diff --git a/ieee1364-notes.txt b/ieee1364-notes.txt index b2dd2b847..a91a52966 100644 --- a/ieee1364-notes.txt +++ b/ieee1364-notes.txt @@ -140,8 +140,32 @@ integers is unspecified. This, by the way, also applies to module ports. -$Id: ieee1364-notes.txt,v 1.2 2000/11/19 22:03:04 steve Exp $ +* ROUNDING OF TIME + +When the `timescale directive is present, the compiler is supposed to +round fractional times (after scaling) to the nearest integer. The +confusing bit here is that it is apparently conventional that if the +`timescale directive is *not* present, times are rounded towards zero +always. + + +* VALUE OF X IN PRIMITIVE OUTPUTS + +The IEEE1364-1995 standard clearly states in Table 8-1 that the x +symbols is allowed in input columns, but is not allowed in +outputs. Furthermore, none of the examples have an x in the output of +a primitive. Table 8-1 in the IEEE1364-2000 also says the same thing. + +However, the BNF clearly states that 0, 1, x and X are valid +output_symbol characters. The standard is self contradictory. So I +take it that x is allowed, as that is what Verilog-XL does. + + +$Id: ieee1364-notes.txt,v 1.3 2000/12/15 00:21:46 steve Exp $ $Log: ieee1364-notes.txt,v $ +Revision 1.3 2000/12/15 00:21:46 steve + rounding of time and x in primitives. + Revision 1.2 2000/11/19 22:03:04 steve Integer parameter comments.