Add setexpr command

Add a simple expr style command that will set an env variable as the result
of the command.  This allows us to do simple math in shell.  The following
operations are supported: &, |, ^, +, -, *, /.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

common/Makefile

@@ -88,6 +88,7 @@ COBJS-$(CONFIG_CMD_REGINFO) += cmd_reginfo.o
 COBJS-$(CONFIG_CMD_REISER) += cmd_reiser.o
 COBJS-y += cmd_sata.o
 COBJS-$(CONFIG_CMD_SCSI) += cmd_scsi.o
+COBJS-$(CONFIG_CMD_SETEXPR) += cmd_setexpr.o
 COBJS-$(CONFIG_CMD_SPI) += cmd_spi.o
 COBJS-$(CONFIG_CMD_STRINGS) += cmd_strings.o
 COBJS-$(CONFIG_CMD_TERMINAL) += cmd_terminal.o

common/cmd_setexpr.c

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2008 Freescale Semiconductor, Inc.
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+/*
+ * This file provides a shell like 'expr' function to return.
+ */
+
+#include <common.h>
+#include <config.h>
+#include <command.h>
+
+int do_setexpr(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+{
+	ulong a, b;
+	char buf[16];
+
+	/* Validate arguments */
+	if ((argc != 5) || (strlen(argv[3]) != 1)) {
+		printf("Usage:\n%s\n", cmdtp->usage);
+		return 1;
+	}
+
+	a = simple_strtoul(argv[2], NULL, 16);
+	b = simple_strtoul(argv[4], NULL, 16);
+
+	switch (argv[3][0]) {
+	case '|': sprintf(buf, "%lx", (a | b)); break;
+	case '&': sprintf(buf, "%lx", (a & b)); break;
+	case '+': sprintf(buf, "%lx", (a + b)); break;
+	case '^': sprintf(buf, "%lx", (a ^ b)); break;
+	case '-': sprintf(buf, "%lx", (a - b)); break;
+	case '*': sprintf(buf, "%lx", (a * b)); break;
+	case '/': sprintf(buf, "%lx", (a / b)); break;
+	case '%': sprintf(buf, "%lx", (a % b)); break;
+	default:
+		printf("invalid op\n");
+		return 1;
+	}
+
+	setenv(argv[1], buf);
+
+	return 0;
+}
+
+U_BOOT_CMD(
+	setexpr, 5, 0, do_setexpr,
+	"setexpr - set environment variable as the result of eval expression\n",
+	"name value1 <op> value2\n"
+	"    - set environment variable 'name' to the result of the evaluated\n"
+	"      express specified by <op>.  <op> can be &, |, ^, +, -, *, /, %\n"
+);

include/config_cmd_all.h

@@ -70,6 +70,7 @@
 #define CONFIG_CMD_SAVES	/* save S record dump		*/
 #define CONFIG_CMD_SCSI		/* SCSI Support			*/
 #define CONFIG_CMD_SDRAM	/* SDRAM DIMM SPD info printout */
+#define CONFIG_CMD_SETEXPR	/* setexpr support 		*/
 #define CONFIG_CMD_SETGETDCR	/* DCR support on 4xx		*/
 #define CONFIG_CMD_SNTP		/* SNTP support			*/
 #define CONFIG_CMD_SPI		/* SPI utility			*/