WingNews logo WingNews GitHub [2]

codehero's comments

codehero | 3 days ago | on: TCXO Failure Analysis

Depends on the quality of the solder joint. Poor quality solder joints do not survive mechanical shock. If you are fighting a GND pin that sinks a lot of heat, using leadfree solder and you aren't that skilled...don't trim that lead flush with the PCB. Otherwise, if you are sure that the solder has wicked into the hole, trim away.

So if someone is telling you not to trim the lead...I'll let you draw your own conclusion.

codehero | 2 years ago | on: Ubus (OpenWrt micro bus architecture)

Pipes and named FIFOs are easy and great. I say this after implementing various IPC methods (unix domain sockets with fd passing, POSIX message queues, 0MQ, XML RPC, local TCP sockets, just to name a few). Use a simple line oriented protocol. If you are passing complex data through your IPC, you know it's time for files. Shared memory is another way to do IPC but hopefully you have robust method of detecting the liveliness of your local processes and you want to give up the Unix file paradigm.

codehero | 6 years ago | on: Efficient string copying and concatenation in C

Safe string manipulation never exceeds the bounds of the buffer. So negative values are dangerous, as all as any additions that would exceed the maximum size.

Negative lengths are not compatible with unsigned representation.

A system implementing invalid string values must choose a text encoding such as UTF-8 that supports the concept of an invalid character. Null termination is too flexible. As such is simple length prepending.

codehero | 6 years ago | on: Efficient string copying and concatenation in C

If you have studied Computer Science, you should know that the null string is quite a valid string.

Let's take strstr, which finds a matching substring needle in a haystack string.

-returns a NULL string if the needle is not in the haystack. -returns pointer to first matching substring.

Extend strstr with VALIDITY

Understood behaviour if both are valid.

Say the haystack is INVALID...as the return value is NULL or a strict substring of haystack, should return INVALID. A poison haystack should poison dependent strings.

Say the haystack is valid but the needle is INVALID...should return NULL. A valid string never contains an INVALID string as a subsequence.

codehero | 6 years ago | on: Efficient string copying and concatenation in C

Is it more sensible to cat 2 strings, but cut off the second one, then pass off the result as valid?

I would say let an INVALID string be length 0. Then accept that catting a valid and invalid string would result in a shorter length.

Which one do you think is safer?

codehero | 6 years ago | on: Efficient string copying and concatenation in C

I don't understand the fallibility. Clearly misuse of string functions is epidemic. A propagating INVALID string result makes it very clear there is a logic error and not an exploit.

I understand how one could shoot down implementations, but none has made a convincing argument about shooting down the idea.

codehero | 6 years ago | on: Efficient string copying and concatenation in C

Efficiency looks past current deficiency.

We have the empty string: "\0"

We have the null string: NULL

There is no concept of an INVALID string, as float has NAN.

This would be the result of trying to copy a string to a buffer that is too small.

Or sprintf() into a small buffer.

Or a raw string parsed as UTF-8 and is invalid.

Correctness over efficiency.

codehero | 7 years ago | on: Guide to Implementing Communication Protocols in C++ for Embedded Systems

I tried really hard to find a main() function browsing the demo source code, but I could not. I also find it interesting that code boilerplating is called out as a problem, but I run into code like this:

  #include "Protocol.h"

  #include "comms/comms.h"

  namespace cc = comms_champion;

  namespace demo
  {

  namespace cc_plugin
  {

  Protocol::~Protocol() noexcept = default;

  const QString& Protocol::nameImpl() const
  {
      static const QString& Str("Demo");
      return Str;
  }

  }  // namespace cc_plugin

  }  // namespace demo

codehero | 7 years ago | on: Minimalist C Libraries

Choose the size representation that bests fits your use case:

  // Put this in header to help user calculate allocation needs but hide size from user
  size_t LIBNAME_alloc_size(param1, param2, ...);

  // Put this in the header to hide the size from user code but allow inlined size calculations
  extern const size_t LIBNAME_ALLOC_X;

  // Put this in the header to make size known to user (for static const allocation)
  #define LIBNAME_ALLOC_Y ((size_t)42)

codehero | 9 years ago | on: Ncollide – 2D and 3D collision detection library

Sell me: I am a crusty old C++ programmer who started numerical and geometric programming on an SGI machine at the turn of the century. I have seen many academic and commercial 3D libraries come, go or perform poorly (vcollide, RAPID, CGAL and many proprietary ones).

It looks interesting but what makes this library any better than what's come before? Why should I learn Rust to use it or really for any computational geometry problem?

page 1
more