Support different types in the parameter store

The test framework stores size_t and int32_t values in the parameter store
by converting them all to int. This is ok in practice, since we assume int
covers int32_t and we don't have test data larger than 2GB. But it's
confusing and error-prone. So make the parameter store a union, which allows
size_t values not to be potentially truncated and makes the code a little
clearer.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/scripts/generate_test_code.py b/tests/scripts/generate_test_code.py
index 6b5f11b..54c7e3a 100755
--- a/tests/scripts/generate_test_code.py
+++ b/tests/scripts/generate_test_code.py
@@ -471,7 +471,7 @@
             continue
         if re.search(INT_CHECK_REGEX, arg.strip()):
             args.append('int')
-            args_dispatch.append('*( (int *) params[%d] )' % arg_idx)
+            args_dispatch.append('((mbedtls_test_argument_t*)params[%d])->s32' % arg_idx)
         elif re.search(CHAR_CHECK_REGEX, arg.strip()):
             args.append('char*')
             args_dispatch.append('(char *) params[%d]' % arg_idx)
@@ -479,7 +479,7 @@
             args.append('hex')
             # create a structure
             pointer_initializer = '(uint8_t *) params[%d]' % arg_idx
-            len_initializer = '*( (uint32_t *) params[%d] )' % (arg_idx+1)
+            len_initializer = '((mbedtls_test_argument_t*)params[%d])->len' % (arg_idx+1)
             local_vars += """    data_t data%d = {%s, %s};
 """ % (arg_idx, pointer_initializer, len_initializer)