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: &, |, +, -, *, /.

---

I'd like to add this to the default command set in include/config_cmd_default.h but wanted to get feedback on the command before doing that.

common/Makefile | 1 + common/cmd_expr.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 70 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..d9233df --- /dev/null +++ b/common/cmd_expr.c @@ -0,0 +1,69 @@ +/* + * 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)) { + 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; + 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" +);