David Styles
/
SDTicker
SDFileSystem.cpp@0:b545e012d041, 2009-11-25 (annotated)
- Committer:
- DaveStyles
- Date:
- Wed Nov 25 22:37:12 2009 +0000
- Revision:
- 0:b545e012d041
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
DaveStyles | 0:b545e012d041 | 1 | /* mbed Microcontroller Library - SDFileSystem |
DaveStyles | 0:b545e012d041 | 2 | * Copyright (c) 2008-2009, sford |
DaveStyles | 0:b545e012d041 | 3 | * |
DaveStyles | 0:b545e012d041 | 4 | * Introduction |
DaveStyles | 0:b545e012d041 | 5 | * ------------ |
DaveStyles | 0:b545e012d041 | 6 | * SD and MMC cards support a number of interfaces, but common to them all |
DaveStyles | 0:b545e012d041 | 7 | * is one based on SPI. This is the one I'm implmenting because it means |
DaveStyles | 0:b545e012d041 | 8 | * it is much more portable even though not so performant, and we already |
DaveStyles | 0:b545e012d041 | 9 | * have the mbed SPI Interface! |
DaveStyles | 0:b545e012d041 | 10 | * |
DaveStyles | 0:b545e012d041 | 11 | * The main reference I'm using is Chapter 7, "SPI Mode" of: |
DaveStyles | 0:b545e012d041 | 12 | * http://www.sdcard.org/developers/tech/sdcard/pls/Simplified_Physical_Layer_Spec.pdf |
DaveStyles | 0:b545e012d041 | 13 | * |
DaveStyles | 0:b545e012d041 | 14 | * SPI Startup |
DaveStyles | 0:b545e012d041 | 15 | * ----------- |
DaveStyles | 0:b545e012d041 | 16 | * The SD card powers up in SD mode. The SPI interface mode is selected by |
DaveStyles | 0:b545e012d041 | 17 | * asserting CS low and sending the reset command (CMD0). The card will |
DaveStyles | 0:b545e012d041 | 18 | * respond with a (R1) response. |
DaveStyles | 0:b545e012d041 | 19 | * |
DaveStyles | 0:b545e012d041 | 20 | * CMD8 is optionally sent to determine the voltage range supported, and |
DaveStyles | 0:b545e012d041 | 21 | * indirectly determine whether it is a version 1.x SD/non-SD card or |
DaveStyles | 0:b545e012d041 | 22 | * version 2.x. I'll just ignore this for now. |
DaveStyles | 0:b545e012d041 | 23 | * |
DaveStyles | 0:b545e012d041 | 24 | * ACMD41 is repeatedly issued to initialise the card, until "in idle" |
DaveStyles | 0:b545e012d041 | 25 | * (bit 0) of the R1 response goes to '0', indicating it is initialised. |
DaveStyles | 0:b545e012d041 | 26 | * |
DaveStyles | 0:b545e012d041 | 27 | * You should also indicate whether the host supports High Capicity cards, |
DaveStyles | 0:b545e012d041 | 28 | * and check whether the card is high capacity - i'll also ignore this |
DaveStyles | 0:b545e012d041 | 29 | * |
DaveStyles | 0:b545e012d041 | 30 | * SPI Protocol |
DaveStyles | 0:b545e012d041 | 31 | * ------------ |
DaveStyles | 0:b545e012d041 | 32 | * The SD SPI protocol is based on transactions made up of 8-bit words, with |
DaveStyles | 0:b545e012d041 | 33 | * the host starting every bus transaction by asserting the CS signal low. The |
DaveStyles | 0:b545e012d041 | 34 | * card always responds to commands, data blocks and errors. |
DaveStyles | 0:b545e012d041 | 35 | * |
DaveStyles | 0:b545e012d041 | 36 | * The protocol supports a CRC, but by default it is off (except for the |
DaveStyles | 0:b545e012d041 | 37 | * first reset CMD0, where the CRC can just be pre-calculated, and CMD8) |
