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4066 | shikhin | 1 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; |
2 | ;; ;; |
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3 | ;; Contains common resource allocation + freeing code. ;; |
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4 | ;; ;; |
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5363 | yogev_ezra | 5 | ;; Copyright (C) KolibriOS team 2013-2015. All rights reserved. ;; |
4891 | shikhin | 6 | ;; Distributed under terms of the GNU General Public License ;; |
4066 | shikhin | 7 | ;; ;; |
8 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; |
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9 | |||
4850 | mario79 | 10 | $Revision: 5363 $ |
11 | |||
12 | |||
4066 | shikhin | 13 | ;--------------------------------------------------------------------- |
14 | ; Frees a resource (block/inode). |
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15 | ; Input: eax = resource ID. |
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16 | ; edi = function pointer of ext2_bg_*_bitmap form, to |
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17 | ; get bitmap of resource. |
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18 | ; ecx = 0, block; 1, inode. |
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19 | ; ebp = pointer to EXTFS. |
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20 | ; Output: Block marked as free in block group. |
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21 | ; eax = error code. |
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22 | ;--------------------------------------------------------------------- |
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23 | ext2_resource_free: |
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24 | push ebx edx esi |
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25 | |||
26 | ; Get block group. |
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27 | sub eax, [ebp + EXTFS.superblock + EXT2_SB_STRUC.first_data_block] |
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28 | xor edx, edx |
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29 | div [ebp + EXTFS.superblock + EXT2_SB_STRUC.blocks_per_group] |
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30 | push eax edx |
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31 | |||
32 | call edi |
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33 | test eax, eax |
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34 | jz .fail |
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35 | mov esi, eax |
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36 | |||
37 | ; Read the bitmap. |
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38 | mov eax, ebx |
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39 | mov edx, eax |
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40 | mov ebx, [ebp + EXTFS.ext2_save_block] |
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41 | call ext2_block_read |
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42 | test eax, eax |
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43 | jnz .fail |
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44 | |||
45 | pop eax |
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46 | ; Mark bit free. |
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47 | call bitmap_clear_bit |
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48 | test eax, eax |
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49 | jz @F |
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50 | |||
51 | ; No need to save anything. |
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52 | xor eax, eax |
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53 | |||
54 | add esp, 4 |
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55 | jmp .return |
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56 | |||
57 | @@: |
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58 | mov eax, edx |
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59 | mov ebx, [ebp + EXTFS.ext2_save_block] |
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60 | call ext2_block_write |
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61 | test eax, eax |
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62 | jnz .fail |
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63 | |||
64 | ; Read the descriptor. |
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65 | mov eax, [esp] |
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66 | call ext2_bg_read_desc |
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67 | test eax, eax |
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68 | jz .fail_bg_desc_read |
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69 | |||
70 | lea eax, [eax + EXT2_BLOCK_GROUP_DESC.free_blocks_count] |
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71 | shl ecx, 1 |
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72 | add eax, ecx |
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73 | inc word[eax] |
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74 | |||
75 | lea eax, [ebp + EXTFS.superblock + EXT2_SB_STRUC.free_block_count] |
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76 | shl ecx, 1 |
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77 | add eax, ecx |
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78 | inc dword[eax] |
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79 | |||
80 | pop eax |
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81 | call ext2_bg_write_desc |
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82 | |||
83 | .return: |
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84 | pop esi edx ebx |
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85 | ret |
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86 | |||
87 | .fail: |
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88 | add esp, 4 |
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89 | .fail_bg_desc_read: |
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90 | add esp, 4 |
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91 | xor eax, eax |
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92 | not eax |
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93 | jmp .return |
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94 | |||
95 | ;--------------------------------------------------------------------- |
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96 | ; Allocates a resource. |
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97 | ; Input: eax = inode ID for "preference". |
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98 | ; ebp = pointer to EXTFS. |
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99 | ; [esp + 4], func pointer to ext2_bg_*_bitmap |
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100 | ; [esp + 8], pointer to free_*_count in SB. |
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101 | ; [esp + 12], *_per_group |
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102 | ; [esp + 16], offset to free_*_count in bg descriptor. |
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103 | ; [esp + 20], *_count |
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104 | ; Output: Resource marked as set in block group. |
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105 | ; eax = error code. |
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106 | ; ebx = resource ID. |
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107 | ;--------------------------------------------------------------------- |
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108 | ext2_resource_alloc: |
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109 | ; Block allocation is a pretty serious area, since bad allocation |
