diff options
Diffstat (limited to 'lib/mpi')
| -rw-r--r-- | lib/mpi/mpicoder.c | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c index 95c52a95259e..c20ef27ad876 100644 --- a/lib/mpi/mpicoder.c +++ b/lib/mpi/mpicoder.c @@ -319,3 +319,199 @@ int mpi_set_buffer(MPI a, const void *xbuffer, unsigned nbytes, int sign) return 0; } EXPORT_SYMBOL_GPL(mpi_set_buffer); + +/** + * mpi_write_to_sgl() - Funnction exports MPI to an sgl (msb first) + * + * This function works in the same way as the mpi_read_buffer, but it + * takes an sgl instead of u8 * buf. + * + * @a: a multi precision integer + * @sgl: scatterlist to write to. Needs to be at least + * mpi_get_size(a) long. + * @nbytes: in/out param - it has the be set to the maximum number of + * bytes that can be written to sgl. This has to be at least + * the size of the integer a. On return it receives the actual + * length of the data written. + * @sign: if not NULL, it will be set to the sign of a. + * + * Return: 0 on success or error code in case of error + */ +int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned *nbytes, + int *sign) +{ + u8 *p, *p2; + mpi_limb_t alimb, alimb2; + unsigned int n = mpi_get_size(a); + int i, x, y = 0, lzeros = 0, buf_len; + + if (!nbytes || *nbytes < n) + return -EINVAL; + + if (sign) + *sign = a->sign; + + p = (void *)&a->d[a->nlimbs] - 1; + + for (i = a->nlimbs * sizeof(alimb) - 1; i >= 0; i--, p--) { + if (!*p) + lzeros++; + else + break; + } + + *nbytes = n - lzeros; + buf_len = sgl->length; + p2 = sg_virt(sgl); + + for (i = a->nlimbs - 1; i >= 0; i--) { + alimb = a->d[i]; + p = (u8 *)&alimb2; +#if BYTES_PER_MPI_LIMB == 4 + *p++ = alimb >> 24; + *p++ = alimb >> 16; + *p++ = alimb >> 8; + *p++ = alimb; +#elif BYTES_PER_MPI_LIMB == 8 + *p++ = alimb >> 56; + *p++ = alimb >> 48; + *p++ = alimb >> 40; + *p++ = alimb >> 32; + *p++ = alimb >> 24; + *p++ = alimb >> 16; + *p++ = alimb >> 8; + *p++ = alimb; +#else +#error please implement for this limb size. +#endif + if (lzeros > 0) { + if (lzeros >= sizeof(alimb)) { + p -= sizeof(alimb); + continue; + } else { + mpi_limb_t *limb1 = (void *)p - sizeof(alimb); + mpi_limb_t *limb2 = (void *)p - sizeof(alimb) + + lzeros; + *limb1 = *limb2; + p -= lzeros; + y = lzeros; + } + lzeros -= sizeof(alimb); + } + + p = p - (sizeof(alimb) - y); + + for (x = 0; x < sizeof(alimb) - y; x++) { + if (!buf_len) { + sgl = sg_next(sgl); + if (!sgl) + return -EINVAL; + buf_len = sgl->length; + p2 = sg_virt(sgl); + } + *p2++ = *p++; + buf_len--; + } + y = 0; + } + return 0; +} +EXPORT_SYMBOL_GPL(mpi_write_to_sgl); + +/* + * mpi_read_raw_from_sgl() - Function allocates an MPI and populates it with + * data from the sgl + * + * This function works in the same way as the mpi_read_raw_data, but it + * takes an sgl instead of void * buffer. i.e. it allocates + * a new MPI and reads the content of the sgl to the MPI. + * + * @sgl: scatterlist to read from + * @len: number of bytes to read + * + * Return: Pointer to a new MPI or NULL on error + */ +MPI mpi_read_raw_from_sgl(struct scatterlist *sgl, unsigned int len) +{ + struct scatterlist *sg; + int x, i, j, z, lzeros, ents; + unsigned int nbits, nlimbs, nbytes; + mpi_limb_t a; + MPI val = NULL; + + lzeros = 0; + ents = sg_nents(sgl); + + for_each_sg(sgl, sg, ents, i) { + const u8 *buff = sg_virt(sg); + int len = sg->length; + + while (len-- && !*buff++) + lzeros++; + + if (len && *buff) + break; + + ents--; + lzeros = 0; + } + + sgl = sg; + + if (!ents) + nbytes = 0; + else + nbytes = len - lzeros; + + 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(*(u8 *)(sg_virt(sgl) + lzeros)); + else + nbits = 0; + + nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB); + val = mpi_alloc(nlimbs); + if (!val) + return NULL; + + val->nbits = nbits; + val->sign = 0; + val->nlimbs = nlimbs; + + if (nbytes == 0) + return val; + + j = nlimbs - 1; + a = 0; + z = 0; + x = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB; + x %= BYTES_PER_MPI_LIMB; + + for_each_sg(sgl, sg, ents, i) { + const u8 *buffer = sg_virt(sg) + lzeros; + int len = sg->length - lzeros; + int buf_shift = x; + + if (sg_is_last(sg) && (len % BYTES_PER_MPI_LIMB)) + len += BYTES_PER_MPI_LIMB - (len % BYTES_PER_MPI_LIMB); + + for (; x < len + buf_shift; x++) { + a <<= 8; + a |= *buffer++; + if (((z + x + 1) % BYTES_PER_MPI_LIMB) == 0) { + val->d[j--] = a; + a = 0; + } + } + z += x; + x = 0; + lzeros = 0; + } + return val; +} +EXPORT_SYMBOL_GPL(mpi_read_raw_from_sgl); |