Add FAT16 library

[rmslog.git] / FAT16 / partition.c

diff --git a/FAT16/partition.c b/FAT16/partition.c
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+
+/*
+ * Copyright (c) 2006-2009 by Roland Riegel <feedback@roland-riegel.de>
+ *
+ * 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 "partition.h"
+#include "partition_config.h"
+#include "sd-reader_config.h"
+
+#include <string.h>
+
+#if USE_DYNAMIC_MEMORY
+    #include <stdlib.h>
+#endif
+
+/**
+ * \addtogroup partition Partition table support
+ *
+ * Support for reading partition tables and access to partitions.
+ *
+ * @{
+ */
+/**
+ * \file
+ * Partition table implementation (license: GPLv2 or LGPLv2.1)
+ *
+ * \author Roland Riegel
+ */
+
+/**
+ * \addtogroup partition_config Configuration of partition table support
+ * Preprocessor defines to configure the partition support.
+ */
+
+#if !USE_DYNAMIC_MEMORY
+static struct partition_struct partition_handles[PARTITION_COUNT];
+#endif
+
+/**
+ * Opens a partition.
+ *
+ * Opens a partition by its index number and returns a partition
+ * handle which describes the opened partition.
+ *
+ * \note This function does not support extended partitions.
+ *
+ * \param[in] device_read A function pointer which is used to read from the disk.
+ * \param[in] device_read_interval A function pointer which is used to read in constant intervals from the disk.
+ * \param[in] device_write A function pointer which is used to write to the disk.
+ * \param[in] device_write_interval A function pointer which is used to write a data stream to disk.
+ * \param[in] index The index of the partition which should be opened, range 0 to 3.
+ *                  A negative value is allowed as well. In this case, the partition opened is
+ *                  not checked for existance, begins at offset zero, has a length of zero
+ *                  and is of an unknown type. Use this in case you want to open the whole device
+ *                  as a single partition (e.g. for "super floppy" use).
+ * \returns 0 on failure, a partition descriptor on success.
+ * \see partition_close
+ */
+struct partition_struct* partition_open(device_read_t device_read, device_read_interval_t device_read_interval, device_write_t device_write, device_write_interval_t device_write_interval, int8_t index)
+{
+    struct partition_struct* new_partition = 0;
+    uint8_t buffer[0x10];
+
+    if(!device_read || !device_read_interval || index >= 4)
+        return 0;
+
+    if(index >= 0)
+    {
+        /* read specified partition table index */
+        if(!device_read(0x01be + index * 0x10, buffer, sizeof(buffer)))
+            return 0;
+
+        /* abort on empty partition entry */
+        if(buffer[4] == 0x00)
+            return 0;
+    }
+
+    /* allocate partition descriptor */
+#if USE_DYNAMIC_MEMORY
+    new_partition = malloc(sizeof(*new_partition));
+    if(!new_partition)
+        return 0;
+#else
+    new_partition = partition_handles;
+    uint8_t i;
+    for(i = 0; i < PARTITION_COUNT; ++i)
+    {
+        if(new_partition->type == PARTITION_TYPE_FREE)
+            break;
+
+        ++new_partition;
+    }
+    if(i >= PARTITION_COUNT)
+        return 0;
+#endif
+
+    memset(new_partition, 0, sizeof(*new_partition));
+
+    /* fill partition descriptor */
+    new_partition->device_read = device_read;
+    new_partition->device_read_interval = device_read_interval;
+    new_partition->device_write = device_write;
+    new_partition->device_write_interval = device_write_interval;
+
+    if(index >= 0)
+    {
+        new_partition->type = buffer[4];
+        new_partition->offset = ((uint32_t) buffer[8]) |
+                                ((uint32_t) buffer[9] << 8) |
+                                ((uint32_t) buffer[10] << 16) |
+                                ((uint32_t) buffer[11] << 24);
+        new_partition->length = ((uint32_t) buffer[12]) |
+                                ((uint32_t) buffer[13] << 8) |
+                                ((uint32_t) buffer[14] << 16) |
+                                ((uint32_t) buffer[15] << 24);
+    }
+    else
+    {
+        new_partition->type = 0xff;
+    }
+
+    return new_partition;
+}
+
+/**
+ * Closes a partition.
+ *
+ * This function destroys a partition descriptor which was
+ * previously obtained from a call to partition_open().
+ * When this function returns, the given descriptor will be
+ * invalid.
+ *
+ * \param[in] partition The partition descriptor to destroy.
+ * \returns 0 on failure, 1 on success.
+ * \see partition_open
+ */
+uint8_t partition_close(struct partition_struct* partition)
+{
+    if(!partition)
+        return 0;
+
+    /* destroy partition descriptor */
+#if USE_DYNAMIC_MEMORY
+    free(partition);
+#else
+    partition->type = PARTITION_TYPE_FREE;
+#endif
+
+    return 1;
+}
+
+/**
+ * @}
+ */
+