Move asn1_skip_integer to the asn1_helpers module

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/suites/test_suite_psa_crypto.function b/tests/suites/test_suite_psa_crypto.function
index 37cc551..f0b8647 100644
--- a/tests/suites/test_suite_psa_crypto.function
+++ b/tests/suites/test_suite_psa_crypto.function
@@ -12,6 +12,7 @@
 #include "psa/crypto.h"
 #include "psa_crypto_slot_management.h"
 
+#include "test/asn1_helpers.h"
 #include "test/psa_crypto_helpers.h"
 
 /** An invalid export length that will never be set by psa_export_key(). */
@@ -818,50 +819,6 @@
     return( ok );
 }
 
-int asn1_skip_integer( unsigned char **p, const unsigned char *end,
-                       size_t min_bits, size_t max_bits,
-                       int must_be_odd )
-{
-    size_t len;
-    size_t actual_bits;
-    unsigned char msb;
-    TEST_EQUAL( mbedtls_asn1_get_tag( p, end, &len,
-                                      MBEDTLS_ASN1_INTEGER ),
-                0 );
-
-    /* Check if the retrieved length doesn't extend the actual buffer's size.
-     * It is assumed here, that end >= p, which validates casting to size_t. */
-    TEST_ASSERT( len <= (size_t)( end - *p) );
-
-    /* Tolerate a slight departure from DER encoding:
-     * - 0 may be represented by an empty string or a 1-byte string.
-     * - The sign bit may be used as a value bit. */
-    if( ( len == 1 && ( *p )[0] == 0 ) ||
-        ( len > 1 && ( *p )[0] == 0 && ( ( *p )[1] & 0x80 ) != 0 ) )
-    {
-        ++( *p );
-        --len;
-    }
-    if( min_bits == 0 && len == 0 )
-        return( 1 );
-    msb = ( *p )[0];
-    TEST_ASSERT( msb != 0 );
-    actual_bits = 8 * ( len - 1 );
-    while( msb != 0 )
-    {
-        msb >>= 1;
-        ++actual_bits;
-    }
-    TEST_ASSERT( actual_bits >= min_bits );
-    TEST_ASSERT( actual_bits <= max_bits );
-    if( must_be_odd )
-        TEST_ASSERT( ( ( *p )[len-1] & 1 ) != 0 );
-    *p += len;
-    return( 1 );
-exit:
-    return( 0 );
-}
-
 int mbedtls_test_psa_exported_key_sanity_check(
     psa_key_type_t type, size_t bits,
     uint8_t *exported, size_t exported_length )
@@ -913,25 +870,25 @@
                                           MBEDTLS_ASN1_SEQUENCE |
                                           MBEDTLS_ASN1_CONSTRUCTED ), 0 );
         TEST_EQUAL( p + len, end );
-        if( ! asn1_skip_integer( &p, end, 0, 0, 0 ) )
+        if( ! mbedtls_test_asn1_skip_integer( &p, end, 0, 0, 0 ) )
             goto exit;
-        if( ! asn1_skip_integer( &p, end, bits, bits, 1 ) )
+        if( ! mbedtls_test_asn1_skip_integer( &p, end, bits, bits, 1 ) )
             goto exit;
-        if( ! asn1_skip_integer( &p, end, 2, bits, 1 ) )
+        if( ! mbedtls_test_asn1_skip_integer( &p, end, 2, bits, 1 ) )
             goto exit;
         /* Require d to be at least half the size of n. */
-        if( ! asn1_skip_integer( &p, end, bits / 2, bits, 1 ) )
+        if( ! mbedtls_test_asn1_skip_integer( &p, end, bits / 2, bits, 1 ) )
             goto exit;
         /* Require p and q to be at most half the size of n, rounded up. */
-        if( ! asn1_skip_integer( &p, end, bits / 2, bits / 2 + 1, 1 ) )
+        if( ! mbedtls_test_asn1_skip_integer( &p, end, bits / 2, bits / 2 + 1, 1 ) )
             goto exit;
-        if( ! asn1_skip_integer( &p, end, bits / 2, bits / 2 + 1, 1 ) )
+        if( ! mbedtls_test_asn1_skip_integer( &p, end, bits / 2, bits / 2 + 1, 1 ) )
             goto exit;
-        if( ! asn1_skip_integer( &p, end, 1, bits / 2 + 1, 0 ) )
+        if( ! mbedtls_test_asn1_skip_integer( &p, end, 1, bits / 2 + 1, 0 ) )
             goto exit;
-        if( ! asn1_skip_integer( &p, end, 1, bits / 2 + 1, 0 ) )
+        if( ! mbedtls_test_asn1_skip_integer( &p, end, 1, bits / 2 + 1, 0 ) )
             goto exit;
-        if( ! asn1_skip_integer( &p, end, 1, bits / 2 + 1, 0 ) )
+        if( ! mbedtls_test_asn1_skip_integer( &p, end, 1, bits / 2 + 1, 0 ) )
             goto exit;
         TEST_EQUAL( p, end );
     }
@@ -964,9 +921,9 @@
                                               MBEDTLS_ASN1_CONSTRUCTED ),
                         0 );
             TEST_EQUAL( p + len, end );
-            if( ! asn1_skip_integer( &p, end, bits, bits, 1 ) )
+            if( ! mbedtls_test_asn1_skip_integer( &p, end, bits, bits, 1 ) )
                 goto exit;
-            if( ! asn1_skip_integer( &p, end, 2, bits, 1 ) )
+            if( ! mbedtls_test_asn1_skip_integer( &p, end, 2, bits, 1 ) )
                 goto exit;
             TEST_EQUAL( p, end );
         }
@@ -5632,7 +5589,7 @@
         TEST_EQUAL( 0, mbedtls_asn1_get_tag( &p, end, &len,
                                              MBEDTLS_ASN1_SEQUENCE |
                                              MBEDTLS_ASN1_CONSTRUCTED ) );
-        TEST_ASSERT( asn1_skip_integer( &p, end, bits, bits, 1 ) );
+        TEST_ASSERT( mbedtls_test_asn1_skip_integer( &p, end, bits, bits, 1 ) );
         TEST_EQUAL( 0, mbedtls_asn1_get_tag( &p, end, &len,
                                              MBEDTLS_ASN1_INTEGER ) );
         if( len >= 1 && p[0] == 0 )