source: git/src/datain.c @ b14f44f

/* datain.c
 * Reads in survey files, dealing with special characters, keywords & data
 * Copyright (C) 1991-2002 Olly Betts
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <limits.h>
#include <stdarg.h>

#include "debug.h"
#include "cavern.h"
#include "filename.h"
#include "message.h"
#include "filelist.h"
#include "netbits.h"
#include "netskel.h"
#include "readval.h"
#include "datain.h"
#include "commands.h"
#include "out.h"
#include "str.h"

#define EPSILON (REAL_EPSILON * 1000)

#define MAX_KEYWORD_LEN 16

#define PRINT_COMMENT 0

#define var(I) (pcs->Var[(I)])

int ch;

typedef enum {CLINO_OMIT, CLINO_READING, CLINO_PLUMB, CLINO_HORIZ} clino_type;

/* Don't explicitly initialise as we can't set the jmp_buf - this has
 * static scope so will be initialised like this anyway */
parse file /* = { NULL, NULL, 0, fFalse, NULL } */ ;

bool f_export_ok;

static filepos fpLineStart;

void
get_pos(filepos *fp)
{
   fp->ch = ch;
   fp->offset = ftell(file.fh);
   if (fp->offset == -1)
      fatalerror_in_file(file.filename, 0, /*Error reading file*/18);
}

void
set_pos(const filepos *fp)
{
   ch = fp->ch;
   if (fseek(file.fh, fp->offset, SEEK_SET) == -1)
      fatalerror_in_file(file.filename, 0, /*Error reading file*/18);
}

static void
push_back(int c)
{
   if (c != EOF && ungetc(c, file.fh) == EOF)
      fatalerror_in_file(file.filename, 0, /*Error reading file*/18);
}

static void
error_list_parent_files(void)
{
   if (!file.reported_where && file.parent) {
      parse *p = file.parent;
      const char *m = msg(/*In file included from*/5);
      size_t len = strlen(m);

      fprintf(STDERR, m);
      m = msg(/*from*/3);

      /* Suppress reporting of full include tree for further errors
       * in this file */
      file.reported_where = fTrue;

      while (p) {
         /* Force re-report of include tree for further errors in
          * parent files */
         p->reported_where = fFalse;
         fprintf(STDERR, " %s:%d", p->filename, p->line);
         p = p->parent;
         if (p) fprintf(STDERR, ",\n%*s", (int)len, m);
      }
      fprintf(STDERR, ":\n");
   }
}

void
compile_error(int en, ...)
{
   va_list ap;
   va_start(ap, en);
   error_list_parent_files();
   v_report(1, file.filename, file.line, en, ap);
   va_end(ap);
}

void
compile_error_token(int en)
{
   char *p = NULL;
   static int len;
   s_zero(&p);
   skipblanks();
   while (!isBlank(ch) && !isEol(ch)) {
      s_catchar(&p, &len, ch);
      nextch();
   }
   compile_error(en, p ? p : "");
   osfree(p);
   skipline();
}

void
compile_warning(int en, ...)
{
   va_list ap;
   va_start(ap, en);
   error_list_parent_files();
   v_report(0, file.filename, file.line, en, ap);
   va_end(ap);
}

/* This function makes a note where to put output files */
static void
using_data_file(const char *fnm)
{
   if (!fnm_output_base) {
      /* was: fnm_output_base = base_from_fnm(fnm); */
      fnm_output_base = baseleaf_from_fnm(fnm);
   } else if (fnm_output_base_is_dir) {
      /* --output pointed to directory so use the leaf basename in that dir */
      char *lf, *p;
      lf = baseleaf_from_fnm(fnm);
      p = use_path(fnm_output_base, lf);
      osfree(lf);
      osfree(fnm_output_base);
      fnm_output_base = p;
      fnm_output_base_is_dir = 0;
   }
}

static void
skipword(void)
{
   while (!isBlank(ch) && !isEol(ch)) nextch();
}

extern void
skipblanks(void)
{
   while (isBlank(ch)) nextch();
}

extern void
skipline(void)
{
   while (!isEol(ch)) nextch();
}

#ifndef NO_PERCENTAGE
static long int filelen;
#endif

static void
process_bol(void)
{
   /* Note start of line for error reporting */
   get_pos(&fpLineStart);

#ifndef NO_PERCENTAGE
   /* print %age of file done */
   if (filelen > 0)
      printf("%d%%\r", (int)(100 * fpLineStart.offset / filelen));
#endif

   nextch();
   skipblanks();
}

static void
process_eol(void)
{
   int eolchar;

   skipblanks();

   if (!isEol(ch)) {
      if (!isComm(ch)) compile_error(/*End of line not blank*/15);
      skipline();
   }

   eolchar = ch;
   file.line++;
   /* skip any different eol characters so we get line counts correct on
    * DOS text files and similar, but don't count several adjacent blank
    * lines as one */
   while (ch != EOF) {
      nextch();
      if (ch == eolchar || !isEol(ch)) {
         push_back(ch);
         break;
      }
   }
}

static bool
process_non_data_line(void)
{
   process_bol();

   if (isData(ch)) return fFalse;

   if (isKeywd(ch)) {
      nextch();
      handle_command();
   }

   process_eol();

   return fTrue;
}

extern void
data_file(const char *pth, const char *fnm)
{
   int begin_lineno_store;
   parse file_store;

