= Standard 825 Library (lib825) =

[[TOC(heading=Table of Contents, Docs/Prog/Manual/*)]]

The standard library (lib825) is a collection of Cardinal utilities that simplifies the process of writing code for the [[wiki:WikiStart Cardinal 825]]. The library is distributed free of charge and available here to download.

== Utility Functions ==
Some simple routines may be used in the apps to convert between the hexadecimal strings and the various structures.

{{{
#!Lineno
#!c
unsigned char inline hex_char_val(char ch)
{
  if(ch >= '0' && ch <= '9')
    return ch - '0';
  else
    return ch - 'A' + 10;
}

void inline convert_hex_to_binary(char *hex, unsigned char *out)
{
  int n = 0, i = 0;
  while(hex[n] != 0)
  {
    out[i++] = (hex_char_val(hex[n]) * 16) + hex_char_val(hex[n + 1]);
    if(hex[n + 1] == '\0')
    {
      printf("Invalid hex string\r\n");
      break;
    }
    n += 2;
  }
}

static char hexchar[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

void binary_to_hex_str(unsigned char *in, unsigned char *out, int len)
{
  int n;
  for(n = 0; n < len; n++)
  {
    out[n * 2] = hexchar[((0xF0 & in[n]) >> 4)];
    out[n * 2 + 1] = hexchar[(0x0F & in[n])];
  }
  out[n * 2] = '\0';
}
}}}
''These routines are packaged in [doxygen:hexutil_8cpp-source.html hexutil.cpp]''

For example, an app may access time/date from the mainboard with the following:

{{{
#!c
char* mnbd_dev "/dev/mnbd";
int g_fileMnBd = 0;

int OpenMnBd(void)
{
  /* O_NONBLOCK allows open even with no carrier detect */
  g_fileMnBd = open(mnbd_dev, O_RDWR | O_NOCTTY | O_NONBLOCK);
  if(g_fileMnBd == -1)
  {
    printf("Error opening %s\n", mnbd_dev);
    return -1;
  }
  return 0;
}

void CloseMnBd(0)
{
  close(g_fileMnBd);
  return;
}

int z;
char readbuf![50];
char rcvbuf![50];
int rcvbufpos = 0;
int nread;

OpenMnBd();

write(g_fileMnBd, "S\r", 2); // Request date/time from mainboard

// In main loop of application:
for(;;)
{
  nread = read(g_fileMnBd, &readbuf, sizeof(readbuf) );

  if(nread > 0)
  {
    for(z = 0; z < nread; z++)
    {
      if(readbuf[z] == '\r')
    {

    rcvbuf[rcvbufpos] = '\0';

    // When time/date is received from mainboard set the Linux clock
    if(rcvbuf![0] == 'S')
    {
      struct mnbd_datetime_struct dt;
      convert_hex_to_binary(rcvbuf + 2, (unsigned char *)&dt);
      printf("Date/time from mainboard %d/%d/%d %d:%d:%d\r\n", dt.year, dt.month, dt.day, dt.hour, dt.minute, dt.second);
  
      // Set regular C tm struct to appropriate time values
      struct tm time;
      time.tm_year = dt.year - 1900;
      time.tm_mon = dt.month - 1;
      time.tm_mday = dt.day;
      time.tm_hour = dt.hour;
      time.tm_min = dt.minute;
      time.tm_sec = dt.second;

      time_t tt = mktime(&time);

      stime(&tt);
    }

    rcvbufpos = 0;
  }
  else if(readbuf[z] >= 0x20 && readbuf[z] < 0x7F)
  {
    rcvbuf[rcvbufpos++] = readbuf[z];
  }
}
}}}

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