DaveStyles | 0:b545e012d041 | 38 | * I'll leave the CRC off I think! |
DaveStyles | 0:b545e012d041 | 39 | * |
DaveStyles | 0:b545e012d041 | 40 | * Standard capacity cards have variable data block sizes, whereas High |
DaveStyles | 0:b545e012d041 | 41 | * Capacity cards fix the size of data block to 512 bytes. I'll therefore |
DaveStyles | 0:b545e012d041 | 42 | * just always use the Standard Capacity cards with a block size of 512 bytes. |
DaveStyles | 0:b545e012d041 | 43 | * This is set with CMD16. |
DaveStyles | 0:b545e012d041 | 44 | * |
DaveStyles | 0:b545e012d041 | 45 | * You can read and write single blocks (CMD17, CMD25) or multiple blocks |
DaveStyles | 0:b545e012d041 | 46 | * (CMD18, CMD25). For simplicity, I'll just use single block accesses. When |
DaveStyles | 0:b545e012d041 | 47 | * the card gets a read command, it responds with a response token, and then |
DaveStyles | 0:b545e012d041 | 48 | * a data token or an error. |
DaveStyles | 0:b545e012d041 | 49 | * |
DaveStyles | 0:b545e012d041 | 50 | * SPI Command Format |
DaveStyles | 0:b545e012d041 | 51 | * ------------------ |
DaveStyles | 0:b545e012d041 | 52 | * Commands are 6-bytes long, containing the command, 32-bit argument, and CRC. |
DaveStyles | 0:b545e012d041 | 53 | * |
DaveStyles | 0:b545e012d041 | 54 | * +---------------+------------+------------+-----------+----------+--------------+ |
DaveStyles | 0:b545e012d041 | 55 | * | 01 | cmd[5:0] | arg[31:24] | arg[23:16] | arg[15:8] | arg[7:0] | crc[6:0] | 1 | |
DaveStyles | 0:b545e012d041 | 56 | * +---------------+------------+------------+-----------+----------+--------------+ |
DaveStyles | 0:b545e012d041 | 57 | * |
DaveStyles | 0:b545e012d041 | 58 | * As I'm not using CRC, I can fix that byte to what is needed for CMD0 (0x95) |
DaveStyles | 0:b545e012d041 | 59 | * |
DaveStyles | 0:b545e012d041 | 60 | * All Application Specific commands shall be preceded with APP_CMD (CMD55). |
DaveStyles | 0:b545e012d041 | 61 | * |
DaveStyles | 0:b545e012d041 | 62 | * SPI Response Format |
DaveStyles | 0:b545e012d041 | 63 | * ------------------- |
DaveStyles | 0:b545e012d041 | 64 | * The main response format (R1) is a status byte (normally zero). Key flags: |
DaveStyles | 0:b545e012d041 | 65 | * idle - 1 if the card is in an idle state/initialising |
DaveStyles | 0:b545e012d041 | 66 | * cmd - 1 if an illegal command code was detected |
DaveStyles | 0:b545e012d041 | 67 | * |
DaveStyles | 0:b545e012d041 | 68 | * +-------------------------------------------------+ |
DaveStyles | 0:b545e012d041 | 69 | * R1 | 0 | arg | addr | seq | crc | cmd | erase | idle | |
DaveStyles | 0:b545e012d041 | 70 | * +-------------------------------------------------+ |
DaveStyles | 0:b545e012d041 | 71 | * |
DaveStyles | 0:b545e012d041 | 72 | * R1b is the same, except it is followed by a busy signal (zeros) until |
DaveStyles | 0:b545e012d041 | 73 | * the first non-zero byte when it is ready again. |
DaveStyles | 0:b545e012d041 | 74 | * |
DaveStyles | 0:b545e012d041 | 75 | * Data Response Token |
DaveStyles | 0:b545e012d041 | 76 | * ------------------- |
DaveStyles | 0:b545e012d041 | 77 | * Every data block written to the card is acknowledged by a byte |
DaveStyles | 0:b545e012d041 | 78 | * response token |
DaveStyles | 0:b545e012d041 | 79 | * |
DaveStyles | 0:b545e012d041 | 80 | * +----------------------+ |
DaveStyles | 0:b545e012d041 | 81 | * | xxx | 0 | status | 1 | |
DaveStyles | 0:b545e012d041 | 82 | * +----------------------+ |
DaveStyles | 0:b545e012d041 | 83 | * 010 - OK! |
DaveStyles | 0:b545e012d041 | 84 | * 101 - CRC Error |
DaveStyles | 0:b545e012d041 | 85 | * 110 - Write Error |
DaveStyles | 0:b545e012d041 | 86 | * |
DaveStyles | 0:b545e012d041 | 87 | * Single Block Read and Write |
DaveStyles | 0:b545e012d041 | 88 | * --------------------------- |
DaveStyles | 0:b545e012d041 | 89 | * |
DaveStyles | 0:b545e012d041 | 90 | * Block transfers have a byte header, followed by the data, followed |
DaveStyles | 0:b545e012d041 | 91 | * by a 16-bit CRC. In our case, the data will always be 512 bytes. |
DaveStyles | 0:b545e012d041 | 92 | * |
DaveStyles | 0:b545e012d041 | 93 | * +------+---------+---------+- - - -+---------+-----------+----------+ |
DaveStyles | 0:b545e012d041 | 94 | * | 0xFE | data[0] | data[1] | | data[n] | crc[15:8] | crc[7:0] | |
DaveStyles | 0:b545e012d041 | 95 | * +------+---------+---------+- - - -+---------+-----------+----------+ |
DaveStyles | 0:b545e012d041 | 96 | */ |
DaveStyles | 0:b545e012d041 | 97 | |
DaveStyles | 0:b545e012d041 | 98 | #include "SDFileSystem.h" |
DaveStyles | 0:b545e012d041 | 99 | |
DaveStyles | 0:b545e012d041 | 100 | #define SD_COMMAND_TIMEOUT 5000 |
DaveStyles | 0:b545e012d041 | 101 | |
DaveStyles | 0:b545e012d041 | 102 | SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name) : |
DaveStyles | 0:b545e012d041 | 103 | FATFileSystem(name), _spi(mosi, miso, sclk), _cs(cs) { |
DaveStyles | 0:b545e012d041 | 104 | _cs = 1; |
DaveStyles | 0:b545e012d041 | 105 | } |
DaveStyles | 0:b545e012d041 | 106 | |
DaveStyles | 0:b545e012d041 | 107 | int SDFileSystem::disk_initialize() { |
DaveStyles | 0:b545e012d041 | 108 | |
DaveStyles | 0:b545e012d041 | 109 | fprintf(stderr,"Initialising\n"); |
DaveStyles | 0:b545e012d041 | 110 | |
DaveStyles | 0:b545e012d041 | 111 | |
DaveStyles | 0:b545e012d041 | 112 | _spi.frequency(1000); // Set to 100kHz for initialisation |
DaveStyles | 0:b545e012d041 | 113 | |
DaveStyles | 0:b545e012d041 | 114 | // Initialise the card by clocking it a bit (cs = 1) |
DaveStyles | 0:b545e012d041 | 115 | for(int i=0; i<16; i++) { |
DaveStyles | 0:b545e012d041 | 116 | _spi.write(0xFF); |
DaveStyles | 0:b545e012d041 | 117 | } |
DaveStyles | 0:b545e012d041 | 118 | |
DaveStyles | 0:b545e012d041 | 119 | // send CMD0, should return with all zeros except IDLE STATE set (bit 0) |
DaveStyles | 0:b545e012d041 | 120 | if(_cmd(0, 0) != 0x01) { |
DaveStyles | 0:b545e012d041 | 121 | fprintf(stderr, "Not in idle state\n"); |
DaveStyles | 0:b545e012d041 | 122 | return 1; |
DaveStyles | 0:b545e012d041 | 123 | } |
DaveStyles | 0:b545e012d041 | 124 | |
DaveStyles | 0:b545e012d041 | 125 | // ACMD41 to give host capacity support (repeat until not busy) |
DaveStyles | 0:b545e012d041 | 126 | // ACMD41 is application specific command, so we send APP_CMD (CMD55) beforehand |
DaveStyles | 0:b545e012d041 | 127 | for(int i=0;; i++) { |
DaveStyles | 0:b545e012d041 | 128 | _cmd(55, 0); |
