-CAN Message Utilities for C
+Bitfield Utilities in C
===========================
This is a C library with functions to help encode and decode Controller Area
-Network (CAN) message payloads. Some of the bitfield functions may be useful for
-other areas, too.
+Network (CAN) message payloads or other bitfields.
The header files contain complete function documentation, but to get you
started, here are examples using the API:
## Bitfield Manipulation
+The bitfields are stored in `uint8_t[]`.
+
uint8_t data[4] = {0x12, 0x34, 0x56, 0x78};
- uint8_t result = getByte(data, sizeof(data), 0);
- uint8_t result = getNibble(data, sizeof(data), 0);
- fail_unless(copyBitsRightAligned(data, 4, 4, 12, result, 4));
+ uint8_t result = get_byte(data, sizeof(data), 0);
+ // result = 0x12;
+ result = get_nibble(data, sizeof(data), 0);
+ // result = 0x1;
+ bool success = copy_bits_right_aligned(data, 4, 4, 12, result, 4)
+ // success == true
+ // result[0] == 0x2
+ // result[1] == 0x34
+
+## 8 Byte Helpers
+
+If you are dealing with 8 byte CAN messages as `uint64_t`, there are some
+additional functions prefixed with `eightbyte_` that may be faster or more
+useful.
-## 8 Byte Bitfield Decoding
+### 8 Byte Decoding
uint64_t data = 0x8000000000000000;
uint64_t result = get_bit_field(data, 0, 1, false);
// result = 0x574d555a;
data = 0x00000000F34DFCFF;
- result = nth_byte(data, 0);
+ result = eightbyte_get_byte(data, 0, false);
//result = 0x0
- result = nth_byte(data, 4);
+ result = eightbyte_get_byte(data, 4, false);
//result = 0xF3
-## 8 Byte Bitfield Encoding
+ result = eightbyte_get_nibble(data, 10, false);
+ //result = 0x4;
+
+### 8 Byte Encoding
uint64_t data = 0;
fail_unless(set_bit_field(&data, 1, 0, 1));
uint64_t result = get_bit_field(data, 0, 1, false);
ck_assert_int_eq(result, 0x1);
-TODO setting bit fields is just copying
-
-## CAN Signal Encoding
+### CAN Signal Encoding
The library supports encoding floating point CAN signals as well as booleans
into a uint64_t payload.
payload = bitfield_encode_bool(true, 1, 3);
// payload == 0x1000000000000000
-## CAN Signal Decoding
+### CAN Signal Decoding
The library supports parsing floating point CAN signals as well as booleans.
## Testing
-The library includes a test suite that uses the `check` C unit test library.
+The library includes a test suite that uses the `check` C unit test library. It
+requires the unit testing library `check`.
$ make test