[PATCH] doc: cmd: add documentation for binop

["Maxin B. John" <maxin.john@gmail.com>]

Add documentation for the binop command.

Signed-off-by: Maxin B. John <maxin.john@gmail.com>
---
 doc/usage/cmd/binop.rst | 103 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)
 create mode 100644 doc/usage/cmd/binop.rst

diff --git a/doc/usage/cmd/binop.rst b/doc/usage/cmd/binop.rst
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+.. SPDX-License-Identifier: GPL-2.0+
+
+.. index::
+   single: binop (command)
+
+binop command
+=============
+
+Synopsis
+--------
+
+::
+
+    binop op count src1 src2 [dest]
+
+Description
+-----------
+
+The binop command applies a bitwise binary operation to two byte arrays of
+count bytes. Bytes are processed independently; no endian or word-size
+conversion is performed. The result is written to dest or, if dest is
+omitted, printed to the console.
+
+op
+    Operation to perform:
+
+    * ``xor`` - set each bit where the operands differ
+    * ``or`` - set each bit that is set in either operand
+    * ``and`` - set each bit that is set in both operands
+
+count
+    Number of bytes to process, specified in decimal. Must be
+    greater than zero.
+
+src1, src2
+    Input operands. Each operand is either:
+
+    - an environment variable name, whose value is parsed as a hex string
+    - a hex string, if no environment variable with that name exists
+    - a memory address prefixed with '*', in which case count bytes are
+      read from that address
+
+    An existing environment variable takes precedence over interpreting
+    the argument as a hex string. Prefixing an argument with ``*``
+    explicitly selects memory access. Hex strings must contain an even
+    number of hexadecimal digits and may not describe more than count
+    bytes. Shorter values are zero-padded at the end.
+
+dest
+    Optional destination. If prefixed with '*', the result is written to
+    that memory address. Otherwise dest is the name of an environment
+    variable which receives the result as a lowercase hex string with two
+    hex digits per byte. If dest is omitted, the result is printed as hex
+    bytes separated by spaces, 16 bytes per line.
+
+Addresses are parsed as hexadecimal numbers. The caller is responsible
+for ensuring that the specified memory is accessible and, for
+destinations, writable.
+
+Invalid counts, operators, addresses or hex strings are rejected and the
+destination is left unchanged.
+
+Examples
+--------
+
+XOR two hex strings and store the result in an environment variable::
+
+    => binop xor 4 01020304 ffffffff binop_out
+    => printenv binop_out
+    binop_out=fefdfcfb
+
+AND two hex strings::
+
+    => binop and 4 0f0f0f0f 00ff00ff binop_out
+    => printenv binop_out
+    binop_out=000f000f
+
+Read an operand from an environment variable. The short value is
+zero-padded::
+
+    => setenv binop_a 0102
+    => binop or 4 binop_a 03 binop_out
+    => printenv binop_out
+    binop_out=03020000
+
+Print the result to the console::
+
+    => binop xor 2 0102 0304
+    02 06
+
+Read from and write to memory (addresses are hexadecimal)::
+
+    => binop xor 4 *0x80000000 01010101 *0x80000010
+
+Configuration
+-------------
+
+The binop command is available if CONFIG_CMD_BINOP=y.
+
+Return value
+------------
+
+The return value $? is 0 on success and 1 on failure.
-- 
2.47.3