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#include "vmc.h" |
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// Fat table functions |
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unsigned int getFatEntry ( int fd, unsigned int cluster, unsigned int* indir_fat_clusters, GetFat_Mode Mode ) |
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{ |
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int unit = ( fd == g_Vmc_Image[ 0 ].fd ) ? 0 : 1; |
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// The fat index, aka which cluster we want to know about |
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unsigned int fat_index = cluster; |
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// The offset in the fat cluster where we can find information about the sector |
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unsigned int fat_offset = fat_index % ( g_Vmc_Image[ unit ].cluster_size / 4 ); |
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// Which fat cluster that the information would be in |
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unsigned int indirect_index = fat_index / ( g_Vmc_Image[ unit ].cluster_size / 4 ); |
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// The offset in the indirect fat cluster that points to the fat table we are interested in |
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unsigned int indirect_offset = indirect_index % ( g_Vmc_Image[ unit ].cluster_size / 4 ); |
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// This gives the location of the fat_offset inside of the indirect fat cluster list. Each indirect fat cluster can point to |
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// 256 regular fat clusters, and each fat cluster holds information on 256 sectors. |
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unsigned int dbl_indirect_index = fat_index / ( ( g_Vmc_Image[ unit ].cluster_size / 4 ) * ( g_Vmc_Image[ unit ].cluster_size / 4 ) ); |
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// Cache indirect file table? ( Generally we will be accessing the first part of it for most virtual memory cards ) |
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// Get the data for the indirect fat cluster ( as indicated by dbl_indirect_index ) |
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unsigned int indirect_cluster_num = indir_fat_clusters[ dbl_indirect_index ]; |
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if ( g_Vmc_Image[ unit ].last_idc != indirect_cluster_num ) |
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readCluster ( fd, ( unsigned char* ) g_Vmc_Image[ unit ].indirect_cluster, indirect_cluster_num ); |
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g_Vmc_Image[ unit ].last_idc = indirect_cluster_num; |
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// Get the data from the fat cluster ( pointed to by the indirect fat cluster ) |
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unsigned int fat_cluster_num = g_Vmc_Image[ unit ].indirect_cluster[ indirect_offset ]; |
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if ( g_Vmc_Image[ unit ].last_cluster != fat_cluster_num ) |
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readCluster ( fd, ( unsigned char* ) g_Vmc_Image[ unit ].fat_cluster, fat_cluster_num ); |
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g_Vmc_Image[ unit ].last_cluster = fat_cluster_num; |
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// Check if the entry in the fat table corresponds to a free cluster or a eof cluster |
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if ( g_Vmc_Image[ unit ].fat_cluster[ fat_offset ] == FREE_CLUSTER || g_Vmc_Image[ unit ].fat_cluster[ fat_offset ] == EOF_CLUSTER ) |
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return g_Vmc_Image[ unit ].fat_cluster[ fat_offset ]; |
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if ( Mode == FAT_MASK ) |
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{ |
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if ( g_Vmc_Image[ unit ].fat_cluster[ fat_offset ] & MASK_CLUSTER ) |
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{ |
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return MASK_CLUSTER; |
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} |
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else |
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{ |
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return 0; |
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} |
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} |
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// Return the fat entry, but remove the most significant bit. |
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return g_Vmc_Image[ unit ].fat_cluster[ fat_offset ] & FREE_CLUSTER; |
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} |
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unsigned int setFatEntry ( int fd, unsigned int cluster, unsigned int value, unsigned int* indir_fat_clusters, SetFat_Mode Mode ) |
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{ |
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int unit = ( fd == g_Vmc_Image[ 0 ].fd ) ? 0 : 1; |
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// The fat index, aka which cluster we want to know about |
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unsigned int fat_index = cluster; |
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// The offset in the fat cluster where we can find information about the sector |
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unsigned int fat_offset = fat_index % ( g_Vmc_Image[ unit ].cluster_size / 4 ); |
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// Which fat cluster that the information would be in |
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unsigned int indirect_index = fat_index / ( g_Vmc_Image[ unit ].cluster_size / 4 ); |
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// The offset in the indirect fat cluster that points to the fat table we are interested in |
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unsigned int indirect_offset = indirect_index % ( g_Vmc_Image[ unit ].cluster_size / 4 ); |
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// This gives the location of the fat_offset inside of the indirect fat cluster list. Each indirect fat cluster can point to |
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// 256 regular fat clusters, and each fat cluster holds information on 256 sectors. |
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unsigned int dbl_indirect_index = fat_index / ( ( g_Vmc_Image[ unit ].cluster_size / 4 ) * ( g_Vmc_Image[ unit ].cluster_size / 4 ) ); |
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// Cache indirect file table? ( Generally we will be accessing the first part of it for most virtual memory cards |
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// Get the data for the indirect fat cluster ( as indicated by dbl_indirect_index ) |
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unsigned int indirect_cluster_num = indir_fat_clusters[ dbl_indirect_index ]; |
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if ( g_Vmc_Image[ unit ].last_idc != indirect_cluster_num ) |
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readCluster ( fd, ( unsigned char* ) g_Vmc_Image[ unit ].indirect_cluster, indirect_cluster_num ); |
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g_Vmc_Image[ unit ].last_idc = indirect_cluster_num; |
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// Get the data from the fat cluster ( pointed to by the indirect fat cluster ) |
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unsigned int fat_cluster_num = g_Vmc_Image[ unit ].indirect_cluster[ indirect_offset ]; |
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if ( g_Vmc_Image[ unit ].last_cluster != fat_cluster_num ) |
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readCluster ( fd, ( unsigned char* ) g_Vmc_Image[ unit ].fat_cluster, fat_cluster_num ); |
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g_Vmc_Image[ unit ].last_cluster = fat_cluster_num; |
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if ( value == FREE_CLUSTER || value == EOF_CLUSTER || Mode == FAT_RESET ) |
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{ |
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g_Vmc_Image[ unit ].fat_cluster[ fat_offset ] = value; |
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} |
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else |
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{ |
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g_Vmc_Image[ unit ].fat_cluster[ fat_offset ] = value | MASK_CLUSTER; |
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} |
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writeCluster ( fd, ( unsigned char* ) g_Vmc_Image[ unit ].fat_cluster, fat_cluster_num ); |
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// Update last free cluster |
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if ( ( value == FREE_CLUSTER && Mode == FAT_SET ) || ( Mode == FAT_RESET ) ) |
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{ |
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if ( cluster < g_Vmc_Image[ unit ].last_free_cluster ) |
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{ |
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g_Vmc_Image[ unit ].last_free_cluster = cluster; |
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} |
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} |
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return 0; |
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} |