--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sd_raw.c	Tue Jun 25 13:55:11 2013 +0800
@@ -0,0 +1,998 @@
+
+/*
+ * Copyright (c) 2006-2012 by Roland Riegel <[email protected]>
+ *
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of either the GNU General Public License version 2
+ * or the GNU Lesser General Public License version 2.1, both as
+ * published by the Free Software Foundation.
+ */
+
+#include <string.h>
+#include <avr/io.h>
+#include "sd_raw.h"
+
+/**
+ * \addtogroup sd_raw MMC/SD/SDHC card raw access
+ *
+ * This module implements read and write access to MMC, SD
+ * and SDHC cards. It serves as a low-level driver for the
+ * higher level modules such as partition and file system
+ * access.
+ *
+ * @{
+ */
+/**
+ * \file
+ * MMC/SD/SDHC raw access implementation (license: GPLv2 or LGPLv2.1)
+ *
+ * \author Roland Riegel
+ */
+
+/**
+ * \addtogroup sd_raw_config MMC/SD configuration
+ * Preprocessor defines to configure the MMC/SD support.
+ */
+
+/**
+ * @}
+ */
+
+/* commands available in SPI mode */
+
+/* CMD0: response R1 */
+#define CMD_GO_IDLE_STATE 0x00
+/* CMD1: response R1 */
+#define CMD_SEND_OP_COND 0x01
+/* CMD8: response R7 */
+#define CMD_SEND_IF_COND 0x08
+/* CMD9: response R1 */
+#define CMD_SEND_CSD 0x09
+/* CMD10: response R1 */
+#define CMD_SEND_CID 0x0a
+/* CMD12: response R1 */
+#define CMD_STOP_TRANSMISSION 0x0c
+/* CMD13: response R2 */
+#define CMD_SEND_STATUS 0x0d
+/* CMD16: arg0[31:0]: block length, response R1 */
+#define CMD_SET_BLOCKLEN 0x10
+/* CMD17: arg0[31:0]: data address, response R1 */
+#define CMD_READ_SINGLE_BLOCK 0x11
+/* CMD18: arg0[31:0]: data address, response R1 */
+#define CMD_READ_MULTIPLE_BLOCK 0x12
+/* CMD24: arg0[31:0]: data address, response R1 */
+#define CMD_WRITE_SINGLE_BLOCK 0x18
+/* CMD25: arg0[31:0]: data address, response R1 */
+#define CMD_WRITE_MULTIPLE_BLOCK 0x19
+/* CMD27: response R1 */
+#define CMD_PROGRAM_CSD 0x1b
+/* CMD28: arg0[31:0]: data address, response R1b */
+#define CMD_SET_WRITE_PROT 0x1c
+/* CMD29: arg0[31:0]: data address, response R1b */
+#define CMD_CLR_WRITE_PROT 0x1d
+/* CMD30: arg0[31:0]: write protect data address, response R1 */
+#define CMD_SEND_WRITE_PROT 0x1e
+/* CMD32: arg0[31:0]: data address, response R1 */
+#define CMD_TAG_SECTOR_START 0x20
+/* CMD33: arg0[31:0]: data address, response R1 */
+#define CMD_TAG_SECTOR_END 0x21
+/* CMD34: arg0[31:0]: data address, response R1 */
+#define CMD_UNTAG_SECTOR 0x22
+/* CMD35: arg0[31:0]: data address, response R1 */
+#define CMD_TAG_ERASE_GROUP_START 0x23
+/* CMD36: arg0[31:0]: data address, response R1 */
+#define CMD_TAG_ERASE_GROUP_END 0x24
+/* CMD37: arg0[31:0]: data address, response R1 */
