER.Prev] |
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138 | mov [eax+TIMER.Prev], ecx |
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139 | mov [ecx+TIMER.Next], eax |
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140 | ; 1c. If we are removing the next timer in currently processing chain, |
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141 | ; the next timer for this timer becomes new next timer. |
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142 | cmp ebx, [timer_next] |
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143 | jnz @f |
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144 | mov [timer_next], eax |
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145 | @@: |
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146 | ; 1d. Release the lock. |
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147 | call unlock_timer_list |
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148 | ; 2. Free the TIMER structure. |
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149 | xchg eax, ebx |
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150 | call free |
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151 | ; 3. Return. |
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152 | pop ebx ; restore used register to be stdcall |
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153 | ret 4 ; purge one dword argument to be stdcall |
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154 | |||
155 | ; This function is regularly called from osloop. It processes the global list |
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156 | ; and activates the corresponding timers. |
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157 | check_timers: |
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158 | ; 1. Acquire the lock. |
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159 | call lock_timer_list |
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160 | ; 2. Loop over all registered timers, checking time. |
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161 | ; 2a. Get the first item. |
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162 | mov eax, [timer_list+TIMER.Next] |
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163 | mov [timer_next], eax |
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164 | .loop: |
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165 | ; 2b. Check for end of list. |
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166 | cmp eax, timer_list |
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167 | jz .done |
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168 | ; 2c. Get and store the next timer. |
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169 | mov edx, [eax+TIMER.Next] |
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170 | mov [timer_next], edx |
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171 | ; 2d. Check time for timer activation. |
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172 | ; We can't just compare [timer_ticks] and [TIMER.Time], since overflows are |
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173 | ; possible: if the current time is 0FFFFFFFFh ticks and timer should be |
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174 | ; activated in 3 ticks, the simple comparison will produce incorrect result. |
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175 | ; So we calculate the difference [timer_ticks] - [TIMER.Time]; if it is |
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176 | ; non-negative, the time is over; if it is negative, then either the time is |
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177 | ; not over or we have not processed this timer for 2^31 ticks, what is very |
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178 | ; unlikely. |
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179 | mov edx, [timer_ticks] |
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180 | sub edx, [eax+TIMER.Time] |
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181 | js .next |
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182 | ; The timer should be activated now. |
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183 | ; 2e. Store the timer data in the stack. This is required since 2f can delete |
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184 | ; the timer, invalidating the content. |
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185 | push [eax+TIMER.UserData] ; parameter for TimerFunc |
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186 | push [eax+TIMER.TimerFunc] ; to be restored in 2g |
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187 | ; 2f. Calculate time of next activation or delete the timer if it is one-shot. |
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188 | mov ecx, [eax+TIMER.Interval] |
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189 | add [eax+TIMER.Time], ecx |
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190 | test ecx, ecx |
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191 | jnz .nodelete |
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192 | stdcall cancel_timer_hs, eax |
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193 | .nodelete: |
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194 | ; 2g. Activate timer, using data from the stack. |
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195 | pop eax |
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196 | call eax |
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197 | .next: |
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198 | ; 2h. Advance to the next timer and continue the loop. |
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199 | mov eax, [timer_next] |
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200 | jmp .loop |
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201 | .done: |
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202 | ; 3. Release the lock. |
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203 | call unlock_timer_list |
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204 | ; 4. Return. |
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205 | ret |