19:50 <kernlbob> Is this the place for noob nMigen questions?

19:59 <cr1901_modern> Sure, but you may need to stick around for a while as IRC is async

20:00 <kernlbob> I hope the formatting isn't screwn up too horribly...

20:00 <kernlbob> I have this Verilog.

20:00 <kernlbob> ```

20:00 <kernlbob> module example(

20:00 <kernlbob> input clk,

20:00 <kernlbob> input [15:0] bits,

20:00 <kernlbob> output reg bit);

20:00 <kernlbob> reg [7:0] counter = 0;

20:01 <kernlbob> always @(posedge clk) begin

20:01 <kernlbob> bit <= bits[counter[6:3]];

20:01 <kernlbob> counter <= counter + 1;

20:01 <kernlbob> end

20:01 <kernlbob> endmodule

20:01 <kernlbob> ```

20:01 <kernlbob> I rewrote it in nMigen like this.

20:01 <kernlbob> ```

20:01 <kernlbob> class Example(Elaboratable):

20:01 <kernlbob> def elaborate(self, platform):

20:01 <kernlbob> bits = Signal(16)

20:01 <kernlbob> bit = Signal()

20:01 <kernlbob> counter = Signal(8)

20:01 <kernlbob> m = Module()

20:01 <kernlbob> m.d.comb += [

20:01 <kernlbob> bit.eq(bits[counter[3:7]]),

20:01 <kernlbob> counter.eq(counter + 1),

20:01 <kernlbob> ]

20:01 <kernlbob> ```

20:01 <kernlbob> When I elaborate this, I get

20:01 <kernlbob> TypeError: Cannot index value with (slice (sig counter) 3:7)

20:01 <kernlbob> What should I be doing?

20:02 <cr1901_modern> Huh, this feels like it should be supported

20:03 <cr1901_modern> Maybe the functionality hasn't been added in yet?

20:04 <cr1901_modern> (Along with a elaboration-time check to ensure that the slice is within the range of the signal?)

20:09 <kernlbob> Crap. I put that in m.d.comb for the example. Meant m.d.sync, of course.

20:12 <kernlbob> Any idea how I could express the intent in a way nMigen would accept?

20:16 <cr1901_modern> kernlbob: I think that functionality needs to be added and you'll need to wait for a commit.

20:18 <kernlbob> Is this equivalent?

20:18 <kernlbob> bit.eq(bits.bit_select(counter[3:7], 1)),

20:53 <vup> kernlbob: yeah, normal slices only support constant indices and bit_select (or word_select) is used for non-constant indices

20:55 <vup> alternatively you can also used `Array` which also supports non-constant indices and has special handling for indices bigger than the array length

21:00 <kernlbob> @vup: thanks.