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.. SPDX-License-Identifier: GPL-2.0+:
cmp command
===========
Synopsis
--------
::
cmp [.b, .w, .l, .q] addr1 addr2 count
Description
-----------
The cmp command is used to compare two memory areas. By default it works on
four byte (32-bit) values. By appending .b, .w, .l, .q the size of the
values is controlled:
cmp.b
compare 1 byte (8-bit) values
cmp.w
compare 2 byte (16-bit) values
cmp.l
compare 4 byte (32-bit) values
cmp.q
compare 8 byte (64-bit) values
The parameters are used as follows:
addr1
Address of the first memory area.
addr2
Address of the second memory area.
count
Number of bytes to compare (as hexadecimal number).
Example
-------
In the example below the strings "Hello world\n" and "Hello World\n" are written
to memory and then compared.
::
=> mm.b 0x1000000
01000000: 00 ? 48
01000001: 00 ? 65
01000002: 00 ? 6c
01000003: 00 ? 6c
01000004: 00 ? 6f
01000005: 00 ? 20
01000006: 00 ? 77
01000007: 00 ? 6f
01000008: 00 ? 72
01000009: 00 ? 6c
0100000a: 00 ? 64
0100000b: 00 ? 0d
0100000c: 00 ? => <INTERRUPT>
=> mm.b 0x101000
00101000: 00 ? 48
00101001: 00 ? 65
00101002: 00 ? 6c
00101003: 00 ? 6c
00101004: 00 ? 6f
00101005: 00 ? 20
00101006: 00 ? 57
00101007: 00 ? 6f
00101008: 00 ? 72
00101009: 00 ? 6c
0010100a: 00 ? 64
0010100b: 00 ? 0d
0010100c: 00 ? => <INTERRUPT>
=> cmp 0x1000000 0x101000 0xc
word at 0x01000004 (0x6f77206f) != word at 0x00101004 (0x6f57206f)
Total of 1 word(s) were the same
=> cmp.b 0x1000000 0x101000 0xc
byte at 0x01000006 (0x77) != byte at 0x00101006 (0x57)
Total of 6 byte(s) were the same
=> cmp.w 0x1000000 0x101000 0xc
halfword at 0x01000006 (0x6f77) != halfword at 0x00101006 (0x6f57)
Total of 3 halfword(s) were the same
=> cmp.l 0x1000000 0x101000 0xc
word at 0x01000004 (0x6f77206f) != word at 0x00101004 (0x6f57206f)
Total of 1 word(s) were the same
=> cmp.q 0x1000000 0x101000 0xc
double word at 0x01000000 (0x6f77206f6c6c6548) != double word at 0x00101000 (0x6f57206f6c6c6548)
Total of 0 double word(s) were the same
Configuration
-------------
The cmp command is only available if CONFIG_CMD_MEMORY=y. The cmp.q command is
only available if additionally CONFIG_MEM_SUPPORT_64BIT_DATA=y.
Return value
------------
The return value $? is true (0) if the compared memory areas are equal.
The reutrn value is false (1) if the compared memory areas differ.
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