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[crypto] Profile the various stages of modular multiplication
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Signed-off-by: Michael Brown <mcb30@ipxe.org>
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mcb30 committed Aug 17, 2019
1 parent 131635e commit 0cc12f0
Showing 1 changed file with 29 additions and 0 deletions.
29 changes: 29 additions & 0 deletions src/crypto/bigint.c
Expand Up @@ -26,13 +26,30 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <stdint.h>
#include <string.h>
#include <assert.h>
#include <ipxe/profile.h>
#include <ipxe/bigint.h>

/** @file
*
* Big integer support
*/

/** Modular multiplication overall profiler */
static struct profiler bigint_mod_multiply_profiler __profiler =
{ .name = "bigint_mod_multiply" };

/** Modular multiplication multiply step profiler */
static struct profiler bigint_mod_multiply_multiply_profiler __profiler =
{ .name = "bigint_mod_multiply.multiply" };

/** Modular multiplication rescale step profiler */
static struct profiler bigint_mod_multiply_rescale_profiler __profiler =
{ .name = "bigint_mod_multiply.rescale" };

/** Modular multiplication subtract step profiler */
static struct profiler bigint_mod_multiply_subtract_profiler __profiler =
{ .name = "bigint_mod_multiply.subtract" };

/**
* Perform modular multiplication of big integers
*
Expand Down Expand Up @@ -63,31 +80,43 @@ void bigint_mod_multiply_raw ( const bigint_element_t *multiplicand0,
int rotation;
int i;

/* Start profiling */
profile_start ( &bigint_mod_multiply_profiler );

/* Sanity check */
assert ( sizeof ( *temp ) == bigint_mod_multiply_tmp_len ( modulus ) );

/* Perform multiplication */
profile_start ( &bigint_mod_multiply_multiply_profiler );
bigint_multiply ( multiplicand, multiplier, &temp->result );
profile_stop ( &bigint_mod_multiply_multiply_profiler );

/* Rescale modulus to match result */
profile_start ( &bigint_mod_multiply_rescale_profiler );
bigint_grow ( modulus, &temp->modulus );
rotation = ( bigint_max_set_bit ( &temp->result ) -
bigint_max_set_bit ( &temp->modulus ) );
for ( i = 0 ; i < rotation ; i++ )
bigint_rol ( &temp->modulus );
profile_stop ( &bigint_mod_multiply_rescale_profiler );

/* Subtract multiples of modulus */
profile_start ( &bigint_mod_multiply_subtract_profiler );
for ( i = 0 ; i <= rotation ; i++ ) {
if ( bigint_is_geq ( &temp->result, &temp->modulus ) )
bigint_subtract ( &temp->modulus, &temp->result );
bigint_ror ( &temp->modulus );
}
profile_stop ( &bigint_mod_multiply_subtract_profiler );

/* Resize result */
bigint_shrink ( &temp->result, result );

/* Sanity check */
assert ( bigint_is_geq ( modulus, result ) );

/* Stop profiling */
profile_stop ( &bigint_mod_multiply_profiler );
}

/**
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