DaveStyles | 0:b545e012d041 | 129 | int response = _cmd(41, 0); |
DaveStyles | 0:b545e012d041 | 130 | if(response == 0) { |
DaveStyles | 0:b545e012d041 | 131 | break; |
DaveStyles | 0:b545e012d041 | 132 | } else if(i > SD_COMMAND_TIMEOUT) { |
DaveStyles | 0:b545e012d041 | 133 | fprintf(stderr, "Timeout waiting for card\n"); |
DaveStyles | 0:b545e012d041 | 134 | return 1; |
DaveStyles | 0:b545e012d041 | 135 | } |
DaveStyles | 0:b545e012d041 | 136 | } |
DaveStyles | 0:b545e012d041 | 137 | |
DaveStyles | 0:b545e012d041 | 138 | _sectors = _sd_sectors(); |
DaveStyles | 0:b545e012d041 | 139 | |
DaveStyles | 0:b545e012d041 | 140 | // Set block length to 512 (CMD16) |
DaveStyles | 0:b545e012d041 | 141 | if(_cmd(16, 512) != 0) { |
DaveStyles | 0:b545e012d041 | 142 | fprintf(stderr, "Set block timeout\n"); |
DaveStyles | 0:b545e012d041 | 143 | return 1; |
DaveStyles | 0:b545e012d041 | 144 | } |
DaveStyles | 0:b545e012d041 | 145 | |
DaveStyles | 0:b545e012d041 | 146 | _spi.frequency(1000000); // Set to 1MHz for data transfer |
DaveStyles | 0:b545e012d041 | 147 | return 0; |
DaveStyles | 0:b545e012d041 | 148 | } |
DaveStyles | 0:b545e012d041 | 149 | |
DaveStyles | 0:b545e012d041 | 150 | int SDFileSystem::disk_write(const char *buffer, int block_number) { |
DaveStyles | 0:b545e012d041 | 151 | // set write address for single block (CMD24) |
DaveStyles | 0:b545e012d041 | 152 | if(_cmd(24, block_number * 512) != 0) { |
DaveStyles | 0:b545e012d041 | 153 | return 1; |
DaveStyles | 0:b545e012d041 | 154 | } |
DaveStyles | 0:b545e012d041 | 155 | |
DaveStyles | 0:b545e012d041 | 156 | // send the data block |
DaveStyles | 0:b545e012d041 | 157 | _write(buffer, 512); |
DaveStyles | 0:b545e012d041 | 158 | return 0; |
DaveStyles | 0:b545e012d041 | 159 | } |
DaveStyles | 0:b545e012d041 | 160 | |
DaveStyles | 0:b545e012d041 | 161 | int SDFileSystem::disk_read(char *buffer, int block_number) { |
DaveStyles | 0:b545e012d041 | 162 | // set read address for single block (CMD17) |
DaveStyles | 0:b545e012d041 | 163 | if(_cmd(17, block_number * 512) != 0) { |
DaveStyles | 0:b545e012d041 | 164 | return 1; |
DaveStyles | 0:b545e012d041 | 165 | } |
DaveStyles | 0:b545e012d041 | 166 | |
DaveStyles | 0:b545e012d041 | 167 | // receive the data |
DaveStyles | 0:b545e012d041 | 168 | _read(buffer, 512); |
DaveStyles | 0:b545e012d041 | 169 | return 0; |
DaveStyles | 0:b545e012d041 | 170 | } |
DaveStyles | 0:b545e012d041 | 171 | |
DaveStyles | 0:b545e012d041 | 172 | int SDFileSystem::disk_status() { return 0; } |
DaveStyles | 0:b545e012d041 | 173 | int SDFileSystem::disk_sync() { return 0; } |
DaveStyles | 0:b545e012d041 | 174 | int SDFileSystem::disk_sectors() { return _sectors; } |
DaveStyles | 0:b545e012d041 | 175 | |
DaveStyles | 0:b545e012d041 | 176 | // PRIVATE FUNCTIONS |
DaveStyles | 0:b545e012d041 | 177 | |
DaveStyles | 0:b545e012d041 | 178 | int SDFileSystem::_cmd(int cmd, int arg) { |
DaveStyles | 0:b545e012d041 | 179 | _cs = 0; |
DaveStyles | 0:b545e012d041 | 180 | |
DaveStyles | 0:b545e012d041 | 181 | // send a command |
DaveStyles | 0:b545e012d041 | 182 | _spi.write(0x40 | cmd); |
DaveStyles | 0:b545e012d041 | 183 | _spi.write(arg >> 24); |
DaveStyles | 0:b545e012d041 | 184 | _spi.write(arg >> 16); |