+#define CMD_UNTAG_ERASE_GROUP 0x25
+/* CMD38: arg0[31:0]: stuff bits, response R1b */
+#define CMD_ERASE 0x26
+/* ACMD41: arg0[31:0]: OCR contents, response R1 */
+#define CMD_SD_SEND_OP_COND 0x29
+/* CMD42: arg0[31:0]: stuff bits, response R1b */
+#define CMD_LOCK_UNLOCK 0x2a
+/* CMD55: arg0[31:0]: stuff bits, response R1 */
+#define CMD_APP 0x37
+/* CMD58: arg0[31:0]: stuff bits, response R3 */
+#define CMD_READ_OCR 0x3a
+/* CMD59: arg0[31:1]: stuff bits, arg0[0:0]: crc option, response R1 */
+#define CMD_CRC_ON_OFF 0x3b
+
+/* command responses */
+/* R1: size 1 byte */
+#define R1_IDLE_STATE 0
+#define R1_ERASE_RESET 1
+#define R1_ILL_COMMAND 2
+#define R1_COM_CRC_ERR 3
+#define R1_ERASE_SEQ_ERR 4
+#define R1_ADDR_ERR 5
+#define R1_PARAM_ERR 6
+/* R1b: equals R1, additional busy bytes */
+/* R2: size 2 bytes */
+#define R2_CARD_LOCKED 0
+#define R2_WP_ERASE_SKIP 1
+#define R2_ERR 2
+#define R2_CARD_ERR 3
+#define R2_CARD_ECC_FAIL 4
+#define R2_WP_VIOLATION 5
+#define R2_INVAL_ERASE 6
+#define R2_OUT_OF_RANGE 7
+#define R2_CSD_OVERWRITE 7
+#define R2_IDLE_STATE (R1_IDLE_STATE + 8)
+#define R2_ERASE_RESET (R1_ERASE_RESET + 8)
+#define R2_ILL_COMMAND (R1_ILL_COMMAND + 8)
+#define R2_COM_CRC_ERR (R1_COM_CRC_ERR + 8)
+#define R2_ERASE_SEQ_ERR (R1_ERASE_SEQ_ERR + 8)
+#define R2_ADDR_ERR (R1_ADDR_ERR + 8)
+#define R2_PARAM_ERR (R1_PARAM_ERR + 8)
+/* R3: size 5 bytes */
+#define R3_OCR_MASK (0xffffffffUL)
+#define R3_IDLE_STATE (R1_IDLE_STATE + 32)
+#define R3_ERASE_RESET (R1_ERASE_RESET + 32)
+#define R3_ILL_COMMAND (R1_ILL_COMMAND + 32)
+#define R3_COM_CRC_ERR (R1_COM_CRC_ERR + 32)
+#define R3_ERASE_SEQ_ERR (R1_ERASE_SEQ_ERR + 32)
+#define R3_ADDR_ERR (R1_ADDR_ERR + 32)
+#define R3_PARAM_ERR (R1_PARAM_ERR + 32)
+/* Data Response: size 1 byte */
+#define DR_STATUS_MASK 0x0e
+#define DR_STATUS_ACCEPTED 0x05
+#define DR_STATUS_CRC_ERR 0x0a
+#define DR_STATUS_WRITE_ERR 0x0c
+
+/* status bits for card types */
+#define SD_RAW_SPEC_1 0
+#define SD_RAW_SPEC_2 1
+#define SD_RAW_SPEC_SDHC 2
+
+#if !SD_RAW_SAVE_RAM
+/* static data buffer for acceleration */
+static uint8_t raw_block[512];
+/* offset where the data within raw_block lies on the card */
+static offset_t raw_block_address;
+#if SD_RAW_WRITE_BUFFERING
+/* flag to remember if raw_block was written to the card */
+static uint8_t raw_block_written;
+#endif
+#endif
+
+/* card type state */
+static uint8_t sd_raw_card_type;
+
+/* private helper functions */
+static void sd_raw_send_byte(uint8_t b);
+static uint8_t sd_raw_rec_byte();
+static uint8_t sd_raw_send_command(uint8_t command, uint32_t arg);
+
+/**
+ * \ingroup sd_raw
+ * Initializes memory card communication.
+ *
+ * \returns 0 on failure, 1 on success.
