1 files changed, 93 insertions, 0 deletions
diff --git a/commands/let.c b/commands/let.c
new file mode 100644
index 0000000000..644ede5e2e
--- /dev/null
+++ b/commands/let.c
@@ -0,0 +1,93 @@
+/*
+ * Copyright (C) 2012 Jan Luebbe <j.luebbe@pengutronix.de>
+ *
+ * Partially based on code from BusyBox.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <common.h>
+#include <command.h>
+#include <environment.h>
+#include <errno.h>
+#include <init.h>
+#include <malloc.h>
+#include <xfuncs.h>
+#include <math.h>
+
+static void setvar(const char *name, const char *val)
+{
+	setenv(name, val); /* return value is always 0 */
+}
+
+static arith_t run_arith(const char *s)
+{
+	arith_state_t math_state;
+	arith_t result;
+
+	math_state.lookupvar = getenv;
+	math_state.setvar    = setvar;
+	math_state.endofname = arith_endofname;
+
+	result = arith(&math_state, s);
+	if (math_state.errmsg)
+		printf("let: %s\n", math_state.errmsg);
+
+	return result;
+}
+
+static int do_let(int argc, char *argv[])
+{
+	arith_t i;
+
+	argv++;
+	if (!*argv) {
+		printf("let: expression expected\n");
+		return COMMAND_ERROR_USAGE;
+	}
+
+	do {
+		i = run_arith(*argv);
+	} while (*++argv);
+
+	return !i;
+}
+
+BAREBOX_CMD_HELP_START(let)
+BAREBOX_CMD_HELP_USAGE("let expr [expr ...]\n")
+BAREBOX_CMD_HELP_SHORT("evaluate arithmetic expressions\n")
+BAREBOX_CMD_HELP_TEXT ("supported operations are in order of decreasing precedence:\n")
+BAREBOX_CMD_HELP_TEXT ("	X++, X--\n")
+BAREBOX_CMD_HELP_TEXT ("	++X, --X\n")
+BAREBOX_CMD_HELP_TEXT ("	+X, -X\n")
+BAREBOX_CMD_HELP_TEXT ("	!X, ~X\n")
+BAREBOX_CMD_HELP_TEXT ("	X**Y\n")
+BAREBOX_CMD_HELP_TEXT ("	X*Y, X/Y, X%Y\n")
+BAREBOX_CMD_HELP_TEXT ("	X+Y, X-Y\n")
+BAREBOX_CMD_HELP_TEXT ("	X<<Y, X>>Y\n")
+BAREBOX_CMD_HELP_TEXT ("	X<Y, X<=Y, X>=Y, X>Y\n")
+BAREBOX_CMD_HELP_TEXT ("	X==Y, X!=Y\n")
+BAREBOX_CMD_HELP_TEXT ("	X&Y\n")
+BAREBOX_CMD_HELP_TEXT ("	X^Y\n")
+BAREBOX_CMD_HELP_TEXT ("	X|Y\n")
+BAREBOX_CMD_HELP_TEXT ("	X&&Y\n")
+BAREBOX_CMD_HELP_TEXT ("	X||Y\n")
+BAREBOX_CMD_HELP_TEXT ("	X?Y:Z\n")
+BAREBOX_CMD_HELP_TEXT ("	X*=Y, X/=Y, X%=Y\n")
+BAREBOX_CMD_HELP_TEXT ("	X=Y, X&=Y, X|=Y, X^=Y, X+=Y, X-=Y, X<<=Y, X>>=Y\n")
+BAREBOX_CMD_HELP_END
+
+BAREBOX_CMD_START(let)
+	.cmd            = do_let,
+	.usage          = "evaluate arithmetic expressions",
+	BAREBOX_CMD_HELP(cmd_let_help)
+BAREBOX_CMD_END