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Full Discussion: C++, std:ofstream, and controlling an amplifiers mute function
Top Forums Programming C++, std:ofstream, and controlling an amplifiers mute function Post 303029758 by Circuits on Thursday 31st of January 2019 03:18:29 PM
Old 01-31-2019
C++, std:ofstream, and controlling an amplifiers mute function
Recently, I updated the unit I am running applications on with a new CODEC and amplifier; the older parts are EOL. There was a bug with the old setup. For some reason, even when a tone was not being generated, you could hear a noise emanating from the speaker when the LCD brightness was on a higher setting.


In order to counteract that problem the Amplifiers mute function (standby for old amp) was toggled on and off before and after a tone was produced:


Code:
const char *const amplifierGPIO = "/sys/class/gpio/gpio107/value";

    void amplifierOn()
    {
      std::ofstream amp(amplifierGPIO);
      if (amp.is_open())
      {
        amp << "1";
        amp.close();
      }
    }

    void amplifierOff()
    {
      std::ofstream amp(amplifierGPIO);
      if (amp.is_open())
      {
        amp << "0";
        amp.close();
      }
     }

The problem is that now in order to get the same functionality to work with the new amplifier I have to surround the ofstream in sleep statments:


Code:
const char *const amplifierGPIO = "/sys/class/gpio/gpio107/value";

    void amplifierOn()
    {
      sleep(1);
      std::ofstream amp(amplifierGPIO);
      if (amp.is_open())
      {
        amp << "1";
        amp.close();
      }
      sleep(1);
    }

    void amplifierOff()
    {
      sleep(1):
      std::ofstream amp(amplifierGPIO);
      if (amp.is_open())
      {
        amp << "0";
        amp.close();
      }
      sleep(1);
     }

1) Any ideas about why this might be the case? I do not believe it's the mute function on the amplifier itself because outside of the application that uses this ofstream (inside the boot loader) I can play a song and toggle it on and off with the mute function, with no delay needed.


2) Is there another way (other than ofstream) of toggling the GPIO pin 107 from within my application?
 

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LEARN ABOUT CENTOS

std::gslice_array

std::gslice_array< _Tp >(3)				     Library Functions Manual				       std::gslice_array< _Tp >(3)

NAME

       std::gslice_array< _Tp > -

SYNOPSIS

   Public Types
       typedef _Tp value_type

   Public Member Functions
       gslice_array (const gslice_array &)
       void operator%= (const valarray< _Tp > &) const
       template<class _Dom > void operator%= (const _Expr< _Dom, _Tp > &) const
       void operator&= (const valarray< _Tp > &) const
       template<class _Dom > void operator&= (const _Expr< _Dom, _Tp > &) const
       void operator*= (const valarray< _Tp > &) const
       template<class _Dom > void operator*= (const _Expr< _Dom, _Tp > &) const
       void operator+= (const valarray< _Tp > &) const
       template<class _Dom > void operator+= (const _Expr< _Dom, _Tp > &) const
       void operator-= (const valarray< _Tp > &) const
       template<class _Dom > void operator-= (const _Expr< _Dom, _Tp > &) const
       void operator/= (const valarray< _Tp > &) const
       template<class _Dom > void operator/= (const _Expr< _Dom, _Tp > &) const
       void operator<<= (const valarray< _Tp > &) const
       template<class _Dom > void operator<<= (const _Expr< _Dom, _Tp > &) const
       gslice_array & operator= (const gslice_array &)
       void operator= (const valarray< _Tp > &) const
       void operator= (const _Tp &) const
       template<class _Dom > void operator= (const _Expr< _Dom, _Tp > &) const
       void operator>>= (const valarray< _Tp > &) const
       template<class _Dom > void operator>>= (const _Expr< _Dom, _Tp > &) const
       void operator^= (const valarray< _Tp > &) const
       template<class _Dom > void operator^= (const _Expr< _Dom, _Tp > &) const
       void operator|= (const valarray< _Tp > &) const
       template<class _Dom > void operator|= (const _Expr< _Dom, _Tp > &) const

   Friends
       class valarray< _Tp >

Detailed Description
   template<class _Tp>class std::gslice_array< _Tp >
       Reference to multi-dimensional subset of an array.

       A gslice_array is a reference to the actual elements of an array specified by a gslice. The way to get a gslice_array is to call
       operator[](gslice) on a valarray. The returned gslice_array then permits carrying operations out on the referenced subset of elements in
       the original valarray. For example, operator+=(valarray) will add values to the subset of elements in the underlying valarray this
       gslice_array refers to.

       Parameters:
	   Tp Element type.

       Definition at line 82 of file valarray.

Author
       Generated automatically by Doxygen for libstdc++ from the source code.

libstdc++							  Tue Jun 10 2014				       std::gslice_array< _Tp >(3)
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