[PATCH v3 07/14] lib/mpi: mpi_read_buffer(): replace open coded endian conversion

[Nicolai Stange]

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 <nicsta...@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)
-- 
2.7.4

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