filesys_8c.html

MP3 Player Source Code

00869   <span class="comment">/* OK, let's calculate */</span>
00870   <span class="comment">/* First, let's get rid of the idea that we have byte addresses</span>
00871 <span class="comment">     in the file system. Nope, let's only deal in physical disk</span>
00872 <span class="comment">     sectors of 512 bytes. First we convert the FAT byter per sector</span>
00873 <span class="comment">     value to "512B disk sectors per fat sector" value. */</span>
00874 
00875   <a class="code" href="buffer_8c.html#a0">diskSect</a>.<a class="code" href="unionDiskBlock.html#o0">fat</a>.<a class="code" href="structDiskBlock_1_1Fat.html#o2">BPB_BytsPerSec</a> /= 512;
00876 
00877   <span class="comment">/* Then we adjust the Sector per Cluster to mean physical disk</span>
00878 <span class="comment">     sectors. in 99% of the cases it is already so because bytes</span>
00879 <span class="comment">     per sector almost always is 512 in FAT. Maximum cluster size</span>
00880 <span class="comment">     is 65536 bytes (128 disk sectors). */</span>
00881 
00882   <a class="code" href="filesys_8c.html#a5">fatSectorsPerCluster</a> =
00883     <a class="code" href="buffer_8c.html#a0">diskSect</a>.<a class="code" href="unionDiskBlock.html#o0">fat</a>.<a class="code" href="structDiskBlock_1_1Fat.html#o3">BPB_SecPerClus</a> *= <a class="code" href="buffer_8c.html#a0">diskSect</a>.<a class="code" href="unionDiskBlock.html#o0">fat</a>.<a class="code" href="structDiskBlock_1_1Fat.html#o2">BPB_BytsPerSec</a>;
00884   <span class="comment">/* Note: BPB_BytsPerSec has already been divided by 512 */</span>  
00885 
00886   ConsoleWrite(<span class="stringliteral">"\rSectors per Cluster: "</span>);
00887   ConsolePutUInt(fatSectorsPerCluster);
00888   
00889   <a class="code" href="filesys_8c.html#a2">fatStart</a> = (<span class="keywordtype">unsigned</span> <span class="keywordtype">long</span>)<a class="code" href="buffer_8c.html#a2">sectorAddress</a>.<a class="code" href="unionAddress.html#o0">l</a>
00890     + (<span class="keywordtype">unsigned</span> <span class="keywordtype">long</span>)<a class="code" href="buffer_8c.html#a0">diskSect</a>.<a class="code" href="unionDiskBlock.html#o0">fat</a>.<a class="code" href="structDiskBlock_1_1Fat.html#o4">BPB_RsvdSecCnt</a> 
00891     * (<span class="keywordtype">unsigned</span> <span class="keywordtype">long</span>)<a class="code" href="buffer_8c.html#a0">diskSect</a>.<a class="code" href="unionDiskBlock.html#o0">fat</a>.<a class="code" href="structDiskBlock_1_1Fat.html#o2">BPB_BytsPerSec</a>;
00892 
00893   ConsoleWrite(<span class="stringliteral">"\rFAT Start sector: "</span>);
00894   ConsolePutUInt(fatStart);
00895 
00896   <a class="code" href="filesys_8c.html#a3">rootStart</a> = <a class="code" href="buffer_8c.html#a0">diskSect</a>.<a class="code" href="unionDiskBlock.html#o0">fat</a>.<a class="code" href="structDiskBlock_1_1Fat.html#o9">BPB_FATSz16</a>;
00897   <span class="keywordflow">if</span> (<a class="code" href="filesys_8c.html#a3">rootStart</a>==0){
00898     <span class="keywordflow">if</span> (!<a class="code" href="filesys_8h.html#a0">IS_FAT_32</a>) 
00899       <span class="keywordflow">return</span> 0x0b; <span class="comment">/* should be FAT32; can not find root directory */</span>