+ */
+uint8_t sd_raw_init()
+{
+    /* enable inputs for reading card status */
+    configure_pin_available();
+    configure_pin_locked();
+
+    /* enable outputs for MOSI, SCK, SS, input for MISO */
+    configure_pin_mosi();
+    configure_pin_sck();
+    configure_pin_ss();
+    configure_pin_miso();
+
+    unselect_card();
+
+    /* initialize SPI with lowest frequency; max. 400kHz during identification mode of card */
+    SPCR = (0 << SPIE) | /* SPI Interrupt Enable */
+           (1 << SPE)  | /* SPI Enable */
+           (0 << DORD) | /* Data Order: MSB first */
+           (1 << MSTR) | /* Master mode */
+           (0 << CPOL) | /* Clock Polarity: SCK low when idle */
+           (0 << CPHA) | /* Clock Phase: sample on rising SCK edge */
+           (1 << SPR1) | /* Clock Frequency: f_OSC / 128 */
+           (1 << SPR0);
+    SPSR &= ~(1 << SPI2X); /* No doubled clock frequency */
+
+    /* initialization procedure */
+    sd_raw_card_type = 0;
+    
+    if(!sd_raw_available())
+        return 0;
+
+    /* card needs 74 cycles minimum to start up */
+    for(uint8_t i = 0; i < 10; ++i)
+    {
+        /* wait 8 clock cycles */
+        sd_raw_rec_byte();
+    }
+
+    /* address card */
+    select_card();
+
+    /* reset card */
+    uint8_t response;
+    for(uint16_t i = 0; ; ++i)
+    {
+        response = sd_raw_send_command(CMD_GO_IDLE_STATE, 0);
+        if(response == (1 << R1_IDLE_STATE))
+            break;
+
+        if(i == 0x1ff)
+        {
+            unselect_card();
+            return 0;
+        }
+    }
+
+#if SD_RAW_SDHC
+    /* check for version of SD card specification */
+    response = sd_raw_send_command(CMD_SEND_IF_COND, 0x100 /* 2.7V - 3.6V */ | 0xaa /* test pattern */);
+    if((response & (1 << R1_ILL_COMMAND)) == 0)
+    {
+        sd_raw_rec_byte();
+        sd_raw_rec_byte();
+        if((sd_raw_rec_byte() & 0x01) == 0)
+            return 0; /* card operation voltage range doesn't match */
+        if(sd_raw_rec_byte() != 0xaa)
+            return 0; /* wrong test pattern */
+
+        /* card conforms to SD 2 card specification */
+        sd_raw_card_type |= (1 << SD_RAW_SPEC_2);
+    }
+    else
+#endif
+    {
+        /* determine SD/MMC card type */
+        sd_raw_send_command(CMD_APP, 0);
+        response = sd_raw_send_command(CMD_SD_SEND_OP_COND, 0);
+        if((response & (1 << R1_ILL_COMMAND)) == 0)
+        {
+            /* card conforms to SD 1 card specification */
+            sd_raw_card_type |= (1 << SD_RAW_SPEC_1);
+        }
+        else
+        {
+            /* MMC card */
+        }
+    }
+
+    /* wait for card to get ready */
+    for(uint16_t i = 0; ; ++i)
+    {
+        if(sd_raw_card_type & ((1 << SD_RAW_SPEC_1) | (1 << SD_RAW_SPEC_2)))
+        {
+            uint32_t arg = 0;
+#if SD_RAW_SDHC
+            if(sd_raw_card_type & (1 << SD_RAW_SPEC_2))
+                arg = 0x40000000;
+#endif
+            sd_raw_send_command(CMD_APP, 0);
+            response = sd_raw_send_command(CMD_SD_SEND_OP_COND, arg);
+        }
+        else
+        {
+            response = sd_raw_send_command(CMD_SEND_OP_COND, 0);
+        }
+
+        if((response & (1 << R1_IDLE_STATE)) == 0)
+            break;
+
+        if(i == 0x7fff)
+        {
+            unselect_card();
+            return 0;
+        }
+    }
+
+#if SD_RAW_SDHC
+    if(sd_raw_card_type & (1 << SD_RAW_SPEC_2))
+    {
+        if(sd_raw_send_command(CMD_READ_OCR, 0))
+        {
+            unselect_card();
+            return 0;
+        }
+
+        if(sd_raw_rec_byte() & 0x40)
+            sd_raw_card_type |= (1 << SD_RAW_SPEC_SDHC);
+
+        sd_raw_rec_byte();
+        sd_raw_rec_byte();
+        sd_raw_rec_byte();
+    }
+#endif
+
+    /* set block size to 512 bytes */
+    if(sd_raw_send_command(CMD_SET_BLOCKLEN, 512))
+    {
+        unselect_card();
+        return 0;
+    }
+
+    /* deaddress card */
+    unselect_card();
+
+    /* switch to highest SPI frequency possible */
+    SPCR &= ~((1 << SPR1) | (1 << SPR0)); /* Clock Frequency: f_OSC / 4 */
+    SPSR |= (1 << SPI2X); /* Doubled Clock Frequency: f_OSC / 2 */
+
+#if !SD_RAW_SAVE_RAM
+    /* the first block is likely to be accessed first, so precache it here */
+    raw_block_address = (offset_t) -1;
+#if SD_RAW_WRITE_BUFFERING
+    raw_block_written = 1;
+#endif
+    if(!sd_raw_read(0, raw_block, sizeof(raw_block)))
+        return 0;
+#endif
+
+    return 1;
+}
+
+/**
+ * \ingroup sd_raw
+ * Checks wether a memory card is located in the slot.
