emc: add a system param :_metric_machine

we read the INI file to check [TRAJ]LINEAR_AXES for 'inch'.
and then set th eparam accordingly.

Useful for remaps to decide how some varibles should be interpreted.

(cherry picked from commit fc01702)

Author: c-morley

src/emc/rs274ngc/interp_namedparams.cc

@@ -744,7 +744,6 @@ int Interp::lookup_named_param(const char *nameBuf,
 	*value = _task;
 	break;
 
-
     default:
 	ERS(_("BUG: lookup_named_param(%s): unhandled index=%fn"),
 	      nameBuf,index);
@@ -781,12 +780,16 @@ int Interp::init_named_parameters()
   const char *pkgversion = PACKAGE_VERSION;  //examples: 2.4.6, 2.5.0~pre
   const char *version_major = "_vmajor";// named_parameter name (use lower case)
   const char *version_minor = "_vminor";// named_parameter name (use lower case)
-  double vmajor=0.0, vminor=0.0;
+  const char *metric_machine = "_metric_machine";// named_parameter name (use lower case)
+  double vmajor=0.0, vminor=0.0, munits = 1.0;
   sscanf(pkgversion, "%lf%lf", &vmajor, &vminor);
 
   init_readonly_param(version_major,vmajor,0);
   init_readonly_param(version_minor,vminor,0);
 
+  munits = inicheck();
+  init_readonly_param(metric_machine,munits,0);
+
   // params tagged with PA_USE_LOOKUP will call the lookup_named_param()
   // method. The value is used as a index for the switch() statement.
 
@@ -906,3 +909,32 @@ int Interp::init_named_parameters()
 
   return INTERP_OK;
 }
+
+double Interp::inicheck()
+{
+    IniFile inifile;
+    const char *filename;
+    const char *inistring;
+    double result = -1.0;
+
+	if ((filename = getenv("INI_FILE_NAME")) == NULL) {
+	    return -1.0;
+    }
+
+    // open it
+    if (inifile.Open(filename) == false) {
+	    return -1.0;
+    }
+
+    if (NULL != (inistring = inifile.Find("LINEAR_UNITS", "TRAJ"))) {
+        if (!strcmp(inistring, "inch")) {
+             result = 0.0;
+        } else {
+            result = 1.0;
+        }
+    }
+    // close it
+    inifile.Close();
+
+    return result;
+}

src/emc/rs274ngc/rs274ngc_interp.hh

@@ -134,6 +134,7 @@ public:
  int add_named_param(const char *nameBuf, int attr = 0);
  int fetch_ini_param( const char *nameBuf, int *status, double *value);
  int fetch_hal_param( const char *nameBuf, int *status, double *value);
+ double inicheck();
 
     // common combination of add_named_param and store_named_param
     // int assign_named_param(const char *nameBuf, int attr = 0, double value = 0.0);