DaveStyles | 0:b545e012d041 | 185 | _spi.write(arg >> 8); |
DaveStyles | 0:b545e012d041 | 186 | _spi.write(arg >> 0); |
DaveStyles | 0:b545e012d041 | 187 | _spi.write(0x95); |
DaveStyles | 0:b545e012d041 | 188 | |
DaveStyles | 0:b545e012d041 | 189 | // wait for the repsonse (response[7] == 0) |
DaveStyles | 0:b545e012d041 | 190 | for(int i=0; i<SD_COMMAND_TIMEOUT; i++) { |
DaveStyles | 0:b545e012d041 | 191 | int response = _spi.write(0xFF); |
DaveStyles | 0:b545e012d041 | 192 | if(!(response & 0x80)) { |
DaveStyles | 0:b545e012d041 | 193 | _cs = 1; |
DaveStyles | 0:b545e012d041 | 194 | return response; |
DaveStyles | 0:b545e012d041 | 195 | } |
DaveStyles | 0:b545e012d041 | 196 | } |
DaveStyles | 0:b545e012d041 | 197 | _cs = 1; |
DaveStyles | 0:b545e012d041 | 198 | return -1; // timeout |
DaveStyles | 0:b545e012d041 | 199 | } |
DaveStyles | 0:b545e012d041 | 200 | |
DaveStyles | 0:b545e012d041 | 201 | int SDFileSystem::_read(char *buffer, int length) { |
DaveStyles | 0:b545e012d041 | 202 | _cs = 0; |
DaveStyles | 0:b545e012d041 | 203 | |
DaveStyles | 0:b545e012d041 | 204 | // read until start byte (0xFF) |
DaveStyles | 0:b545e012d041 | 205 | while(_spi.write(0xFF) != 0xFE); |
DaveStyles | 0:b545e012d041 | 206 | |
DaveStyles | 0:b545e012d041 | 207 | // read data |
DaveStyles | 0:b545e012d041 | 208 | for(int i=0; i<length; i++) { |
DaveStyles | 0:b545e012d041 | 209 | buffer[i] = _spi.write(0xFF); |
DaveStyles | 0:b545e012d041 | 210 | } |
DaveStyles | 0:b545e012d041 | 211 | _spi.write(0xFF); // checksum |
DaveStyles | 0:b545e012d041 | 212 | _spi.write(0xFF); |
DaveStyles | 0:b545e012d041 | 213 | |
DaveStyles | 0:b545e012d041 | 214 | _cs = 1; |
DaveStyles | 0:b545e012d041 | 215 | return 0; |
DaveStyles | 0:b545e012d041 | 216 | } |
DaveStyles | 0:b545e012d041 | 217 | |
DaveStyles | 0:b545e012d041 | 218 | int SDFileSystem::_write(const char *buffer, int length) { |
DaveStyles | 0:b545e012d041 | 219 | _cs = 0; |
DaveStyles | 0:b545e012d041 | 220 | |
DaveStyles | 0:b545e012d041 | 221 | // indicate start of block |
DaveStyles | 0:b545e012d041 | 222 | _spi.write(0xFE); |
DaveStyles | 0:b545e012d041 | 223 | |
DaveStyles | 0:b545e012d041 | 224 | // write the data |
DaveStyles | 0:b545e012d041 | 225 | for(int i=0; i<length; i++) { |
DaveStyles | 0:b545e012d041 | 226 | _spi.write(buffer[i]); |
DaveStyles | 0:b545e012d041 | 227 | } |
DaveStyles | 0:b545e012d041 | 228 | |
DaveStyles | 0:b545e012d041 | 229 | // write the checksum |
DaveStyles | 0:b545e012d041 | 230 | _spi.write(0xFF); |
DaveStyles | 0:b545e012d041 | 231 | _spi.write(0xFF); |
DaveStyles | 0:b545e012d041 | 232 | |
DaveStyles | 0:b545e012d041 | 233 | // check the repsonse token |
DaveStyles | 0:b545e012d041 | 234 | if((_spi.write(0xFF) & 0x1F) != 0x05) { |
DaveStyles | 0:b545e012d041 | 235 | _cs = 1; |
DaveStyles | 0:b545e012d041 | 236 | return 1; |
DaveStyles | 0:b545e012d041 | 237 | } |
DaveStyles | 0:b545e012d041 | 238 | |
DaveStyles | 0:b545e012d041 | 239 | // wait for write to finish |
DaveStyles | 0:b545e012d041 | 240 | while(_spi.write(0xFF) == 0); |
DaveStyles | 0:b545e012d041 | 241 | |
DaveStyles | 0:b545e012d041 | 242 | _cs = 1; |
DaveStyles | 0:b545e012d041 | 243 | return 0; |
DaveStyles | 0:b545e012d041 | 244 | } |
