alif/mpconfigport: Enable os.urandom().

Uses the SE services to provide random numbers.

Signed-off-by: Damien George <damien@micropython.org>

Author: dpgeorge

ports/alif/modos.c

@@ -0,0 +1,49 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2024 OpenMV LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/runtime.h"
+#include "se_services.h"
+
+#if MICROPY_PY_OS_URANDOM
+static mp_obj_t mp_os_urandom(mp_obj_t num) {
+    mp_int_t n = mp_obj_get_int(num);
+    vstr_t vstr;
+    vstr_init_len(&vstr, n);
+    uint64_t rnd = 0;
+    size_t rnd_bits = 0;
+    for (int i = 0; i < n; i++) {
+        if (rnd_bits == 0) {
+            rnd = se_services_rand64();
+            rnd_bits = 64;
+        }
+        vstr.buf[i] = rnd;
+        rnd >>= 8;
+        rnd_bits -= 8;
+    }
+    return mp_obj_new_bytes_from_vstr(&vstr);
+}
+static MP_DEFINE_CONST_FUN_OBJ_1(mp_os_urandom_obj, mp_os_urandom);
+#endif

ports/alif/mpconfigport.h

@@ -87,10 +87,12 @@
 
 // Extended modules
 #define MICROPY_EPOCH_IS_1970                   (1)
+#define MICROPY_PY_OS_INCLUDEFILE               "ports/alif/modos.c"
 #define MICROPY_PY_OS_DUPTERM                   (1)
 #define MICROPY_PY_OS_SEP                       (1)
 #define MICROPY_PY_OS_SYNC                      (1)
 #define MICROPY_PY_OS_UNAME                     (1)
+#define MICROPY_PY_OS_URANDOM                   (1)
 #define MICROPY_PY_TIME                         (1)
 #define MICROPY_PY_MACHINE                      (1)
 #define MICROPY_PY_MACHINE_INCLUDEFILE          "ports/alif/modmachine.c"