This patch makes sure the delay is calculated correctly when only some
of the bits change and you are comparing against the initial (t0) value.
Basically you have to check the initial value against all the bits in
the new signal not just the first bit since the order that bits change
is not deterministic.
This patch add delays in continuous assignments for the shift operators,
concatenations and replications. It also reports an error if the user
attempts to take the modulus of a real value.
This patch uncovers a couple other problems in the system. I am trying
to fix one of them. I will report the other problem shortly.
This patch fixes some of the delays in bit based continuous
assignments (unary -, unary +constants, string constants,
reduction operators and user functions).
Use draw_lpm_output_delay() in all functions that need it.
Addresses pr1879226 on a couple of levels. Analysis:
NetNet* PEBinary::elaborate_net_shift_() didn't flag dist==lwidth
as a case where all bits of the input are shifted away, which made
it create a real concatenator for this case. It attempted to create
NetNet*tmp with zero width, which doesn't work; (lsb,msb) ends up
as (0,-1), which is later interpreted as a 2-bit wide net.
Added an assert to the NetNet constructor to catch any other lurking
attempts to create zero-width nets.
Added short-circuit code to handle the case where all bits of the input
are shifted away. This case used to be "handled" by an assert failure.
When used in continuous assignments, user defined functions may have
delayed output. Handle that by generating the proper .delay node when
needed to delay the output of a .ufunc node.
Allow user defined functions to take real value arguments and return
real value results in net contexts. Use the data type of the nets
attached to the ports to define the data types of the arguments and
return value.
There was much redundant code in the compile-tile handling of the
less-then and greater-then of constant expressions, and much of it
was buggy. Unify much of the code and squeeze out the bugs so that
compile-time evaluations come out correctly.
The compiler attempts to precalculate the results of <= comparisons.
Fix a few corner cases where the arguments are signed. Also fix the
important test of constant against non-constant where we try to test
if the non-constant value can possibly make the test fail.
When conditional delays are in use, it is sometimes possible for there
to be no delays available for a given input event. In that case, skip
the delay processing for that case instead of crashing.
Previously only the logical operators (~, &, |, ^, etc.) supported a
delayed value in a continuous assignment. This patch should extend this
to all operators. An extensive check of real values was done. The same
will be done shortly for bit based nets.
Checks for constructs currently unsupported in continuous assignments
provide a more explicit message (** operator, real user functions,
{!, && and ||} operators with a real argument).
Rework the encoding of a real value in the Cr<> label to be similar to
the format used by the %loadi/wr instruction. This mantissa-expoment
format better carries all the bits of the desired real value with
plenty of fidelity and range.
The continuous assignment multiply expands vectors to the sum
of the two widths. This is correct for bit based vectors, but
for real variables it should always be one bit wide.
The sys_funcs table should be left to those functions that are handled
internally by the compiler. Really, the internal sys_funcs table is a
legacy from the days before the compiler supported system function
tables in the .sft format.
System functions used in a continuous assignment must be defined
in the system function table since the name of the system functions
is kept in this definition. The default name is NULL which causes
problems. This patch add $rtoi to the system table and adds a check
for a NULL name.
The comment that shows the intended value for real constants was
being printed with a %f. This is wrong for large or small values.
This patch changes the %f to a %g to get more consistent results.
A right shift may generate extra bits to preserve the proper shift
characteristic. This patch replaces the assert that was forcing the
input vector to not be greater than the input port width with code
to only select the required lower bits from the vector if it is
larger than the input port.
This patch adds support for the following statement:
<vector>[<i>] <= #<delay> <value>.
It is a copy with slight modification of code from the next
else/if clause.
The nodangle functor tries to delete NetNet objects that are not used.
But NetNet objects that are addressed by a NetArrayDq should never be
dangling. So make sure the NetArrayDq marks the target NetNet correctly.
This patch adds a new opcode %load/avp0 that is used to load a
word from an array and add a value to it. %load/vp0 was
changed/fixed to do the summation at the result width not the
vector width. This allows small vectors to index large arrays with
an offset. A few errors in the opcodes.txt file were also fixed.
In nets, if system functions return a real value the function lookup
was getting the correct width, but was also setting the width to 0,
which confused down-stream net handling. Real-value system fuctions
have a width of 1. (1 real-valued scalar.)
Cary R
Larry Doolittle
Stephen Williams