+ *
+ * \returns 1 if the card is available, 0 if it is not.
+ */
+uint8_t sd_raw_available()
+{
+    return get_pin_available() == 0x00;
+}
+
+/**
+ * \ingroup sd_raw
+ * Checks wether the memory card is locked for write access.
+ *
+ * \returns 1 if the card is locked, 0 if it is not.
+ */
+uint8_t sd_raw_locked()
+{
+    return get_pin_locked() == 0x00;
+}
+
+/**
+ * \ingroup sd_raw
+ * Sends a raw byte to the memory card.
+ *
+ * \param[in] b The byte to sent.
+ * \see sd_raw_rec_byte
+ */
+void sd_raw_send_byte(uint8_t b)
+{
+    SPDR = b;
+    /* wait for byte to be shifted out */
+    while(!(SPSR & (1 << SPIF)));
+    SPSR &= ~(1 << SPIF);
+}
+
+/**
+ * \ingroup sd_raw
+ * Receives a raw byte from the memory card.
+ *
+ * \returns The byte which should be read.
+ * \see sd_raw_send_byte
+ */
+uint8_t sd_raw_rec_byte()
+{
+    /* send dummy data for receiving some */
+    SPDR = 0xff;
+    while(!(SPSR & (1 << SPIF)));
+    SPSR &= ~(1 << SPIF);
+
+    return SPDR;
+}
+
+/**
+ * \ingroup sd_raw
+ * Send a command to the memory card which responses with a R1 response (and possibly others).
+ *
+ * \param[in] command The command to send.
+ * \param[in] arg The argument for command.
+ * \returns The command answer.
+ */
+uint8_t sd_raw_send_command(uint8_t command, uint32_t arg)
+{
+    uint8_t response;
+
+    /* wait some clock cycles */
+    sd_raw_rec_byte();
+
+    /* send command via SPI */
+    sd_raw_send_byte(0x40 | command);
+    sd_raw_send_byte((arg >> 24) & 0xff);
+    sd_raw_send_byte((arg >> 16) & 0xff);
+    sd_raw_send_byte((arg >> 8) & 0xff);
+    sd_raw_send_byte((arg >> 0) & 0xff);
+    switch(command)
+    {
+        case CMD_GO_IDLE_STATE:
+           sd_raw_send_byte(0x95);
+           break;
+        case CMD_SEND_IF_COND:
+           sd_raw_send_byte(0x87);
+           break;
+        default:
+           sd_raw_send_byte(0xff);
+           break;
+    }
+    
+    /* receive response */
+    for(uint8_t i = 0; i < 10; ++i)
+    {
+        response = sd_raw_rec_byte();
+        if(response != 0xff)
+            break;
+    }
+
+    return response;
+}
+
+/**
+ * \ingroup sd_raw
+ * Reads raw data from the card.
+ *
+ * \param[in] offset The offset from which to read.
+ * \param[out] buffer The buffer into which to write the data.
+ * \param[in] length The number of bytes to read.
+ * \returns 0 on failure, 1 on success.
