Add 'CAN-binder/libs/bitfield-c/' from commit 'a34745ec93ae0a1d4f1b640dba8fb6702331a8e9'

git-subtree-dir: CAN-binder/libs/bitfield-c
git-subtree-mainline: b6c09cbda2b6b47981d65265184a21223e526d4a
git-subtree-split: a34745ec93ae0a1d4f1b640dba8fb6702331a8e9

1 files changed, 220 insertions, 0 deletions

diff --git a/CAN-binder/libs/bitfield-c/src/bitfield/bitfield.h b/CAN-binder/libs/bitfield-c/src/bitfield/bitfield.h
new file mode 100644
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+++ b/CAN-binder/libs/bitfield-c/src/bitfield/bitfield.h
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+#ifndef __BITFIELD_H__
+#define __BITFIELD_H__
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#define NIBBLE_SIZE (CHAR_BIT / 2)
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Public: Reads a subset of bits into a uint64_t, right aligned so they may be
+ * interpreted as a number.
+ *
+ * source - the bytes in question.
+ * source_size - the number of bytes in the source.
+ * offset - the starting index of the bit field (beginning from 0).
+ * bit_count - the width of the bit field to extract. This must be less than or
+ *      equal to 64.
+ *
+ * Bit fields are positioned according to big-endian bit layout and the data is
+ * swapped automatically as necessary depending on the compiled architecture.
+ *
+ * For example, the bit layout of the value "42" (i.e. 00101010 set at position
+ * 14 with length 6 is:
+ *
+ *     000000000000001010100000000000000000000000000000000000000000000
+ *
+ * and the same value and position but with length 8 is:
+ *
+ *     000000000000000010101000000000000000000000000000000000000000000
+ *
+ * Examples
+ *
+ *  uint64_t value = get_bitfield(data, data_size, 2, 4);
+ *
+ * Returns the value of the requested bit field, right aligned in a uint64_t.
+ */
+uint64_t get_bitfield(const uint8_t source[], const uint8_t source_length,
+                const uint16_t offset, const uint16_t bit_count);
+
+/* Public: Return a single nibble from the byte array, with range checking.
+ *
+ * source - the source byte array.
+ * source_length - the total length of the source array.
+ * nibble_index - the index of the nibble to retreive. The leftmost nibble is
+ *      index 0.
+ *
+ * Returns the retreived nibble, right aligned in a uint8_t.
+ */
+uint8_t get_nibble(const uint8_t source[], const uint8_t source_length,
+                const uint8_t nibble_index);
+
+/* Public: Return a single byte from the byte array, with range checking.
+ *
+ * source - the source byte array.
+ * source_length - the total length of the source array.
+ * byte_index - the index of the byte to retreive. The leftmost byte is index 0.
+ *
+ * Returns the retreived byte.
+ */
+uint8_t get_byte(const uint8_t source[], const uint8_t source_length,
+        const uint8_t byte_index);
+
+/* Public: Copy a range of bits from one bit array to another.
+ *
+ * The range does not need to be byte aligned, and the source and destination do
+ * not have to be the same size (as long as the desitnation has enough room to
+ * fit the range).
+ *
+ * A bit array with regards to this function always has the leftmost bit in byte
+ * 0, i.e. bit index is the leftmost bit of byte 0. Endianness does not matter.
+ *
+ * For example:
+ *
+ *      uint8_t source[4] = {0x11, 0x22, 0x33, 0x44};
+ *      uint8_t destination[4] = {0};
+ *      copy_bits(source, sizeof(source), 8, 8, destination,
+ *              sizeof(destination), 0);
+ *      // destination[0] == 0x22
+ *      // destination[1] == 0x0
+ *      // destination[2] == 0x0
+ *      // destination[3] == 0x0
+ *
+ * Thanks to
+ * http://stackoverflow.com/questions/3534535/whats-a-time-efficient-algorithm-to-copy-unaligned-bit-arrays
+ * for the implementation of the algorithm.
+ *
+ * source_origin - the source array.
+ * source_length - the total length of the source array in bytes,
+ *      for range checking.
+ * source_offset - an offset in bits to start the copy from the source array.
+ *      Specify 0 to start from source_origin.
+ * bit_count - the number of bits to copy.
+ * destination_origin - the destination array.
+ * desitnation_length - the total length of the destination array in bytes,
+ *      for range checking.
+ * destination_offset - an offset in bits to start placing the copied range into
+ *      the destination array. Specify 0 to start from the beginning of the
+ *      destination. If you are copying a range not aligned on a byte, you
+ *      probably want to set this to a positive offset to right the resulting
+ *      bits in the destination.
+ *
