[U-Boot-Users] [PATCH v2] Add expr command

[U-Boot-Users] [PATCH v2] Add expr command

[Kumar Gala]

Add a simple expr 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>
---

Added xor (^) and check that the op arg is only one char as suggsted by
Andreas.

- k

 common/Makefile   |    1 +
 common/cmd_expr.c |   70 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 71 insertions(+), 0 deletions(-)
 create mode 100644 common/cmd_expr.c

diff --git a/common/Makefile b/common/Makefile
index 1639109..4f3e711 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -54,6 +54,7 @@ COBJS-$(CONFIG_CMD_DOC) += cmd_doc.o
 COBJS-$(CONFIG_CMD_DTT) += cmd_dtt.o
 COBJS-y += cmd_eeprom.o
 COBJS-$(CONFIG_CMD_ELF) += cmd_elf.o
+COBJS-$(CONFIG_CMD_EXPR) += cmd_expr.o
 COBJS-$(CONFIG_CMD_EXT2) += cmd_ext2.o
 COBJS-$(CONFIG_CMD_FAT) += cmd_fat.o
 COBJS-y += cmd_fdc.o
diff --git a/common/cmd_expr.c b/common/cmd_expr.c
new file mode 100644
index 0000000..441865a
--- /dev/null
+++ b/common/cmd_expr.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_expr (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(
+	expr, 5, 0, do_expr,
+	"expr    - 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"
+);
-- 
1.5.3.8

[U-Boot-Users] [PATCH v2] Add expr command

[Kim Phillips]

On Wed, 13 Feb 2008 09:54:31 -0600 (CST)
Kumar Gala <galak@kernel.crashing.org> wrote:

> +}
> +
> +U_BOOT_CMD(
> +	expr, 5, 0, do_expr,
> +	"expr    - 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"

can we at least change the name to "setexpr" or something, so as not
break forward compatibility with any future GNU syntax expr
implementation?

Kim

[U-Boot-Users] [PATCH v2] Add expr command

[Kumar Gala]

On Feb 13, 2008, at 10:35 AM, Kim Phillips wrote:

> On Wed, 13 Feb 2008 09:54:31 -0600 (CST)
> Kumar Gala <galak@kernel.crashing.org> wrote:
>
>> +}
>> +
>> +U_BOOT_CMD(
>> +	expr, 5, 0, do_expr,
>> +	"expr    - 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"
>
> can we at least change the name to "setexpr" or something, so as not
> break forward compatibility with any future GNU syntax expr
> implementation?

ok.  Waiting to here on wd's feeling about having this as part of the  
standard command set or not.

- k

[U-Boot-Users] [PATCH v2] Add expr command

[Wolfgang Denk]

In message <2040FCC8-76A9-4B8E-9F3B-5422EF117F26@kernel.crashing.org> you wrote:
> 
> > can we at least change the name to "setexpr" or something, so as not
> > break forward compatibility with any future GNU syntax expr
> > implementation?
> 
> ok.  Waiting to here on wd's feeling about having this as part of the  
> standard command set or not.

Well, if you ask me, I'd just call it expr.... [I have to admit  that
this  is  for very egoistic reasons, namely being used to type "sete"
fort setenv, which  then  would  be  require  me  to  type  one  more
character. And with my age you don't change such habits easily ;-) ]

Best regards,

Wolfgang Denk

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[U-Boot-Users] [PATCH v2] Add expr command

[Andreas Schweigstill]

Hello!

Kim Phillips schrieb:
> can we at least change the name to "setexpr" or something, so as not
> break forward compatibility with any future GNU syntax expr
> implementation?

+1

Regards
Andreas Schweigstill


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