+ * \see sd_raw_read_interval, sd_raw_write, sd_raw_write_interval
+ */
+uint8_t sd_raw_read(offset_t offset, uint8_t* buffer, uintptr_t length)
+{
+    offset_t block_address;
+    uint16_t block_offset;
+    uint16_t read_length;
+    while(length > 0)
+    {
+        /* determine byte count to read at once */
+        block_offset = offset & 0x01ff;
+        block_address = offset - block_offset;
+        read_length = 512 - block_offset; /* read up to block border */
+        if(read_length > length)
+            read_length = length;
+        
+#if !SD_RAW_SAVE_RAM
+        /* check if the requested data is cached */
+        if(block_address != raw_block_address)
+#endif
+        {
+#if SD_RAW_WRITE_BUFFERING
+            if(!sd_raw_sync())
+                return 0;
+#endif
+
+            /* address card */
+            select_card();
+
+            /* send single block request */
+#if SD_RAW_SDHC
+            if(sd_raw_send_command(CMD_READ_SINGLE_BLOCK, (sd_raw_card_type & (1 << SD_RAW_SPEC_SDHC) ? block_address / 512 : block_address)))
+#else
+            if(sd_raw_send_command(CMD_READ_SINGLE_BLOCK, block_address))
+#endif
+            {
+                unselect_card();
+                return 0;
+            }
+
+            /* wait for data block (start byte 0xfe) */
+            while(sd_raw_rec_byte() != 0xfe);
+
+#if SD_RAW_SAVE_RAM
+            /* read byte block */
+            uint16_t read_to = block_offset + read_length;
+            for(uint16_t i = 0; i < 512; ++i)
+            {
+                uint8_t b = sd_raw_rec_byte();
+                if(i >= block_offset && i < read_to)
+                    *buffer++ = b;
+            }
+#else
+            /* read byte block */
+            uint8_t* cache = raw_block;
+            for(uint16_t i = 0; i < 512; ++i)
+                *cache++ = sd_raw_rec_byte();
+            raw_block_address = block_address;
+
+            memcpy(buffer, raw_block + block_offset, read_length);
+            buffer += read_length;
+#endif
+            
+            /* read crc16 */
+            sd_raw_rec_byte();
+            sd_raw_rec_byte();
+            
+            /* deaddress card */
+            unselect_card();
+
+            /* let card some time to finish */
+            sd_raw_rec_byte();
+        }
+#if !SD_RAW_SAVE_RAM
+        else
+        {
+            /* use cached data */
+            memcpy(buffer, raw_block + block_offset, read_length);
+            buffer += read_length;
+        }
+#endif
+
+        length -= read_length;
+        offset += read_length;
+    }
+
+    return 1;
+}
+
+/**
+ * \ingroup sd_raw
+ * Continuously reads units of \c interval bytes and calls a callback function.
+ *
+ * This function starts reading at the specified offset. Every \c interval bytes,
+ * it calls the callback function with the associated data buffer.
+ *
+ * By returning zero, the callback may stop reading.
+ *
+ * \note Within the callback function, you can not start another read or
+ *       write operation.
+ * \note This function only works if the following conditions are met:
+ *       - (offset - (offset % 512)) % interval == 0
+ *       - length % interval == 0
+ *
+ * \param[in] offset Offset from which to start reading.
+ * \param[in] buffer Pointer to a buffer which is at least interval bytes in size.
+ * \param[in] interval Number of bytes to read before calling the callback function.
+ * \param[in] length Number of bytes to read altogether.
+ * \param[in] callback The function to call every interval bytes.
+ * \param[in] p An opaque pointer directly passed to the callback function.
