interpreters/python: Add Python's port to NuttX

This is the NuttX's port of Python (cpython)!

Initial support of Python includes building the Python's static
library and the `python` (Programs/python.c) application. Python's
modules are stored in `pyc` (byte-code file) and loaded as needed
from flash.

interpreters/python/mount_modules.c

@@ -0,0 +1,132 @@
+/****************************************************************************
+ * apps/interpreters/python/mount_modules.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <sys/boardctl.h>
+#include <inttypes.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <fcntl.h>
+#include <dirent.h>
+#include <errno.h>
+
+#include <nuttx/drivers/ramdisk.h>
+
+#include "romfs_cpython_modules.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* Configuration settings */
+
+#ifndef CONFIG_CPYTHON_ROMFS_RAMDEVNO
+#  define CONFIG_CPYTHON_ROMFS_RAMDEVNO 1
+#endif
+
+#ifndef CONFIG_CPYTHON_ROMFS_SECTORSIZE
+#  define CONFIG_CPYTHON_ROMFS_SECTORSIZE 64
+#endif
+
+#ifndef CONFIG_CPYTHON_ROMFS_MOUNTPOINT
+#  define CONFIG_CPYTHON_ROMFS_MOUNTPOINT "/usr/local/lib/"
+#endif
+
+#ifdef CONFIG_DISABLE_MOUNTPOINT
+#  error "Mountpoint support is disabled"
+#endif
+
+#ifndef CONFIG_FS_ROMFS
+#  error "ROMFS support not enabled"
+#endif
+
+#define NSECTORS(b)        (((b)+CONFIG_CPYTHON_ROMFS_SECTORSIZE-1)/CONFIG_CPYTHON_ROMFS_SECTORSIZE)
+#define STR_RAMDEVNO(m)    #m
+#define MKMOUNT_DEVNAME(m) "/dev/ram" STR_RAMDEVNO(m)
+#define MOUNT_DEVNAME      MKMOUNT_DEVNAME(CONFIG_CPYTHON_ROMFS_RAMDEVNO)
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: mount_modules
+ ****************************************************************************/
+
+int main(int argc, FAR char *argv[])
+{
+  int ret;
+  struct boardioc_romdisk_s desc;
+
+  /* Create a RAM disk for the test */
+
+  desc.minor    = CONFIG_CPYTHON_ROMFS_RAMDEVNO;            /* Minor device number of the ROM disk. */
+  desc.nsectors = NSECTORS(romfs_cpython_modules_img_len);  /* The number of sectors in the ROM disk */
+  desc.sectsize = CONFIG_CPYTHON_ROMFS_SECTORSIZE;          /* The size of one sector in bytes */
+  desc.image    = (FAR uint8_t *)romfs_cpython_modules_img; /* File system image */
+
+  ret = boardctl(BOARDIOC_ROMDISK, (uintptr_t)&desc);
+
+  if (ret < 0)
+    {
+      printf("ERROR: Failed to create RAM disk: %s\n", strerror(errno));
+      return 1;
+    }
+
+  /* Mount the test file system */
+
+  printf("Mounting ROMFS filesystem at target=%s with source=%s\n",
+         CONFIG_CPYTHON_ROMFS_MOUNTPOINT, MOUNT_DEVNAME);
+
+  ret = mount(MOUNT_DEVNAME, CONFIG_CPYTHON_ROMFS_MOUNTPOINT, "romfs",
+              MS_RDONLY, NULL);
+  if (ret < 0)
+    {
+      printf("ERROR: Mount failed: %s\n", strerror(errno));
+      return 1;
+    }
+
+  return 0;
+}