Re: [Simulavr-devel] [PATCH] use static callbacks instead of template param for IOReg

[panic]

Michael Hennebry:
> Would something like this help:
[snip]

To me this looks a bit like reinventing std::function/std::bind.

But I'd do something similar to your proposal, using std::function that
was added in C++11. GCC in current Debian stable is 6.3.0. Since GCC/g++
6, -std= defaults to c++14, so the feature is available for free:

http://en.cppreference.com/w/cpp/utility/functional


Step 1:
------
In IOReg class remove the template parameter and change the
getter_t/setter_t to:

  typedef std::function<unsigned char(void)> getter_t;
  typedef std::function<void(unsigned char)> setter_t;


Step 2:
------
Peripherals then need to be updated like this:
    ddr_reg(this, "DDR",
-           this, &HWPort::GetDdr, &HWPort::SetDdr),
+           std::bind(&HWPort::GetDdr, this),
+           std::bind(&HWPort::SetDdr, this, std::placeholders::_1))

Up to here, I've already implemented it. Testsuite runs through mostly
fine*. A patch is attached.

Step 3:
------
Add a set_bit(unsigned char bitpos, bool val) to IOReg, provide RMW
default implementation if no specific callback for Set_bit was given.
Then fix the insn decoder in AvrDevice.


Discussion:
----------
The syntax could be simpified if the IOReg itself (or RWMemoryMember)
handled their unsigned char value themselves, instead of being a wrapper
to get/set callbacks. We could then change the implementation of IOReg
to just trigger "OnWrite" or "OnRead" callbacks that don't need any
parameters, thus, we could omit the std::placeholders::_1.
The IOReg/RWMemoryMember would then also make sure that the tracers are
updated, which should avoid bugs related to wrong/forgotten tracing as
it already happend multiple times.


Cheers,
panic


*:
I'm getting a testsuite error with the normal HEAD that also appears
with my patch. To me, the test case seems to have a one-off issue. When
I add round() to the testcase, they run fine:

> ----------------------- regress/modtest/adc_diff_t25.py 
> -----------------------
> @@@ -46,7 -46,7 +46,7 @@@ class TestCase(SimTestCase)
>      else:
>        rng = 512
>      v = self.sim.getWordByName(self.dev, "adc_value")
> -    e = int(((pValue - nValue) / refValue) * rng) & 0x3ff
> +    e = int(round((pValue - nValue) / refValue)) * rng) & 0x3ff
>      self.assertEqual(v, e, "expected adc value is 0x%x, got 0x%x" % (e, v))
>  
>    def test_00(self):

Since the upgrade to GCC 6, I see another testsuite error (already
occurs when run on HEAD, independent of my changes):

> ======================================================================
> FAIL: test_00 (eeprom.TestCase)
> eeprom_atmega16::check read and write eeprom data
> ----------------------------------------------------------------------
> Traceback (most recent call last):
>   File "eeprom.py", line 70, in test_00
>     self.assertValue(0x66)
>   File "eeprom.py", line 19, in assertValue
>     self.assertComplete()
>   File "eeprom.py", line 16, in assertComplete
>     self.assertEqual(c, 1, "function isn't complete (complete=%d)" % c)
> AssertionError: function isn't complete (complete=2)
> 
> ======================================================================
> FAIL: test_00 (eeprom.TestCase)
> eeprom_atmega128::check read and write eeprom data
> ----------------------------------------------------------------------
> Traceback (most recent call last):
>   File "eeprom.py", line 54, in test_00
>     self.assertValue(0x33)
>   File "eeprom.py", line 19, in assertValue
>     self.assertComplete()
>   File "eeprom.py", line 16, in assertComplete
>     self.assertEqual(c, 1, "function isn't complete (complete=%d)" % c)
> AssertionError: function isn't complete (complete=2)
> 
> ----------------------------------------------------------------------

0003-use-std-function-instead-of-template-class-for-IOReg.patch
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