diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/mpi/mpicoder.c | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c index f0fa65995800..3962b7f7fe3f 100644 --- a/lib/mpi/mpicoder.c +++ b/lib/mpi/mpicoder.c @@ -18,10 +18,65 @@ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA */ +#include <linux/bitops.h> +#include <asm-generic/bitops/count_zeros.h> #include "mpi-internal.h" #define MAX_EXTERN_MPI_BITS 16384 +/** + * mpi_read_raw_data - Read a raw byte stream as a positive integer + * @xbuffer: The data to read + * @nbytes: The amount of data to read + */ +MPI mpi_read_raw_data(const void *xbuffer, size_t nbytes) +{ + const uint8_t *buffer = xbuffer; + int i, j; + unsigned nbits, nlimbs; + mpi_limb_t a; + MPI val = NULL; + + while (nbytes >= 0 && buffer[0] == 0) { + buffer++; + nbytes--; + } + + nbits = nbytes * 8; + if (nbits > MAX_EXTERN_MPI_BITS) { + pr_info("MPI: mpi too large (%u bits)\n", nbits); + return NULL; + } + if (nbytes > 0) + nbits -= count_leading_zeros(buffer[0]); + else + nbits = 0; + + nlimbs = (nbytes + BYTES_PER_MPI_LIMB - 1) / BYTES_PER_MPI_LIMB; + val = mpi_alloc(nlimbs); + if (!val) + return NULL; + val->nbits = nbits; + val->sign = 0; + val->nlimbs = nlimbs; + + if (nbytes > 0) { + i = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB; + i %= BYTES_PER_MPI_LIMB; + for (j = nlimbs; j > 0; j--) { + a = 0; + for (; i < BYTES_PER_MPI_LIMB; i++) { + a <<= 8; + a |= *buffer++; + } + i = 0; + val->d[j - 1] = a; + } + } + return val; +} +EXPORT_SYMBOL_GPL(mpi_read_raw_data); + MPI mpi_read_from_buffer(const void *xbuffer, unsigned *ret_nread) { const uint8_t *buffer = xbuffer; |