I was reading carefully the following example taken from here 
<file:///home/wilhem/Downloads/html/button_8c_source.html>:

file: button.c

define _GNU_SOURCE 1 
 #include "stdio.h" 
 #include <termios.h> 
 #include <unistd.h> 
#include <errno.h> 
 #include <sys/types.h> 
#include <sys/time.h> 
 #include "../c_wrapper/pruio.h" 
 #include "../c_wrapper/pruio_pins.h" 
  
 #define PIN P8_07 
 
 int 
 isleep(unsigned int mseconds) 
 { 
 fd_set set; 
  struct timeval timeout; 
  
 /* Initialize the file descriptor set. */ 
  FD_ZERO(&set); 
  FD_SET(STDIN_FILENO, &set); 
  
  /* Initialize the timeout data structure. */ 
 timeout.tv_sec = 0; 
  timeout.tv_usec = mseconds * 1000; 
  
 return TEMP_FAILURE_RETRY(select(FD_SETSIZE, 
 &set, NULL, NULL, 
 &timeout)); 
 } 
  
 int main(int argc, char **argv) 
 { 
 pruIo *io = pruio_new(PRUIO_DEF_ACTIVE, 0x98, 0, 1); // <= LOOK HERE
 
  do { 
  if (io->Errr) { 
  printf("initialisation failed (%s)\n", io->Errr); break;} 
  
  if (pruio_config(io, 1, 0x1FE, 0, 4)) { 
printf("config failed (%s)\n", io->Errr); break;} 
  
 struct termios oldt, newt; // make terminal non-blocking 
 tcgetattr( STDIN_FILENO, &oldt ); 
 newt = oldt; 
 newt.c_lflag &= ~( ICANON | ECHO ); 
 newt.c_cc[VMIN] = 0; 
 newt.c_cc[VTIME] = 0; 
 tcsetattr(STDIN_FILENO, TCSANOW, &newt); 
  
 while(!isleep(1)) { // run loop until keystroke 
 printf("\r%1X", pruio_gpio_Value(io, PIN)); 
 fflush(STDIN_FILENO); 
 } 
 tcsetattr(STDIN_FILENO, TCSANOW, &oldt); // reset terminal 
  
  printf("\n"); 
 } while (0); 
  
 pruio_destroy(io); /* destroy driver structure */ 
 return 0; 
 }


In the following line of code you can read that the value 0x98 is the 
*second* argument passed to the function.
*BUT* In the documentation I found that:

pruIo* pruio_new ( uint16  *Act*, 


uint8  *Av*, 


uint32  *OpD*, 


uint8  *SaD*  

) 

Wrapper function for the constructor PruIo::PruIo(). 
Parameters 
Act mask for active subsystems and PRU number 
Av avaraging for default steps (0 to 16, defaults to 0) 
OpD open delay for default steps (0 to 0x3FFFF, defaults to 0x98) 
SaD sample delay for default steps (0 to 255, defaults to 0) 
the second argument of that function should be the parameter Av, which 
ranges [0-16].
the OpD is passed lately to the function.

Is there a problem in the documentation or somewhere else??


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