DaveStyles | 0:b545e012d041 | 245 | |
DaveStyles | 0:b545e012d041 | 246 | static int ext_bits(char *data, int msb, int lsb) { |
DaveStyles | 0:b545e012d041 | 247 | int bits = 0; |
DaveStyles | 0:b545e012d041 | 248 | int size = 1 + msb - lsb; |
DaveStyles | 0:b545e012d041 | 249 | for(int i=0; i<size; i++) { |
DaveStyles | 0:b545e012d041 | 250 | int position = lsb + i; |
DaveStyles | 0:b545e012d041 | 251 | int byte = 15 - (position >> 3); |
DaveStyles | 0:b545e012d041 | 252 | int bit = position & 0x7; |
DaveStyles | 0:b545e012d041 | 253 | int value = (data[byte] >> bit) & 1; |
DaveStyles | 0:b545e012d041 | 254 | bits |= value << i; |
DaveStyles | 0:b545e012d041 | 255 | } |
DaveStyles | 0:b545e012d041 | 256 | return bits; |
DaveStyles | 0:b545e012d041 | 257 | } |
DaveStyles | 0:b545e012d041 | 258 | |
DaveStyles | 0:b545e012d041 | 259 | int SDFileSystem::_sd_sectors() { |
DaveStyles | 0:b545e012d041 | 260 | |
DaveStyles | 0:b545e012d041 | 261 | // CMD9, Response R2 (R1 byte + 16-byte block read) |
DaveStyles | 0:b545e012d041 | 262 | if(_cmd(9, 0) != 0) { |
DaveStyles | 0:b545e012d041 | 263 | fprintf(stderr, "Didn't get a response from the disk\n"); |
DaveStyles | 0:b545e012d041 | 264 | return 0; |
DaveStyles | 0:b545e012d041 | 265 | } |
DaveStyles | 0:b545e012d041 | 266 | |
DaveStyles | 0:b545e012d041 | 267 | char csd[16]; |
DaveStyles | 0:b545e012d041 | 268 | if(_read(csd, 16) != 0) { |
DaveStyles | 0:b545e012d041 | 269 | fprintf(stderr, "Couldn't read csd response from disk\n"); |
DaveStyles | 0:b545e012d041 | 270 | return 0; |
DaveStyles | 0:b545e012d041 | 271 | } |
DaveStyles | 0:b545e012d041 | 272 | |
DaveStyles | 0:b545e012d041 | 273 | // csd_structure : csd[127:126] |
DaveStyles | 0:b545e012d041 | 274 | // c_size : csd[73:62] |
DaveStyles | 0:b545e012d041 | 275 | // c_size_mult : csd[49:47] |
DaveStyles | 0:b545e012d041 | 276 | // read_bl_len : csd[83:80] |
DaveStyles | 0:b545e012d041 | 277 | |
DaveStyles | 0:b545e012d041 | 278 | int csd_structure = ext_bits(csd, 127, 126); |
DaveStyles | 0:b545e012d041 | 279 | int c_size = ext_bits(csd, 73, 62); |
DaveStyles | 0:b545e012d041 | 280 | int c_size_mult = ext_bits(csd, 49, 47); |
DaveStyles | 0:b545e012d041 | 281 | int read_bl_len = ext_bits(csd, 83, 80); |
DaveStyles | 0:b545e012d041 | 282 | |
DaveStyles | 0:b545e012d041 | 283 | if(csd_structure != 0) { |
DaveStyles | 0:b545e012d041 | 284 | fprintf(stderr, "This disk tastes funny! I only know about type 0 CSD structures"); |
DaveStyles | 0:b545e012d041 | 285 | return 0; |
DaveStyles | 0:b545e012d041 | 286 | } |
DaveStyles | 0:b545e012d041 | 287 | |
DaveStyles | 0:b545e012d041 | 288 | int blocks = (c_size + 1) * (1 << (c_size_mult + 2)); |
DaveStyles | 0:b545e012d041 | 289 | int block_size = 1 << read_bl_len; |
DaveStyles | 0:b545e012d041 | 290 | |
DaveStyles | 0:b545e012d041 | 291 | if(block_size != 512) { |
DaveStyles | 0:b545e012d041 | 292 | fprintf(stderr, "This disk tastes funny! I only like 512-byte blocks"); |
DaveStyles | 0:b545e012d041 | 293 | return 0; |
DaveStyles | 0:b545e012d041 | 294 | } |
DaveStyles | 0:b545e012d041 | 295 | |
DaveStyles | 0:b545e012d041 | 296 | return blocks; |
DaveStyles | 0:b545e012d041 | 297 | } |