filesys_8c-source.html

MP3播放器源代码, VS1003B

00161   ConsoleWrite(<span class="stringliteral">"Writing clusterchain from: "</span>); ConsolePutUInt(currentCluster);
00162   ConsoleWrite(<span class="stringliteral">"Fragment size (sectors): "</span>); ConsolePutUInt(fragSize);
00163   ConsoleWrite(<span class="stringliteral">"FatPageSector: "</span>); ConsolePutUInt(fatPageSector);
00164   ConsoleWrite(<span class="stringliteral">"EntryNumber: "</span>); ConsolePutUInt(entryNumber);
00165 
00166   
00167   <span class="comment">// WRITE CLUSTER CHAIN TO FIRST FAT</span>
00168 
00169   <span class="keywordflow">while</span> (fragSize&gt;<a class="code" href="filesys_8c.html#a5">fatSectorsPerCluster</a>){ 
00170     <span class="comment">// while more than 1 cluster left...</span>
00171 
00172     <span class="comment">// is the FAT clusterchain page changed?</span>
00173     <span class="keywordflow">if</span> (<a class="code" href="buffer_8c.html#a2">sectorAddress</a>.<a class="code" href="unionAddress.html#o0">l</a> != fatPageSector){
00174       <span class="comment">// Yes, have we advanced by 1 sector?</span>
00175       <span class="keywordflow">if</span> (<a class="code" href="buffer_8c.html#a2">sectorAddress</a>.<a class="code" href="unionAddress.html#o0">l</a> == (fatPageSector - 1)){
00176         <span class="comment">//Yes, we must save the edited sector</span>
00177         <a class="code" href="storage_8h.html#a4">WriteDiskSector</a> (<a class="code" href="buffer_8c.html#a2">sectorAddress</a>.<a class="code" href="unionAddress.html#o0">l</a>);
00179       }
00180       <span class="comment">// at least we need to load the new clusterchain page</span>
00181       <a class="code" href="buffer_8c.html#a2">sectorAddress</a>.<a class="code" href="unionAddress.html#o0">l</a> = fatPageSector;
00182       <a class="code" href="storage_8h.html#a2">ReadDiskSector</a>(<a class="code" href="buffer_8c.html#a2">sectorAddress</a>.<a class="code" href="unionAddress.html#o0">l</a>);
00183     }<span class="comment">//Load/Save FAT sector</span>
00184 
00185     
00186     <span class="comment">// Register Middle Entry</span>
00187    currentCluster++; <span class="comment">//advancce to next cluster</span>
00188     
00189     <span class="comment">//fragSize-=fatSectorsPerCluster; //we will register one cluster</span>
00190     <span class="comment">//to avoid memory spill in C compiler, the preceding line is written as:</span>
00191     <span class="keywordflow">for</span> (<a class="code" href="board_8c.html#a0">temp</a>.<a class="code" href="unionTemp.html#o0">c</a> = <a class="code" href="filesys_8c.html#a5">fatSectorsPerCluster</a>;<a class="code" href="board_8c.html#a0">temp</a>.<a class="code" href="unionTemp.html#o0">c</a>;<a class="code" href="board_8c.html#a0">temp</a>.<a class="code" href="unionTemp.html#o0">c</a>--){
00192       fragSize--;
00193     }
00194    
00195     <span class="keywordflow">if</span> (<a class="code" href="filesys_8h.html#a0">IS_FAT_32</a>){
00196       <a class="code" href="buffer_8c.html#a0">diskSect</a>.<a class="code" href="unionDiskBlock.html#o4">Fat32Table</a>[entryNumber]=currentCluster;
00197     }<span class="keywordflow">else</span>{
00198       <a class="code" href="buffer_8c.html#a0">diskSect</a>.<a class="code" href="unionDiskBlock.html#o3">Fat16Table</a>[entryNumber]=(currentCluster&amp;0xffff);
00199     }      
00200 
00201     <span class="comment">// Calculate next entry position in FAT records</span>
00202     fatPageSector = currentCluster;
00203     <span class="keywordflow">if</span> (!<a class="code" href="filesys_8h.html#a0">IS_FAT_32</a>){ <span class="comment">//FAT16</span>
00204       entryNumber = fatPageSector &amp; 0xff; 
00205       fatPageSector &gt;&gt;= 8; 
00206     }<span class="keywordflow">else</span>{ <span class="comment">//FAT32</span>
00207       entryNumber = fatPageSector &amp; 0x7f;
00208       fatPageSector &gt;&gt;= 7; 
00209     }
00210     fatPageSector += <a class="code" href="filesys_8c.html#a2">fatStart</a>;
00211 
00212   }<span class="comment">//while</span>
00213 
00214 
00215   <span class="comment">// WRITE THE FINAL ENTRY TO FAT CLUSTERCHAIN</span>
00216 
00217   <span class="comment">// is the FAT clusterchain page changed?</span>
00218   <span class="keywordflow">if</span> (<a class="code" href="buffer_8c.html#a2">sectorAddress</a>.<a class="code" href="unionAddress.html#o0">l</a> != fatPageSector){
00219     <span class="comment">// Yes, have we advanced by 1 sector?</span>
00220     <span class="keywordflow">if</span> (<a class="code" href="buffer_8c.html#a2">sectorAddress</a>.<a class="code" href="unionAddress.html#o0">l</a> == (fatPageSector - 1)){
00221       <span class="comment">//Yes, we must save the edited sector</span>
