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 ---
common/cmd_setexpr.c | 29 +++++++++++++++++++++++++---- 1 files changed, 25 insertions(+), 4 deletions(-)
diff --git a/common/cmd_setexpr.c b/common/cmd_setexpr.c index f8b5d4d..86e371b 100644 --- a/common/cmd_setexpr.c +++ b/common/cmd_setexpr.c @@ -28,10 +28,28 @@ #include <config.h> #include <command.h>
+static ulong get_arg(char *s, int w) +{ + ulong *p; + + /* if the parameter starts with a * then assume 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: 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 +57,10 @@ 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 +84,8 @@ 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" );