cmd_setexpr: allow memory addresses in expressions

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>

diff --git a/common/cmd_setexpr.c b/common/cmd_setexpr.c
index f8b5d4dcfe8cc2f2208a6a59641d5bfb1da519f1..2d3719755e0d6fed3b6734bef16ece0b8e61e4ea 100644 (file)
--- a/common/cmd_setexpr.c
+++ b/common/cmd_setexpr.c
@@ -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"
 );