[PATCH v2 07/14] lib/mpi: mpi_read_buffer(): replace open coded endian conversion

Nicolai Stange
2016-03-20T12:33:59Z

Currently, the endian conversion from CPU order to BE is open coded in
mpi_read_buffer().

Replace this by the centrally provided cpu_to_be*() macros.
Copy from the temporary storage on stack to the destination buffer
by means of memcpy().

Signed-off-by: Nicolai Stange <nicstange@gmail.com>
---
lib/mpi/mpicoder.c | 27 ++++++++++++---------------
1 file changed, 12 insertions(+), 15 deletions(-)

diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c
index 2fd8d41..a999ee1 100644
--- a/lib/mpi/mpicoder.c
+++ b/lib/mpi/mpicoder.c
@@ -21,6 +21,7 @@
#include <linux/bitops.h>
#include <linux/count_zeros.h>
#include <linux/byteorder/generic.h>
+#include <linux/string.h>
#include "mpi-internal.h"

#define MAX_EXTERN_MPI_BITS 16384
@@ -164,7 +165,13 @@ int mpi_read_buffer(MPI a, uint8_t *buf, unsigned buf_len, unsigned *nbytes,
int *sign)
{
uint8_t *p;
- mpi_limb_t alimb;
+#if BYTES_PER_MPI_LIMB == 4
+ __be32 alimb;
+#elif BYTES_PER_MPI_LIMB == 8
+ __be64 alimb;
+#else
+#error please implement for this limb size.
+#endif
unsigned int n = mpi_get_size(a);
int i, lzeros;

@@ -187,25 +194,15 @@ int mpi_read_buffer(MPI a, uint8_t *buf, unsigned buf_len, unsigned *nbytes,
for (i = a->nlimbs - 1 - lzeros / BYTES_PER_MPI_LIMB,
lzeros %= BYTES_PER_MPI_LIMB;
i >= 0; i--) {
- alimb = a->d[i];
#if BYTES_PER_MPI_LIMB == 4
- *p++ = alimb >> 24;
- *p++ = alimb >> 16;
- *p++ = alimb >> 8;
- *p++ = alimb;
+ alimb = cpu_to_be32(a->d[i]);
#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;
+ alimb = cpu_to_be64(a->d[i]);
#else
#error please implement for this limb size.
#endif
-
+ memcpy(p, &alimb, BYTES_PER_MPI_LIMB);
+ p += BYTES_PER_MPI_LIMB;
if (lzeros > 0) {
mpi_limb_t *limb1 = (void *)p - sizeof(alimb);
mpi_limb_t *limb2 = (void *)p - sizeof(alimb)
--
2.7.3