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110 | ; can lead to fragmentation. Thus, the best way to allocate that |
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111 | ; comes to mind is to allocate around an inode as much as possible. |
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112 | ; On the other hand, this isn't about a single inode/file/directory, |
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113 | ; and focusing just around the preferred inode would lead to |
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114 | ; congestion. Thus, after much thought, the chosen allocation algorithm |
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115 | ; is to search forward, then backward. |
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116 | push ecx edx esi edi |
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117 | |||
118 | cmp dword[esp + 16 + 8], 0 |
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119 | jnz @F |
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120 | |||
121 | ; No free blocks. |
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122 | xor eax, eax |
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123 | not eax |
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124 | pop edi esi edx ecx |
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125 | ret 20 |
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126 | |||
127 | @@: |
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128 | ; Calculate which block group the preferred inode belongs to. |
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129 | dec eax |
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130 | xor edx, edx |
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131 | |||
132 | ; EAX = block group. |
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133 | div [ebp + EXTFS.superblock + EXT2_SB_STRUC.inodes_per_group] |
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134 | push eax |
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135 | push eax |
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136 | |||
137 | mov edi, .forward |
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138 | |||
139 | .test_block_group: |
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140 | call dword[esp + 16 + 8 + 4] |
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141 | test eax, eax |
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142 | jz .fail |
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143 | mov esi, eax |
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144 | |||
145 | mov eax, ebx |
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146 | mov edx, eax |
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147 | mov ebx, [ebp + EXTFS.ext2_save_block] |
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148 | call ext2_block_read |
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149 | test eax, eax |
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150 | jnz .fail |
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151 | |||
152 | mov ecx, [esp + 16 + 8 + 12] |
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153 | call ext2_find_free_bit |
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154 | cmp eax, 0xFFFFFFFF |
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155 | jne @F |
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156 | |||
157 | mov eax, edi |
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158 | jmp eax |
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159 | |||
160 | @@: |
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161 | mov ecx, eax |
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162 | |||
163 | mov eax, edx |
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164 | mov ebx, [ebp + EXTFS.ext2_save_block] |
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165 | call ext2_block_write |
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166 | test eax, eax |
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167 | jnz .fail |
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168 | |||
169 | ; ecx: the index of the matched entry. |
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170 | ; [esp]: block group where we found. |
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171 | ; [esp + 4]: starting block group. |
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172 | ; esi: block group descriptor. |
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173 | mov eax, [esp] ; Index of block group in which we found. |
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174 | mul dword[esp + 16 + 8 + 12] |
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175 | add eax, ecx |
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176 | mov ebx, eax |
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177 | |||
178 | mov eax, [esp + 16 + 8 + 8] |
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179 | dec dword[eax] |
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180 | |||
181 | mov eax, esi |
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182 | add eax, [esp + 16 + 8 + 16] |
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183 | dec word[eax] |
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184 | |||
185 | pop eax |
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186 | call ext2_bg_write_desc |
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187 | |||
188 | add esp, 4 |
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189 | jmp .return |
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190 | |||
191 | ; Continue forward. |
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192 | .forward: |
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193 | inc dword[esp] |
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194 | mov eax, [esp] |
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195 | mul dword[esp + 16 + 8 + 12] |
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196 | cmp eax, [esp + 16 + 8 + 20] |
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197 | jbe @F |
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198 | |||
199 | ; We need to go backward. |
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200 | mov eax, [esp + 4] |
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201 | mov [esp], eax |
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202 | mov edi, .backward |
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203 | jmp .backward |
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204 | |||
205 | @@: |
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206 | mov eax, [esp] |
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207 | jmp .test_block_group |
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208 | |||
209 | ; Continue backward. |
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210 | .backward: |
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211 | cmp dword[esp], 0 |
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212 | je .fail |
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213 | |||
214 | dec dword[esp] |
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215 | mov eax, [esp] |
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216 | jmp .test_block_group |
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217 | |||
218 | .return: |
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219 | pop edi esi edx ecx |
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220 | ret 20 |
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221 | |||
222 | .fail: |
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223 | add esp, 8 |
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224 | xor eax, eax |
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225 | not eax |
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226 | jmp .return |