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cmd_setexpr: allow memory addresses in expressions

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This patch add functionality to use memory addresses in expressions.
This increases the power of expressions substantially

It adheres to the standard convemtions: memory addresses can be given
in the format *address (e.g. *1000)

Rationale for this change is that it allows masking off bits from a
byte that is obtained by reading data from e.g. i2c.

Signed-off-by: Frans Meulenbroeks <fransmeulenbroeks@gmail.com>

Fix warning: control reaches end of non-void function
Signed-off-by: Wolfgang Denk <wd@denx.de>
This commit is contained in:
Frans Meulenbroeks 2010-02-26 14:00:19 +01:00 committed by Wolfgang Denk
parent 652e53546b
commit 47ab5ad145
1 changed files with 30 additions and 4 deletions
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34
common/cmd_setexpr.c
View file

@ -28,10 +28,33 @@
#include <config.h>
#include <command.h>
static ulong get_arg(char *s, int w)
{
ulong *p;
/*
* if the parameter starts with a '*' then assume
* it is a pointer to the value we want
*/
if (s[0] == '*') {
p = (ulong *)simple_strtoul(&s[1], NULL, 16);
switch (w) {
case 1: return((ulong)(*(uchar *)p));
case 2: return((ulong)(*(ushort *)p));
case 4:
default: return(*p);
}
} else {
return simple_strtoul(s, NULL, 16);
}
}
int do_setexpr(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
{
ulong a, b;
char buf[16];
int w;
/* Validate arguments */
if ((argc != 5) || (strlen(argv[3]) != 1)) {
@ -39,8 +62,10 @@ int do_setexpr(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
return 1;
}
a = simple_strtoul(argv[2], NULL, 16);
b = simple_strtoul(argv[4], NULL, 16);
w = cmd_get_data_size(argv[0], 4);
a = get_arg(argv[2], w);
b = get_arg(argv[4], w);
switch (argv[3][0]) {
case '|': sprintf(buf, "%lx", (a | b)); break;
@ -64,7 +89,8 @@ int do_setexpr(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
U_BOOT_CMD(
setexpr, 5, 0, do_setexpr,
"set environment variable as the result of eval expression",
"name value1 <op> value2\n"
"[.b, .w, .l] name value1 <op> value2\n"
" - set environment variable 'name' to the result of the evaluated\n"
" express specified by <op>. <op> can be &, |, ^, +, -, *, /, %"
" express specified by <op>. <op> can be &, |, ^, +, -, *, /, %\n"
" size argument is only meaningful if value1 and/or value2 are memory addresses"
);