Use less memory in fix_negative()
diff --git a/library/ecp.c b/library/ecp.c
index 995f956..64d4e03 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -1736,12 +1736,20 @@
/*
* Helpers for the main 'loop'
+ * (see fix_negative for the motivation of C)
*/
#define INIT( b ) \
int ret; \
signed char c = 0, cc; \
uint32_t cur; \
size_t i = 0, bits = b; \
+ mpi C; \
+ t_uint Cp[ b / 8 / sizeof( t_uint) + 1 ]; \
+ \
+ C.s = 1; \
+ C.n = b / 8 / sizeof( t_uint) + 1; \
+ C.p = Cp; \
+ memset( Cp, 0, C.n * sizeof( t_uint ) ); \
\
MPI_CHK( mpi_grow( N, b * 2 / 8 / sizeof( t_uint ) ) ); \
LOAD32;
@@ -1758,32 +1766,28 @@
STORE32; i++; \
cur = c > 0 ? c : 0; STORE32; \
cur = 0; while( ++i < MAX32 ) { STORE32; } \
- if( c < 0 ) fix_negative( N, c, bits );
+ if( c < 0 ) fix_negative( N, c, &C, bits );
/*
* If the result is negative, we get it in the form
* c * 2^(bits + 32) + N, with c negative and N positive shorter than 'bits'
*/
-static inline int fix_negative( mpi *N, signed char c, size_t bits )
+static inline int fix_negative( mpi *N, signed char c, mpi *C, size_t bits )
{
int ret;
- mpi C;
- t_uint Cp[ 384 / 8 / sizeof( t_uint) + 1 ];
/* C = - c * 2^(bits + 32) */
- C.s = 1;
- C.n = bits / 8 / sizeof( t_uint ) + 1;
- C.p = Cp;
- memset( Cp, 0, C.n * sizeof( t_uint ) );
-#if defined(POLARSSL_HAVE_INT64)
+#if !defined(POLARSSL_HAVE_INT64)
+ ((void) bits);
+#else
if( bits == 224 )
- Cp[ C.n - 1 ] = ((t_uint) -c) << 32;
+ C->p[ C->n - 1 ] = ((t_uint) -c) << 32;
else
#endif
- Cp[ C.n - 1 ] = (t_uint) -c;
+ C->p[ C->n - 1 ] = (t_uint) -c;
/* N = - ( C - N ) */
- MPI_CHK( mpi_sub_abs( N, &C, N ) );
+ MPI_CHK( mpi_sub_abs( N, C, N ) );
N->s = -1;
cleanup:
