Diff: SDCard.h

Revision:

5:d85e20b6b904

Parent:

4:9a5878d316d5

Child:

6:ddf09d859ed7

--- a/SDCard.h	Fri Aug 27 00:59:28 2010 +0000
+++ b/SDCard.h	Sat Jan 15 05:58:22 2011 +0000
@@ -19,7 +19,7 @@
         unsigned char CommandCRCTable[256];
             //CRC7 lookup table
         unsigned char DataCRCTable[512];
-            //CRC CCITT lookup table
+            //CRC16 CCITT lookup table
         unsigned char OCR[4];
             //operating conditions register
         unsigned char CSD[16];
@@ -32,31 +32,39 @@
             //low for low-capacity, high for high-capacity
         bool CRCMode;
             //low to disable CRCs, high to enable CRCs
-        unsigned char Workspace[5];
-            //all-purpose work area
         unsigned int Timeout;
             //timeout limit
         unsigned int t;
             //timeout counter
+        unsigned char Workspace[5];
+            //all-purpose work area
 
         unsigned char Initialize();
             //complete all initialization operations
-        void Command(unsigned char Index, unsigned int Argument, unsigned char* Response);
+        void Command(unsigned char Index,
+            unsigned int Argument, unsigned char* Response);
             //sends command to the SD card
-        void CommandCRC(unsigned char* IndexPtr, unsigned int* ArgumentPtr, unsigned char* Result);
-            //calculates the command CRC7 result with a lookup table
-        void DataCRC(unsigned short Length, unsigned char* Data, unsigned char* Result);
-            //calculates the CRC16 result of the input with a lookup table
-        void GenerateCRCTable(
-            unsigned char Size, unsigned long long Generator, unsigned char* Table);
-            //pre-calculates CRC results for efficient checking
+        void CommandCRC(unsigned char* IndexPtr,
+            unsigned int* ArgumentPtr, unsigned char* Result);
+            //calculates the SD card proprietary CRC7 result of an SD card
+            //command, records one-byte solution in Result
+        void DataCRC(unsigned short Length,
+            unsigned char* Data, unsigned char* Result);
+            //calculates the CRC16 result of the number of bytes in Data
+            //given by Length and stores the two-byte solution in Result,
+            //assumes DataCRCTable has already been calculated
+        void GenerateCRCTable(unsigned char Size,
+            unsigned long long Generator, unsigned char* Table);
+            //pre-calculates CRC results for efficient checking, assumes
+            //pre-allocated Table is large enough to hold the number of
+            //bytes given in Size
 
         virtual unsigned char disk_initialize();
         virtual unsigned char disk_status();
-        virtual unsigned char disk_read(
-            unsigned char* buff, unsigned long sector, unsigned char count);
-        virtual unsigned char disk_write(
-            const unsigned char* buff, unsigned long sector, unsigned char count);
+        virtual unsigned char disk_read(unsigned char* buff,
+            unsigned long sector, unsigned char count);
+        virtual unsigned char disk_write(const unsigned char* buff,
+            unsigned long sector, unsigned char count);
         virtual unsigned char disk_sync();
         virtual unsigned long disk_sector_count();
         virtual unsigned short disk_sector_size();
@@ -64,26 +72,35 @@
             //FAT system virtual function definitions, called by FAT module
 
     public:
-        SDCard(PinName mosi, PinName miso, PinName sck, PinName cs, const char* DiskName);
-            //constructor requires SPI and DigitalOut pins, and a directory name
+        SDCard(PinName mosi, PinName miso, PinName sck, PinName cs,
+            const char* DiskName);
+            //constructor requires SPI and DigitalOut pins, and a
+            //directory name
         virtual ~SDCard();
             //destructor deallocates tables and workspace
         unsigned char Log(unsigned char Control, unsigned char Data);
-            //multipurpose raw data-logging method with three modes of operation
+            //multipurpose raw data-logging method with three modes
             //Control   description
-            //  0       synchronizes card and resets internal counter to finalize I/O operations
-            //  1       successively write input to a raw data byte in order starting at address 0
-            //  2       successively read and return a raw data byte in order starting at address 0
+            //  0       synchronizes card and resets internal counter to
+            //              finalize I/O operations
+            //  1       successively write input to a raw data byte in
+            //              order starting at address 0
+            //  2       successively read and return a raw data byte in
+            //              order starting at address 0
             //return data from sync or write operations, and input
-            //data of sync or read operations are "don't care" bits
+            //data of sync or read operations are stuff bits
         unsigned char Write(unsigned int Address, unsigned char* Data);
-        unsigned char Write(unsigned int Address, unsigned char SectorCount, unsigned char* Data);
-            //write data sectors to the card
+            //write single 512B sector to card at Address from Data
+        unsigned char Write(unsigned int Address,
+            unsigned char SectorCount, unsigned char* Data);
+            //write SectorCount 512B sectors to card at Address from Data
         unsigned char Read(unsigned int Address, unsigned char* Data);
-        unsigned char Read(unsigned int Address, unsigned char SectorCount,  unsigned char* Data);
-            //read data sectors from the card
+            //read single 512B sector from card at Address into Data
+        unsigned char Read(unsigned int Address,
+            unsigned char SectorCount,  unsigned char* Data);
+            //read SectorCount 512B sectors from card at Address into Data
         unsigned char SelectCRCMode(bool Mode);
-            //turn CRC mode on or off, default is off
+            //toggle CRC mode; high for on or low for off, default is off
         void SetTimeout(unsigned int Retries);
             //change the number of retries for interface functions;
             //increase if lines are unreliable; default is 1024