diff options
| author | Shawn Nematbakhsh <shawnn@chromium.org> | 2016-03-15 16:00:09 -0700 |
|---|---|---|
| committer | chrome-bot <chrome-bot@chromium.org> | 2016-03-18 22:16:53 -0700 |
| commit | 952b2a54e12bfbf6635a5eb225ad777814ca9c92 (patch) | |
| tree | 36aeb0608546450ec382f5370d04d1142dc518ba | |
| parent | f06443e2f7020b98dbb7145bedc930327b8c25dd (diff) | |
| download | chrome-ec-952b2a54e12bfbf6635a5eb225ad777814ca9c92.tar.gz | |
crc8: Support crc calculation across non-contiguous data
Building a single buffer for crc calculation is often inefficient, so
add a new function that calculates crc8 from an existing crc8.
BUG=chromium:576911
BRANCH=None
TEST=Manual on sentry with subsequent commit. Verify that smbus
communication with battery is functional.
Change-Id: I05ffedb81ffcf0c126acda5f6212b3147b1580a1
Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/333786
Commit-Ready: Shawn N <shawnn@chromium.org>
Tested-by: Shawn N <shawnn@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
| -rw-r--r-- | common/crc8.c | 9 | ||||
| -rw-r--r-- | include/crc8.h | 14 |
2 files changed, 20 insertions, 3 deletions
diff --git a/common/crc8.c b/common/crc8.c index b752698d14..ca32d5a19c 100644 --- a/common/crc8.c +++ b/common/crc8.c @@ -5,9 +5,14 @@ #include "common.h" #include "crc8.h" -uint8_t crc8(const uint8_t *data, int len) +inline uint8_t crc8(const uint8_t *data, int len) { - unsigned crc = 0; + return crc8_arg(data, len, 0); +} + +uint8_t crc8_arg(const uint8_t *data, int len, uint8_t previous_crc) +{ + unsigned crc = previous_crc << 8; int i, j; for (j = len; j; j--, data++) { diff --git a/include/crc8.h b/include/crc8.h index de0dc196f9..c98d65ce4d 100644 --- a/include/crc8.h +++ b/include/crc8.h @@ -13,9 +13,21 @@ * algorithm would be faster, but for only a few bytes it isn't worth the code * size. * @param data uint8_t *, input, a pointer to input data - * @param len int, input, size of iput data in byte + * @param len int, input, size of input data in bytes * @return the crc-8 of the input data. */ uint8_t crc8(const uint8_t *data, int len); +/** + * crc8_arg + * Return CRC-8 of the data, based upon pre-calculated partial CRC of previous + * data. + * @param data uint8_t *, input, a pointer to input data + * @param len int, input, size of input data in bytes + * @param previous_crc uint8_t, input, pre-calculated CRC of previous data. + * Seed with zero for a new calculation (or use the result of crc8()). + * @return the crc-8 of the input data. + */ +uint8_t crc8_arg(const uint8_t *data, int len, uint8_t previous_crc); + #endif /* __CROS_EC_CRC8_H */ |