.. 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 tuples. By appending .b, .w, .l, .q the size of the tuples is
controlled:

cmp.b
    compare 1 byte tuples

cmp.w
    compare 2 byte tuples

cmp.l
    compare 4 byte tuples

cmp.q
    compare 8 byte tuples

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.