tmk_core/tool/mbed/mbed-sdk/libraries/fs/fat/MemFileSystem.h

   1 /* mbed Microcontroller Library - MemFileSystem
   2  * Copyright (c) 2008, sford
   3  */
   4
   5
   6 #ifndef MBED_MEMFILESYSTEM_H
   7 #define MBED_MEMFILESYSTEM_H
   8
   9 #include "FATFileSystem.h"
  10
  11 namespace mbed
  12 {
  13
  14     class MemFileSystem : public FATFileSystem
  15     {
  16     public:
  17
  18         // 2000 sectors, each 512 bytes (malloced as required)
  19         char *sectors[2000];
  20
  21         MemFileSystem(const char* name) : FATFileSystem(name) {
  22             memset(sectors, 0, sizeof(sectors));
  23         }
  24
  25         virtual ~MemFileSystem() {
  26             for(int i = 0; i < 2000; i++) {
  27                 if(sectors[i]) {
  28                     free(sectors[i]);
  29                 }
  30             }
  31         }
  32
  33         // read a sector in to the buffer, return 0 if ok
  34         virtual int disk_read(char *buffer, int sector) {
  35             if(sectors[sector] == 0) {
  36                 // nothing allocated means sector is empty
  37                 memset(buffer, 0, 512);
  38             } else {
  39                 memcpy(buffer, sectors[sector], 512);
  40             }
  41             return 0;
  42         }
  43
  44         // write a sector from the buffer, return 0 if ok
  45         virtual int disk_write(const char *buffer, int sector) {
  46             // if buffer is zero deallocate sector
  47             char zero[512];
  48             memset(zero, 0, 512);
  49             if(memcmp(zero, buffer, 512)==0) {
  50                 if(sectors[sector] != 0) {
  51                     free(sectors[sector]);
  52                     sectors[sector] = 0;
  53                 }
  54                 return 0;
  55             }
  56             // else allocate a sector if needed, and write
  57             if(sectors[sector] == 0) {
  58                 char *sec = (char*)malloc(512);
  59                 if(sec==0) {
  60                     return 1; // out of memory
  61                 }
  62                 sectors[sector] = sec;
  63             }
  64             memcpy(sectors[sector], buffer, 512);
  65             return 0;
  66         }
  67
  68         // return the number of sectors
  69         virtual int disk_sectors() {
  70             return sizeof(sectors)/sizeof(sectors[0]);
  71         }
  72
  73     };
  74
  75 }
  76
  77 #endif