+ * Returns true if the copy was successful and false if the range exceeded the
+ * size of the source or destination, or if the range size negative or 0.
+ */
+bool copy_bits(const uint8_t* source_origin, const uint16_t source_length,
+        const uint16_t source_offset, uint16_t bit_count,
+        uint8_t* destination_origin, const uint16_t destination_length,
+        const uint16_t destination_offset);
+
+/* Public: Copy a range of bits from one array to another, right aligning the
+ * result.
+ *
+ * This is mostly useful if you want to cast the result to an integer type
+ * instead of a byte array.
+ *
+ * For example:
+ *
+ *      uint8_t source[4] = {0x11, 0x22, 0x33, 0x44};
+ *      uint8_t destination[4] = {0};
+ *      copy_bits_right_aligned(source, sizeof(source), 8, 8, destination,
+ *              sizeof(destination));
+ *      // destination[0] == 0x0
+ *      // destination[1] == 0x0
+ *      // destination[2] == 0x0
+ *      // destination[3] == 0x22
+ *
+ *      int value = (int)destination;
+ *      // value == 0x22 == 32
+ *
+ * The arguments are the same as copy_bits, but without the destination_offset
+ * option - that's set automatically to right align the result.
+ *
+ * Returns true if the copy was successful and false if the range exceeded the
+ * size of the source or destination, or if the range size negative or 0.
+ */
+bool copy_bits_right_aligned(const uint8_t source[], const uint16_t source_length,
+                const uint16_t offset, const uint16_t bit_count,
+                uint8_t* destination, const uint16_t destination_length);
+
+/* Public: Copy a range of bytes from one byte array to another.
+ *
+ * The source and destination do not have to be the same size (as long as the
+ * desitnation has enough room to fit the range).
+ *
+ * source_origin - the source array.
+ * source_length - the total length of the source array in bytes,
+ *      for range checking.
+ * source_offset - a byte offset to start the copy from the source array.
+ *      Specify 0 to start from source_origin.
+ * byte_count - the number of bytes to copy.
+ * destination_origin - the destination array.
+ * desitnation_length - the total length of the destination array in bytes,
+ *      for range checking.
+ * destination_offset - an offset in bytes to start placing the copied range into
+ *      the destination array. Specify 0 to start from the beginning of the
+ *      destination.
+ *
+ * Returns true if the copy was successful and false if the range exceeded the
+ * size of the source or destination, or if the range size negative or 0.
+ */
+bool copy_bytes_right_aligned(const uint8_t source[], const uint16_t source_length,
+                const uint16_t offset, const uint16_t byte_count,
+                uint8_t* destination, const uint16_t destination_length);
+
+/* Public: Set the a nibble in the given data array to the new value.
+ *
+ * nibble_index - the index of the nibble to retreive. The leftmost nibble is
+ *      index 0.
+ * value - the value to set in the bit field.
+ * destination - the destination array.
+ * destination_length - the total length of the destination array in bytes,
+ *      for range checking.
+ *
+ * Returns true if the bit_count is enough to fully represent the value, and
+ *      false if it will not fit.
+ */
+bool set_nibble(const uint16_t nibble_index, const uint8_t value,
+                uint8_t* destination, const uint16_t destination_length);
+
+/* Public: Set the bit field in the given data array to the new value.
+ *
+ * value - the value to set in the bit field.
+ * offset - the starting index of the bit field (beginning from 0).
+ * bit_count - the number of bits to set in the data.
+ * destination - the destination array.
+ * destination_length - the total length of the destination array in bytes,
+ *      for range checking.
+ *
+ * Returns true if the bit_count is enough to fully represent the value, and
+ *      false if it will not fit.
+ */
+bool set_bitfield(const uint64_t value, const uint16_t offset,
+        const uint16_t bit_count, uint8_t destination[],
+        uint16_t destination_length);
+
+/* Public: Return a right aligned bitmask for a uint64_t.
+ *
+ * bit_count - the number of bits to mask, right aligned.
+ */
+uint64_t bitmask(const uint8_t bit_count);
+
+/* Private:
+ */
+uint16_t bits_to_bytes(uint32_t bits);
+
+/* Private: A union to assist swapping between uint64_t and a uint8_t array.
+ */
+typedef union {
+    uint64_t whole;
+    uint8_t bytes[sizeof(uint64_t)];
+} ArrayOrBytes;
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // __BITFIELD_H__