elbpcom: add a --size argument

Normally elbpcom looks up the preferred transfer size of the selected
memory space in the memory space's info area.

Specifying the transfer size on the command line makes elbpcom skip this
step, and use the specified size directly.

Author: SebKuzminsky

docs/man/man1/elbpcom.1

@@ -10,6 +10,7 @@ Common options:
 .BI [\-\-port= PORT ]
 .BI [\-\-timeout= TIMEOUT ]
 .BI [\-\-space= MEMSPACE ]
+.BI [\-\-size= TRANSFER_SIZE ]
 .RE
 
 Reading data:
@@ -54,8 +55,15 @@ If not specified, the default values are
 .BI \-\-port= 27181
 .BI \-\-timeout= .2
 .BI \-\-space= 0
+.BI \-\-size= 0
 .RE 
 
+If the
+.B --size
+argument
+.I TRANSFER_SIZE
+is 0, elbpcom will look up the preferred transfer size of the space in the space's info area.
+
 This example demonstrates reading the HOSTMOT2 identifying string from the
 IDROM in space 0:
 .RS

src/hal/utils/elbpcom.py

@@ -46,6 +46,9 @@
 parser.add_option("-n", "--no-increment", dest="increment",
     action="store_false",
     help="do not auto-increment address")
+parser.add_option("--size", dest="size",
+    help="Transfer size in number of bytes (default: look up preferred transfer size in the space's info area)",
+    type="int", default=0)
 parser.add_option("-r", "--read", type="int", dest="read", default=None,
     help="Number of bytes to read")
 parser.add_option("-w", "--write", type="string", dest="write", default=None,
@@ -109,16 +112,18 @@ def optimal_size(space:int, info:bool, address:int, nbytes:int):
 
 if options.read:
     if options.address is None: raise SystemExit("--read must specify --address")
-    size = optimal_size(options.space, options.info, options.address, options.read if options.increment else 0)
-    command = make_read_request(options.space, options.info, size, options.increment, options.address, options.read)
+    if options.size == 0:
+        options.size = optimal_size(options.space, options.info, options.address, options.read if options.increment else 0)
+    command = make_read_request(options.space, options.info, options.size, options.increment, options.address, options.read)
     print(">", command.hex())
     transact(command)
 
 elif options.write:
     if options.address is None: raise SystemExit("--write must specify --address")
     write = bytes.fromhex(options.write)
-    size = optimal_size(options.space, options.info, options.address, len(write) if options.increment else 0)
-    command = make_write_request(options.space, options.info, size, options.increment, options.address, write)
+    if options.size == 0:
+        options.size = optimal_size(options.space, options.info, options.address, len(write) if options.increment else 0)
+    command = make_write_request(options.space, options.info, options.size, options.increment, options.address, write)
     print(">", command.hex())
     transact(command, response=False)