00222       <a class="code" href="storage_8h.html#a4">WriteDiskSector</a> (<a class="code" href="buffer_8c.html#a2">sectorAddress</a>.<a class="code" href="unionAddress.html#o0">l</a>);
00224         }
00225     <span class="comment">// at least we need to load the new clusterchain page</span>
00226     <a class="code" href="buffer_8c.html#a2">sectorAddress</a>.<a class="code" href="unionAddress.html#o0">l</a> = fatPageSector;
00227     <a class="code" href="storage_8h.html#a2">ReadDiskSector</a>(<a class="code" href="buffer_8c.html#a2">sectorAddress</a>.<a class="code" href="unionAddress.html#o0">l</a>);
00228   }<span class="comment">//Load/Save FAT sector</span>
00229   
00230 
00231   <span class="comment">//Write the Last entry</span>
00232   <span class="keywordflow">if</span> (<a class="code" href="filesys_8h.html#a0">IS_FAT_32</a>){
00233     <a class="code" href="buffer_8c.html#a0">diskSect</a>.<a class="code" href="unionDiskBlock.html#o4">Fat32Table</a>[entryNumber]=<a class="code" href="filesys_8c.html#a6">fragment</a>[1].<a class="code" href="structfragmentEntry.html#o0">start</a>;
00234   }<span class="keywordflow">else</span>{
00235     <a class="code" href="buffer_8c.html#a0">diskSect</a>.<a class="code" href="unionDiskBlock.html#o3">Fat16Table</a>[entryNumber]=(<a class="code" href="filesys_8c.html#a6">fragment</a>[1].<a class="code" href="structfragmentEntry.html#o0">start</a> &amp; 0xffff);
00236   }    
00237   <a class="code" href="storage_8h.html#a4">WriteDiskSector</a>(<a class="code" href="buffer_8c.html#a2">sectorAddress</a>.<a class="code" href="unionAddress.html#o0">l</a>); <span class="comment">//Write last sector</span>
00238     
00239   <a class="code" href="filesys_8h.html#a8">OpenFile</a>(0); <span class="comment">//Register FAT entry</span>
00240 
00241 }
00242 
00243 
00244 
00245 
<a name="l00248"></a><a class="code" href="filesys_8h.html#a11">00248</a> <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> <a class="code" href="filesys_8c.html#a17">ScanForFreeSector</a>(){
00249 
00250   <span class="comment">//ConsoleWrite("\rLooking for free space starting from ");</span>
00251 
00252   <span class="keywordflow">if</span> ((<a class="code" href="filesys_8c.html#a10">freeSector</a>) &amp;&amp; (<a class="code" href="filesys_8c.html#a10">freeSector</a>-<a class="code" href="filesys_8c.html#a4">dataStart</a>+1)%<a class="code" href="filesys_8c.html#a5">fatSectorsPerCluster</a>){
00253     <span class="comment">//Still room in current cluster...</span>
00254     <a class="code" href="filesys_8c.html#a10">freeSector</a>++;
00255 
00256     <span class="comment">//ConsoleWrite("free at sector ");</span>
00257     <span class="comment">//ConsolePutUInt(freeSector);</span>
00258 
00259     <span class="keywordflow">return</span> 1;
00260   }  
00261   
00262   <span class="keywordflow">if</span> (<a class="code" href="filesys_8c.html#a10">freeSector</a>){
00263     <span class="comment">//Advance to next sector</span>
00264     <a class="code" href="filesys_8c.html#a10">freeSector</a>++;
00265     <span class="comment">//switch from using sectors to using clusters</span>
00266     <a class="code" href="filesys_8c.html#a13">PConvertSectorToCluster</a>(&amp;<a class="code" href="filesys_8c.html#a10">freeSector</a>);
00267   }<span class="keywordflow">else</span>{
00268     <a class="code" href="filesys_8c.html#a10">freeSector</a>=3; <span class="comment">//starting cluster entry (should be 2?)</span>
00269   }
00270 
00271 
00272   <span class="comment">//scan until free entry is found</span>
00273   <span class="comment">//freeSector actually counts clusters here.</span>
00274   <span class="keywordflow">while</span>(<a class="code" href="filesys_8c.html#a15">GetFatEntry</a>(<a class="code" href="filesys_8c.html#a10">freeSector</a>)){    
00275     <a class="code" href="filesys_8c.html#a10">freeSector</a>++;
00276   }
00277 
00278   ConsoleWrite(<span class="stringliteral">"F"</span>);
00279   ConsolePutUInt(<a class="code" href="filesys_8c.html#a10">freeSector</a>);
00280 
00281   
00282   <span class="comment">//while (!KEY_BUTTON);</span>
00283   <span class="comment">//ConsoleWrite("free at cluster ");</span>
00284   <span class="comment">//ConsolePutUInt(freeSector);</span>
00285 
00286   <span class="comment">//switch back from using clusters to using sectors.</span>
00287   <a class="code" href="filesys_8c.html#a14">PConvertClusterToSector</a>(&amp;<a class="code" href="filesys_8c.html#a10">freeSector</a>);
00288 
00289   <span class="comment">//ConsoleWrite("sector ");</span>
00290   <span class="comment">//ConsolePutUInt(freeSector);</span>
00291 
00292   <span class="keywordflow">return</span> 1;
00293 }
00294 
00295