target/tcl: Add 'read_memory' and 'write_memory'

These functions are meant as replacement for 'mem2array' and
'array2mem'.

The main benefits of these new functions are:

 * They do not use Tcl arrays but lists which makes it easier
   to parse (generate) the data. See the Python Tcl RPC code
   in contrib as a negative example.

 * They do not operate on Tcl variables but instead return (accept)
   the Tcl list directly. This makes the C and Tcl code base
   smaller and cleaner.

 * The code is slightly more performant when reading / writing
   large amount of data. Tested with a simple Python Tcl RPC
   benchmark.

Change-Id: Ibd6ece3360c0d002abaadc37f078b10a8bb606f8
Signed-off-by: Marc Schink <dev@zapb.de>
Reviewed-on: https://review.openocd.org/c/openocd/+/6307
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

doc/openocd.texi

@@ -5036,6 +5036,45 @@ get_reg @{pc sp@}
 @end example
 @end deffn
 
+@deffn {Command} {$target_name write_memory} address width data ['phys']
+This function provides an efficient way to write to the target memory from a Tcl
+script.
+
+@itemize
+@item @var{address} ... target memory address
+@item @var{width} ... memory access bit size, can be 8, 16, 32 or 64
+@item @var{data} ... Tcl list with the elements to write
+@item ['phys'] ... treat the memory address as physical instead of virtual address
+@end itemize
+
+For example, the following command writes two 32 bit words into the target
+memory at address 0x20000000:
+
+@example
+write_memory 0x20000000 32 @{0xdeadbeef 0x00230500@}
+@end example
+@end deffn
+
+@deffn {Command} {$target_name read_memory} address width count ['phys']
+This function provides an efficient way to read the target memory from a Tcl
+script.
+A Tcl list containing the requested memory elements is returned by this function.
+
+@itemize
+@item @var{address} ... target memory address
+@item @var{width} ... memory access bit size, can be 8, 16, 32 or 64
+@item @var{count} ... number of elements to read
+@item ['phys'] ... treat the memory address as physical instead of virtual address
+@end itemize
+
+For example, the following command reads two 32 bit words from the target
+memory at address 0x20000000:
+
+@example
+read_memory 0x20000000 32 2
+@end example
+@end deffn
+
 @deffn {Command} {$target_name cget} queryparm
 Each configuration parameter accepted by
 @command{$target_name configure}
@@ -8557,6 +8596,45 @@ get_reg @{pc sp@}
 @end example
 @end deffn
 
+@deffn {Command} {write_memory} address width data ['phys']
+This function provides an efficient way to write to the target memory from a Tcl
+script.
+
+@itemize
+@item @var{address} ... target memory address
+@item @var{width} ... memory access bit size, can be 8, 16, 32 or 64
+@item @var{data} ... Tcl list with the elements to write
+@item ['phys'] ... treat the memory address as physical instead of virtual address
+@end itemize
+
+For example, the following command writes two 32 bit words into the target
+memory at address 0x20000000:
+
+@example
+write_memory 0x20000000 32 @{0xdeadbeef 0x00230500@}
+@end example
+@end deffn
+
+@deffn {Command} {read_memory} address width count ['phys']
+This function provides an efficient way to read the target memory from a Tcl
+script.
+A Tcl list containing the requested memory elements is returned by this function.
+
+@itemize
+@item @var{address} ... target memory address
+@item @var{width} ... memory access bit size, can be 8, 16, 32 or 64
+@item @var{count} ... number of elements to read
+@item ['phys'] ... treat the memory address as physical instead of virtual address
+@end itemize
+
+For example, the following command reads two 32 bit words from the target
+memory at address 0x20000000:
+
+@example
+read_memory 0x20000000 32 2
+@end example
+@end deffn
+
 @deffn {Command} {halt} [ms]
 @deffnx {Command} {wait_halt} [ms]
 The @command{halt} command first sends a halt request to the target,