[myhdl-list] intbv with max != 2**n. Error or annoyance?

[Per K. <bas...@gm...>]

Hi!
Here is something that I can't make up my mind if it is an error or just
plain annoying:

I have a signal where the max value is not an even 2**n, and I
combinatorically assign it the value of a signal with a higher max value,
but only on the condition that the value is within range. This is fine.

But if the condition is moved to a separate @always_comb driving a flag and
the flag gates the assignment, then there is a ValueError. The generated
verilog is fine of course.
/Per

ps. Here is an example:

from myhdl import *

def range_check(capped, clk, rstn, cnt_max):
    cnt       = Signal(intbv(0, min=0, max=cnt_max))
    less_flag = Signal(intbv(0)[1:0])

    cnt_max      = cnt.max
    capped_max   = capped.max
    capped_width = len(capped)

    @always(clk.posedge, rstn.negedge)
    def count():
        if rstn==0:
            cnt.next = 0
        else:
            if cnt + 1 == cnt_max:
                cnt.next = 0
            else:
                cnt.next = cnt + 1

    @always_comb
    def setcapped():
        if less_flag==1:
            capped.next = cnt[capped_width:]
        else:
            capped.next = 0

    @always_comb
    def setless():
        if cnt < capped_max:
            less_flag.next = 1
        else:
            less_flag.next = 0

    return instances()

def tb(capped_max):
    clk   = Signal(intbv(0)[1:0])
    rstn  = Signal(intbv(0)[1:0])

    @instance
    def rstngen():
        rstn.next = 0
        yield delay(100)
        rstn.next = 1
        yield delay(10000)
        raise StopSimulation

    @always(delay(10))
    def clkgen():
        clk.next = not clk

    capped  = Signal(intbv(0, min=0, max=capped_max))
    cnt_max = 15
    dut   = range_check(capped, clk, rstn, cnt_max)
    return instances()

s = Simulation(tb(4))
s.run()
print "4 is OK"
s = Simulation(tb(5))
s.run()
print "5 is not"