zephyr: Implement the help() function.

The boot issue text mentions a help() function and encourages
the user to run it. It is very disconcerting to find that the
function does not exist...

Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>

zephyr/Makefile

@@ -33,11 +33,13 @@ INC += -I$(ZEPHYR_BASE)/net/ip/contiki
 INC += -I$(ZEPHYR_BASE)/net/ip/contiki/os
 
 SRC_C = main.c \
+	help.c \
 	uart_core.c \
 	lib/utils/stdout_helpers.c \
 	lib/utils/printf.c \
 	lib/utils/pyexec.c \
 	lib/utils/interrupt_char.c \
+	lib/utils/pyhelp.c \
 	lib/mp-readline/readline.c \
 	$(BUILD)/frozen.c \
 	$(SRC_MOD)

zephyr/help.c

+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013-2016 Damien P. George
+ *
+ * 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 <stdio.h>
+
+#include "lib/utils/pyhelp.h"
+
+STATIC const char *help_text =
+"Welcome to MicroPython!\n"
+"\n"
+"Control commands:\n"
+"  CTRL-A        -- on a blank line, enter raw REPL mode\n"
+"  CTRL-B        -- on a blank line, enter normal REPL mode\n"
+"  CTRL-C        -- interrupt a running program\n"
+"  CTRL-D        -- on a blank line, do a soft reset of the board\n"
+"  CTRL-E        -- on a blank line, enter paste mode\n"
+"\n"
+"For further help on a specific object, type help(obj)\n"
+;
+
+STATIC mp_obj_t builtin_help(uint n_args, const mp_obj_t *args) {
+    if (n_args == 0) {
+        // print a general help message
+        printf("%s", help_text);
+
+    } else {
+        // try to print something sensible about the given object
+        pyhelp_print_obj(args[0]);
+    }
+
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_builtin_help_obj, 0, 1, builtin_help);

zephyr/mpconfigport.h

@@ -51,3 +51,8 @@ typedef long mp_off_t;
 
 // Include Zephyr's autoconf.h, which should be made first by Zephyr makefiles
 #include "autoconf.h"
+
+// extra built in names to add to the global namespace
+#define MICROPY_PORT_BUILTINS \
+    { MP_OBJ_NEW_QSTR(MP_QSTR_help), (mp_obj_t)&mp_builtin_help_obj }, \
+