Add mbedtls_ct_bool_if and mbedtls_ct_bool_if_else_0
Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/library/constant_time_impl.h b/library/constant_time_impl.h
index 98a5663..513f146 100644
--- a/library/constant_time_impl.h
+++ b/library/constant_time_impl.h
@@ -350,6 +350,14 @@
return (unsigned) mbedtls_ct_if(condition, (mbedtls_ct_uint_t) if1, (mbedtls_ct_uint_t) if0);
}
+static inline mbedtls_ct_condition_t mbedtls_ct_bool_if(mbedtls_ct_condition_t condition,
+ mbedtls_ct_condition_t if1,
+ mbedtls_ct_condition_t if0)
+{
+ return (mbedtls_ct_condition_t) mbedtls_ct_if(condition, (mbedtls_ct_uint_t) if1,
+ (mbedtls_ct_uint_t) if0);
+}
+
#if defined(MBEDTLS_BIGNUM_C)
static inline mbedtls_mpi_uint mbedtls_ct_mpi_uint_if(mbedtls_ct_condition_t condition,
@@ -373,6 +381,12 @@
return (unsigned) (condition & if1);
}
+static inline mbedtls_ct_condition_t mbedtls_ct_bool_if_else_0(mbedtls_ct_condition_t condition,
+ mbedtls_ct_condition_t if1)
+{
+ return (mbedtls_ct_condition_t) (condition & if1);
+}
+
#if defined(MBEDTLS_BIGNUM_C)
static inline mbedtls_mpi_uint mbedtls_ct_mpi_uint_if_else_0(mbedtls_ct_condition_t condition,
diff --git a/library/constant_time_internal.h b/library/constant_time_internal.h
index 50c08fa..d3d8945 100644
--- a/library/constant_time_internal.h
+++ b/library/constant_time_internal.h
@@ -291,6 +291,22 @@
unsigned if1,
unsigned if0);
+/** Choose between two mbedtls_ct_condition_t values.
+ *
+ * Functionally equivalent to:
+ *
+ * condition ? if1 : if0.
+ *
+ * \param condition Condition to test.
+ * \param if1 Value to use if \p condition == MBEDTLS_CT_TRUE.
+ * \param if0 Value to use if \p condition == MBEDTLS_CT_FALSE.
+ *
+ * \return \c if1 if \p condition == MBEDTLS_CT_TRUE, otherwise \c if0.
+ */
+static inline mbedtls_ct_condition_t mbedtls_ct_bool_if(mbedtls_ct_condition_t condition,
+ mbedtls_ct_condition_t if1,
+ mbedtls_ct_condition_t if0);
+
#if defined(MBEDTLS_BIGNUM_C)
/** Choose between two mbedtls_mpi_uint values.
@@ -327,6 +343,23 @@
*/
static inline unsigned mbedtls_ct_uint_if_else_0(mbedtls_ct_condition_t condition, unsigned if1);
+/** Choose between an mbedtls_ct_condition_t and 0.
+ *
+ * Functionally equivalent to:
+ *
+ * condition ? if1 : 0.
+ *
+ * Functionally equivalent to mbedtls_ct_bool_if(condition, if1, 0) but
+ * results in smaller code size.
+ *
+ * \param condition Condition to test.
+ * \param if1 Value to use if \p condition == MBEDTLS_CT_TRUE.
+ *
+ * \return \c if1 if \p condition == MBEDTLS_CT_TRUE, otherwise 0.
+ */
+static inline mbedtls_ct_condition_t mbedtls_ct_bool_if_else_0(mbedtls_ct_condition_t condition,
+ mbedtls_ct_condition_t if1);
+
/** Choose between a size_t value and 0.
*
* Functionally equivalent to: