diff options
author | Christopher Peplin <chris.peplin@rhubarbtech.com> | 2014-01-02 17:56:20 -0500 |
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committer | Christopher Peplin <chris.peplin@rhubarbtech.com> | 2014-01-02 17:56:45 -0500 |
commit | 31caa9c77dbfc438a104fbcab6db5165528c0f89 (patch) | |
tree | 62f4d0741eb47dc09db717f6cc40432163cb5b7d /src/bitfield/8byte.h | |
parent | 4af52c415f1668fbd168da74d0aca903c592463f (diff) |
Clarify when you need to specify endianness.
Diffstat (limited to 'src/bitfield/8byte.h')
-rw-r--r-- | src/bitfield/8byte.h | 24 |
1 files changed, 7 insertions, 17 deletions
diff --git a/src/bitfield/8byte.h b/src/bitfield/8byte.h index e4773a51..0abc1f07 100644 --- a/src/bitfield/8byte.h +++ b/src/bitfield/8byte.h @@ -8,25 +8,15 @@ extern "C" { #endif -// TODO using uint64_t everywhere for CAN message payload is kind of cute, but -// in actuality a CAN message may have a smaller payload, and it makes all of -// these functions not applicable to other data sizes. It's also fairly -// inefficient on 32-bit platforms. how much work is it to switch vi-firmware -// to using uint8_t*? - /* Public: Reads a subset of bits into a uint64_t. * * source - the bytes in question. * offset - the starting index of the bit field (beginning from 0). * bit_count - the width of the bit field to extract. - * big_endian - if the data passed in is little endian, set this to false and it + * data_is_big_endian - if the data passed in is little endian, set this to false and it * will be flipped before grabbing the bit field. * - * Bit fields are positioned according to big-endian bit layout, but inside the - * bit field, values are represented as little-endian. Therefore, to get the bit - * field, we swap the overall byte order if big_endian == false and - * use the value we find in the field (assuming the embedded platform is little - * endian). + * Bit fields are positioned according to big-endian bit layout. * * For example, the bit layout of the value "42" (i.e. 00101010 set at position * 14 with length 6 is: @@ -47,32 +37,32 @@ extern "C" { * Returns the value of the requested bit field, right aligned in a uint64_t. */ uint64_t get_bit_field(uint64_t source, const uint16_t offset, - const uint16_t bit_count, const bool big_endian); + const uint16_t bit_count, const bool data_is_big_endian); /* Public: Return a single nibble from the payload, with range checking. * * source - the source payload. * nibble_index - the index of the nibble to retreive. The leftmost nibble is * index 0. - * big_endian - if the data passed in is little endian, set this to false and it + * data_is_big_endian - if the data passed in is little endian, set this to false and it * will be flipped before grabbing the bit field. * * Returns the retreived nibble, right aligned in a uint8_t. */ uint8_t eightbyte_get_nibble(const uint64_t source, const uint8_t nibble_index, - const bool big_endian); + const bool data_is_big_endian); /* Public: Return a single byte from the payload, with range checking. * * source - the source byte array. * byte_index - the index of the byte to retreive. The leftmost byte is index 0. - * big_endian - if the data passed in is little endian, set this to false and it + * data_is_big_endian - if the data passed in is little endian, set this to false and it * will be flipped before grabbing the bit field. * * Returns the retreived byte. */ uint8_t eightbyte_get_byte(const uint64_t source, const uint8_t byte_index, - const bool big_endian); + const bool data_is_big_endian); /* Public: Set the bit field in the given data array to the new value. * |