00900     <a class="code" href="filesys_8c.html#a3">rootStart</a> = <a class="code" href="buffer_8c.html#a0">diskSect</a>.<a class="code" href="unionDiskBlock.html#o0">fat</a>.<a class="code" href="structDiskBlock_1_1Fat.html#o14">ext</a>.<a class="code" href="unionDiskBlock_1_1Fat_1_1Extensions.html#o1">_32</a>.<a class="code" href="structDiskBlock_1_1Fat_1_1Extensions_1_1Fat32Specific.html#o0">BPB_FATSz32</a>;
00901   }
00902   <a class="code" href="filesys_8c.html#a3">rootStart</a> *= <a class="code" href="buffer_8c.html#a0">diskSect</a>.<a class="code" href="unionDiskBlock.html#o0">fat</a>.<a class="code" href="structDiskBlock_1_1Fat.html#o5">BPB_NumFATs</a>;
00903   <a class="code" href="filesys_8c.html#a3">rootStart</a> *= <a class="code" href="buffer_8c.html#a0">diskSect</a>.<a class="code" href="unionDiskBlock.html#o0">fat</a>.<a class="code" href="structDiskBlock_1_1Fat.html#o2">BPB_BytsPerSec</a>; <span class="comment">/* ADJUSTED BytsPerSec! */</span>
00904   <a class="code" href="filesys_8c.html#a3">rootStart</a> += <a class="code" href="filesys_8c.html#a2">fatStart</a>;
00905 
00906   ConsoleWrite(<span class="stringliteral">"\rRoot start sector: "</span>);
00907   ConsolePutUInt(rootStart);
00908 
00909   <a class="code" href="filesys_8c.html#a4">dataStart</a> = <a class="code" href="buffer_8c.html#a0">diskSect</a>.<a class="code" href="unionDiskBlock.html#o0">fat</a>.<a class="code" href="structDiskBlock_1_1Fat.html#o6">BPB_RootEntCnt</a> &gt;&gt; 4;
00910   <a class="code" href="filesys_8c.html#a4">dataStart</a> += <a class="code" href="filesys_8c.html#a3">rootStart</a>;
00911   <a class="code" href="filesys_8c.html#a4">dataStart</a> -= (<a class="code" href="filesys_8c.html#a5">fatSectorsPerCluster</a>*2); <span class="comment">/*first cluster is cluster 2*/</span>
00912 
00913   ConsoleWrite(<span class="stringliteral">"\rData start sector: "</span>);
00914   ConsolePutUInt(dataStart);
00915   ConsolePutChar(13);
00916 
00917   <span class="keywordflow">return</span> 0;
00918 }
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<a class="anchor" name="a21" doxytag="filesys.c::FGetChar" ></a><p>
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          <td class="md" nowrap valign="top"> Public unsigned char FGetChar           </td>
          <td class="md" valign="top">(&nbsp;</td>
          <td class="mdname1" valign="top" nowrap>          </td>
          <td class="md" valign="top">&nbsp;)&nbsp;</td>
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<p>
Read a character from current file. 
<p>
This can be called after calling OpenFile. It is a slow method for reading character based file data. fileSize holds the number of characters still left in file to be read, check for fileSize=0 to detect end-of-file. If FGetChar is called after the end of file is reached, it does nothing and returns 0. 
<p>
Definition at line <a class="el" href="filesys_8c-source.html#l00561">561</a> of file <a class="el" href="filesys_8c-source.html">filesys.c</a>.
<p>
References <a class="el" href="buffer_8h-source.html#l00107">DiskBlock::Raw::buf</a>, <a class="el" href="buffer_8c-source.html#l00013">dataBufPtr</a>, <a class="el" href="buffer_8c-source.html#l00010">diskSect</a>, <a class="el" href="filesys_8c-source.html#l00047">fileSize</a>, <a class="el" href="buffer_8h-source.html#l00129">Address::l</a>, <a class="el" href="filesys_8c-source.html#l00541">LoadNextSector()</a>, <a class="el" href="board_8h-source.html#l00262">Public</a>, <a class="el" href="unionDiskBlock.html#o1">DiskBlock::raw</a>, <a class="el" href="storage_8c-source.html#l00110">ReadDiskSector()</a>, and <a class="el" href="buffer_8c-source.html#l00015">sectorAddress</a>.