+ * \returns 0 on failure, 1 on success
+ * \see sd_raw_write_interval, sd_raw_read, sd_raw_write
+ */
+uint8_t sd_raw_read_interval(offset_t offset, uint8_t* buffer, uintptr_t interval, uintptr_t length, sd_raw_read_interval_handler_t callback, void* p)
+{
+    if(!buffer || interval == 0 || length < interval || !callback)
+        return 0;
+
+#if !SD_RAW_SAVE_RAM
+    while(length >= interval)
+    {
+        /* as reading is now buffered, we directly
+         * hand over the request to sd_raw_read()
+         */
+        if(!sd_raw_read(offset, buffer, interval))
+            return 0;
+        if(!callback(buffer, offset, p))
+            break;
+        offset += interval;
+        length -= interval;
+    }
+
+    return 1;
+#else
+    /* address card */
+    select_card();
+
+    uint16_t block_offset;
+    uint16_t read_length;
+    uint8_t* buffer_cur;
+    uint8_t finished = 0;
+    do
+    {
+        /* determine byte count to read at once */
+        block_offset = offset & 0x01ff;
+        read_length = 512 - block_offset;
+        
+        /* send single block request */
+#if SD_RAW_SDHC
+        if(sd_raw_send_command(CMD_READ_SINGLE_BLOCK, (sd_raw_card_type & (1 << SD_RAW_SPEC_SDHC) ? offset / 512 : offset - block_offset)))
+#else
+        if(sd_raw_send_command(CMD_READ_SINGLE_BLOCK, offset - block_offset))
+#endif
+        {
+            unselect_card();
+            return 0;
+        }
+
+        /* wait for data block (start byte 0xfe) */
+        while(sd_raw_rec_byte() != 0xfe);
+
+        /* read up to the data of interest */
+        for(uint16_t i = 0; i < block_offset; ++i)
+            sd_raw_rec_byte();
+
+        /* read interval bytes of data and execute the callback */
+        do
+        {
+            if(read_length < interval || length < interval)
+                break;
+
+            buffer_cur = buffer;
+            for(uint16_t i = 0; i < interval; ++i)
+                *buffer_cur++ = sd_raw_rec_byte();
+
+            if(!callback(buffer, offset + (512 - read_length), p))
+            {
+                finished = 1;
+                break;
+            }
+
+            read_length -= interval;
+            length -= interval;
+
+        } while(read_length > 0 && length > 0);
+        
+        /* read rest of data block */
+        while(read_length-- > 0)
+            sd_raw_rec_byte();
+        
+        /* read crc16 */
+        sd_raw_rec_byte();
+        sd_raw_rec_byte();
+
+        if(length < interval)
+            break;
+
+        offset = offset - block_offset + 512;
+
+    } while(!finished);
+    
+    /* deaddress card */
+    unselect_card();
+
+    /* let card some time to finish */
+    sd_raw_rec_byte();
+
+    return 1;
+#endif
+}
+
+#if DOXYGEN || SD_RAW_WRITE_SUPPORT
+/**
+ * \ingroup sd_raw
+ * Writes raw data to the card.
+ *
+ * \note If write buffering is enabled, you might have to
+ *       call sd_raw_sync() before disconnecting the card
+ *       to ensure all remaining data has been written.
+ *
+ * \param[in] offset The offset where to start writing.
+ * \param[in] buffer The buffer containing the data to be written.
+ * \param[in] length The number of bytes to write.
+ * \returns 0 on failure, 1 on success.
+ * \see sd_raw_write_interval, sd_raw_read, sd_raw_read_interval
+ */
+uint8_t sd_raw_write(offset_t offset, const uint8_t* buffer, uintptr_t length)
+{
+    if(sd_raw_locked())
+        return 0;
+
+    offset_t block_address;
+    uint16_t block_offset;
+    uint16_t write_length;
+    while(length > 0)
+    {
+        /* determine byte count to write at once */
+        block_offset = offset & 0x01ff;
+        block_address = offset - block_offset;
+        write_length = 512 - block_offset; /* write up to block border */
+        if(write_length > length)
+            write_length = length;
+        
+        /* Merge the data to write with the content of the block.
+         * Use the cached block if available.