<p>
Referenced by <a class="el" href="aviplay_8c-source.html#l00015">GetAVIBlock()</a>.
<p>
<pre class="fragment"><div>00561                                {
00562 
00563   <span class="keywordflow">if</span> (!<a class="code" href="filesys_8c.html#a7">fileSize</a>) <span class="keywordflow">return</span> 0; <span class="comment">//return 0 for end-of-file</span>
00564 
00565   <span class="keywordflow">if</span> (<a class="code" href="buffer_8c.html#a1">dataBufPtr</a>==0){
00566     <span class="comment">/* A file has been opened but not read from yet, so read the first</span>
00567 <span class="comment">       sector. */</span>
00568     <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>);
00569     <a class="code" href="buffer_8c.html#a1">dataBufPtr</a> = <a class="code" href="buffer_8c.html#a0">diskSect</a>.<a class="code" href="unionDiskBlock.html#o1">raw</a>.<a class="code" href="structDiskBlock_1_1Raw.html#o0">buf</a>;
00570   }
00571 
00572   <span class="keywordflow">if</span> (<a class="code" href="buffer_8c.html#a1">dataBufPtr</a>&gt;<a class="code" href="buffer_8c.html#a0">diskSect</a>.<a class="code" href="unionDiskBlock.html#o1">raw</a>.<a class="code" href="structDiskBlock_1_1Raw.html#o0">buf</a>+511){
00573     <span class="comment">/* An end of sector has been reached, read the next sector */</span>    
00574     <span class="keywordflow">if</span> (<a class="code" href="filesys_8c.html#a20">LoadNextSector</a>()){
00575       <span class="comment">/* Error, end-of-file according to FAT records */</span>
00576       <span class="keywordflow">return</span> 0; <span class="comment">/* must return something */</span>
00577     }
00578     <a class="code" href="buffer_8c.html#a1">dataBufPtr</a>=<a class="code" href="buffer_8c.html#a0">diskSect</a>.<a class="code" href="unionDiskBlock.html#o1">raw</a>.<a class="code" href="structDiskBlock_1_1Raw.html#o0">buf</a>;
00579   }
00580 
00581   <span class="comment">/* Everything should now be ok for reading a byte. */</span>
00582 
00583   <a class="code" href="filesys_8c.html#a7">fileSize</a>--;
00584   <span class="keywordflow">return</span> (*<a class="code" href="buffer_8c.html#a1">dataBufPtr</a>++);
00585 }
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Here is the call graph for this function:<p><center><img src="filesys_8c_a21_cgraph.png" border="0" usemap="#filesys_8c_a21_cgraph_map" alt=""></center>
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<a class="anchor" name="a15" doxytag="filesys.c::GetFatEntry" ></a><p>
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          <td class="md" nowrap valign="top"> unsigned long GetFatEntry           </td>
          <td class="md" valign="top">(&nbsp;</td>
          <td class="md" nowrap valign="top">unsigned long&nbsp;</td>
          <td class="mdname1" valign="top" nowrap> <em>clusterNumber</em>          </td>
          <td class="md" valign="top">&nbsp;)&nbsp;</td>
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<p>
Return the FAT entry for cluster clusterNumber. 
<p>

<p>
Definition at line <a class="el" href="filesys_8c-source.html#l00085">85</a> of file <a class="el" href="filesys_8c-source.html">filesys.c</a>.
<p>
References <a class="el" href="buffer_8c-source.html#l00010">diskSect</a>, <a class="el" href="buffer_8h-source.html#l00114">DiskBlock::Fat16Table</a>, <a class="el" href="buffer_8h-source.html#l00117">DiskBlock::Fat32Table</a>, <a class="el" href="filesys_8c-source.html#l00021">fatStart</a>, <a class="el" href="filesys_8h-source.html#l00015">IS_FAT_32</a>, <a class="el" href="buffer_8h-source.html#l00129">Address::l</a>, <a class="el" href="storage_8c-source.html#l00110">ReadDiskSector()</a>, and <a class="el" href="buffer_8c-source.html#l00015">sectorAddress</a>.
<p>