+         */
+        if(block_address != raw_block_address)
+        {
+#if SD_RAW_WRITE_BUFFERING
+            if(!sd_raw_sync())
+                return 0;
+#endif
+
+            if(block_offset || write_length < 512)
+            {
+                if(!sd_raw_read(block_address, raw_block, sizeof(raw_block)))
+                    return 0;
+            }
+            raw_block_address = block_address;
+        }
+
+        if(buffer != raw_block)
+        {
+            memcpy(raw_block + block_offset, buffer, write_length);
+
+#if SD_RAW_WRITE_BUFFERING
+            raw_block_written = 0;
+
+            if(length == write_length)
+                return 1;
+#endif
+        }
+
+        /* address card */
+        select_card();
+
+        /* send single block request */
+#if SD_RAW_SDHC
+        if(sd_raw_send_command(CMD_WRITE_SINGLE_BLOCK, (sd_raw_card_type & (1 << SD_RAW_SPEC_SDHC) ? block_address / 512 : block_address)))
+#else
+        if(sd_raw_send_command(CMD_WRITE_SINGLE_BLOCK, block_address))
+#endif
+        {
+            unselect_card();
+            return 0;
+        }
+
+        /* send start byte */
+        sd_raw_send_byte(0xfe);
+
+        /* write byte block */
+        uint8_t* cache = raw_block;
+        for(uint16_t i = 0; i < 512; ++i)
+            sd_raw_send_byte(*cache++);
+
+        /* write dummy crc16 */
+        sd_raw_send_byte(0xff);
+        sd_raw_send_byte(0xff);
+
+        /* wait while card is busy */
+        while(sd_raw_rec_byte() != 0xff);
+        sd_raw_rec_byte();
+
+        /* deaddress card */
+        unselect_card();
+
+        buffer += write_length;
+        offset += write_length;
+        length -= write_length;
+
+#if SD_RAW_WRITE_BUFFERING
+        raw_block_written = 1;
+#endif
+    }
+
+    return 1;
+}
+#endif
+
+#if DOXYGEN || SD_RAW_WRITE_SUPPORT
+/**
+ * \ingroup sd_raw
+ * Writes a continuous data stream obtained from a callback function.
+ *
+ * This function starts writing at the specified offset. To obtain the
+ * next bytes to write, it calls the callback function. The callback fills the
+ * provided data buffer and returns the number of bytes it has put into the buffer.
+ *
+ * By returning zero, the callback may stop writing.
+ *
+ * \param[in] offset Offset where to start writing.
+ * \param[in] buffer Pointer to a buffer which is used for the callback function.
+ * \param[in] length Number of bytes to write in total. May be zero for endless writes.
+ * \param[in] callback The function used to obtain the bytes to write.
+ * \param[in] p An opaque pointer directly passed to the callback function.
+ * \returns 0 on failure, 1 on success
+ * \see sd_raw_read_interval, sd_raw_write, sd_raw_read
+ */
+uint8_t sd_raw_write_interval(offset_t offset, uint8_t* buffer, uintptr_t length, sd_raw_write_interval_handler_t callback, void* p)
+{
+#if SD_RAW_SAVE_RAM
+    #error "SD_RAW_WRITE_SUPPORT is not supported together with SD_RAW_SAVE_RAM"
+#endif
+
+    if(!buffer || !callback)
+        return 0;
+
+    uint8_t endless = (length == 0);
+    while(endless || length > 0)
+    {
+        uint16_t bytes_to_write = callback(buffer, offset, p);
+        if(!bytes_to_write)
+            break;
+        if(!endless && bytes_to_write > length)
+            return 0;
+
+        /* as writing is always buffered, we directly
+         * hand over the request to sd_raw_write()
+         */
+        if(!sd_raw_write(offset, buffer, bytes_to_write))
+            return 0;
+
+        offset += bytes_to_write;
+        length -= bytes_to_write;
+    }
+
+    return 1;
+}
+#endif
+
+#if DOXYGEN || SD_RAW_WRITE_SUPPORT
+/**
+ * \ingroup sd_raw
+ * Writes the write buffer's content to the card.
+ *
+ * \note When write buffering is enabled, you should
+ *       call this function before disconnecting the
+ *       card to ensure all remaining data has been
+ *       written.
+ *
+ * \returns 0 on failure, 1 on success.
+ * \see sd_raw_write
+ */
+uint8_t sd_raw_sync()
+{
+#if SD_RAW_WRITE_BUFFERING
+    if(raw_block_written)
+        return 1;
+    if(!sd_raw_write(raw_block_address, raw_block, sizeof(raw_block)))
+        return 0;
+    raw_block_written = 1;
+#endif
+    return 1;
+}
+#endif
+
+/**
+ * \ingroup sd_raw
+ * Reads informational data from the card.
+ *
+ * This function reads and returns the card's registers
+ * containing manufacturing and status information.
+ *
+ * \note: The information retrieved by this function is
+ *        not required in any way to operate on the card,
+ *        but it might be nice to display some of the data
+ *        to the user.
+ *
+ * \param[in] info A pointer to the structure into which to save the information.
+ * \returns 0 on failure, 1 on success.
+ */
+uint8_t sd_raw_get_info(struct sd_raw_info* info)
+{
+    if(!info || !sd_raw_available())
+        return 0;
+
+    memset(info, 0, sizeof(*info));
+
+    select_card();
+
+    /* read cid register */
+    if(sd_raw_send_command(CMD_SEND_CID, 0))
+    {
+        unselect_card();
+        return 0;
+    }
+    while(sd_raw_rec_byte() != 0xfe);
+    for(uint8_t i = 0; i < 18; ++i)
+    {
+        uint8_t b = sd_raw_rec_byte();
+
+        switch(i)
+        {
+            case 0:
+                info->manufacturer = b;
+                break;
+            case 1:
+            case 2:
+                info->oem[i - 1] = b;
+                break;
+            case 3:
+            case 4:
+            case 5:
+            case 6:
+            case 7:
+                info->product[i - 3] = b;
+                break;
+            case 8:
+                info->revision = b;
+                break;
+            case 9:
+            case 10:
+            case 11:
+            case 12:
+                info->serial |= (uint32_t) b << ((12 - i) * 8);
+                break;
+            case 13:
+                info->manufacturing_year = b << 4;
+                break;
+            case 14:
+                info->manufacturing_year |= b >> 4;
+                info->manufacturing_month = b & 0x0f;
+                break;
+        }
+    }
+
+    /* read csd register */
+    uint8_t csd_read_bl_len = 0;
+    uint8_t csd_c_size_mult = 0;
+#if SD_RAW_SDHC
+    uint16_t csd_c_size = 0;
+#else
+    uint32_t csd_c_size = 0;
+#endif
+    uint8_t csd_structure = 0;
+    if(sd_raw_send_command(CMD_SEND_CSD, 0))
+    {
+        unselect_card();
+        return 0;
+    }
+    while(sd_raw_rec_byte() != 0xfe);
+    for(uint8_t i = 0; i < 18; ++i)
+    {
+        uint8_t b = sd_raw_rec_byte();
+
+        if(i == 0)
+        {
+            csd_structure = b >> 6;
+        }
+        else if(i == 14)
+        {
+            if(b & 0x40)
+                info->flag_copy = 1;
+            if(b & 0x20)
+                info->flag_write_protect = 1;
+            if(b & 0x10)
+                info->flag_write_protect_temp = 1;
+            info->format = (b & 0x0c) >> 2;
+        }
+        else
+        {
+#if SD_RAW_SDHC
+            if(csd_structure == 0x01)
+            {
+                switch(i)
+                {
+                    case 7:
+                        b &= 0x3f;
+                    case 8:
+                    case 9:
+                        csd_c_size <<= 8;
+                        csd_c_size |= b;
+                        break;
+                }
+                if(i == 9)
+                {
+                    ++csd_c_size;
+                    info->capacity = (offset_t) csd_c_size * 512 * 1024;
+                }
+            }
+            else if(csd_structure == 0x00)
+#endif
+            {
+                switch(i)
+                {
+                    case 5:
+                        csd_read_bl_len = b & 0x0f;
+                        break;
+                    case 6:
+                        csd_c_size = b & 0x03;
+                        csd_c_size <<= 8;
+                        break;
+                    case 7:
+                        csd_c_size |= b;
+                        csd_c_size <<= 2;
+                        break;
+                    case 8:
+                        csd_c_size |= b >> 6;
+                        ++csd_c_size;
+                        break;
+                    case 9:
+                        csd_c_size_mult = b & 0x03;
+                        csd_c_size_mult <<= 1;
+                        break;
+                    case 10:
+                        csd_c_size_mult |= b >> 7;
+
+                        info->capacity = (uint32_t) csd_c_size << (csd_c_size_mult + csd_read_bl_len + 2);
+                        break;
+                }
+            }
+        }
+    }
+
+    unselect_card();
+
+    return 1;
+}
+