   {
      char *filename;
      FILE *fh;
      if (!pth) {
         /* file specified on command line - don't do special translation */
         fh = fopenWithPthAndExt(pth, fnm, EXT_SVX_DATA, "rb", &filename);
      } else {
         fh = fopen_portable(pth, fnm, EXT_SVX_DATA, "rb", &filename);
      }

      if (fh == NULL) {
         compile_error(/*Couldn't open data file `%s'*/24, fnm);
         return;
      }

      file_store = file;
      if (file.fh) file.parent = &file_store;
      file.fh = fh;
      file.filename = filename;
      file.line = 1;
      file.reported_where = fFalse;
   }

   if (fPercent) printf("%s:\n", fnm);

   using_data_file(file.filename);

   begin_lineno_store = pcs->begin_lineno;
   pcs->begin_lineno = 0;

#ifndef NO_PERCENTAGE
   /* Try to find how long the file is...
    * However, under ANSI fseek( ..., SEEK_END) may not be supported */
   filelen = 0;
   if (fPercent) {
      if (fseek(file.fh, 0l, SEEK_END) == 0) {
         filepos fp;
         get_pos(&fp);
         filelen = fp.offset;
      }
      rewind(file.fh); /* reset file ptr to start & clear any error state */
   }
#endif

#ifdef HAVE_SETJMP_H
   /* errors in nested functions can longjmp here */
   if (setjmp(file.jbSkipLine)) {
      process_eol();
   }
#endif

   while (!feof(file.fh) && !ferror(file.fh)) {
      if (!process_non_data_line()) {
         int r;
#ifdef NEW3DFORMAT
         twig *temp = limb;
#endif
         f_export_ok = fFalse;
         switch (pcs->style) {
          case STYLE_NORMAL:
          case STYLE_DIVING:
          case STYLE_CYLPOLAR:
            r = data_normal();
            break;
          case STYLE_CARTESIAN:
            r = data_cartesian();
            break;
          case STYLE_NOSURVEY:
            r = data_nosurvey();
            break;
          case STYLE_IGNORE:
            r = data_ignore();
            break;
          default:
            BUG("bad style");
         }
         /* style function returns 0 => error */
         if (!r) {
#ifdef NEW3DFORMAT
            /* we have just created a very naughty twiglet, and it must be
             * punished */
            osfree(limb);
            limb = temp;
#endif
         }
      }
   }

   /* don't allow *BEGIN at the end of a file, then *EXPORT in the
    * including file */
   f_export_ok = fFalse;

#ifndef NO_PERCENTAGE
   if (fPercent) putnl();
#endif

   if (pcs->begin_lineno) {
      error_in_file(file.filename, pcs->begin_lineno,
                    /*BEGIN with no matching END in this file*/23);
      /* Implicitly close any unclosed BEGINs from this file */
      do {
         settings *pcsParent = pcs->next;
         ASSERT(pcsParent);
         free_settings(pcs);
         pcs = pcsParent;
      } while (pcs->begin_lineno);
   }

   pcs->begin_lineno = begin_lineno_store;

   if (ferror(file.fh))
      fatalerror_in_file(file.filename, 0, /*Error reading file*/18);

   (void)fclose(file.fh);

   file = file_store;

   /* don't free this - it may be pointed to by prefix.file */
   /* osfree(file.filename); */
}

static real
handle_plumb(clino_type *p_ctype)
{
   typedef enum {
      CLINO_NULL=-1, CLINO_UP, CLINO_DOWN, CLINO_LEVEL
   } clino_tok;
   static sztok clino_tab[] = {
      {"D",     CLINO_DOWN},
      {"DOWN",  CLINO_DOWN},
      {"H",     CLINO_LEVEL},
      {"LEVEL", CLINO_LEVEL},
      {"U",     CLINO_UP},
      {"UP",    CLINO_UP},
      {NULL,    CLINO_NULL}
   };
   static real clinos[] = {(real)M_PI_2, (real)(-M_PI_2), (real)0.0};
   clino_tok tok;

   skipblanks();
   if (isalpha(ch)) {
      filepos fp;
      get_pos(&fp);
      get_token();
      tok = match_tok(clino_tab, TABSIZE(clino_tab));
      if (tok != CLINO_NULL) {
         *p_ctype = (clinos[tok] == CLINO_LEVEL ? CLINO_HORIZ : CLINO_PLUMB);
         return clinos[tok];
      }
      set_pos(&fp);
   } else if (isSign(ch)) {
      int chOld = ch;
      nextch();
      if (toupper(ch) == 'V') {
         nextch();
         *p_ctype = CLINO_PLUMB;
         return (!isMinus(chOld) ? M_PI_2 : -M_PI_2);
      }

      if (isOmit(chOld)) {
         *p_ctype = CLINO_OMIT;
         /* no clino reading, so assume 0 with large sd */
         return (real)0.0;
      }
   } else if (isOmit(ch)) {
      /* OMIT char may not be a SIGN char too so we need to check here as
       * well as above... */
      nextch();
      *p_ctype = CLINO_OMIT;
      /* no clino reading, so assume 0 with large sd */
      return (real)0.0;
   }
   return HUGE_REAL;
}

static int
process_normal(prefix *fr, prefix *to, real tape, real comp, real clin,
               real backcomp, real backclin,
               bool fToFirst, clino_type ctype, clino_type backctype)
{
   real dx, dy, dz;
   real vx, vy, vz;
#ifndef NO_COVARIANCES
   real cxy, cyz, czx;
#endif

   bool fNoComp;

   /* adjusted tape is negative -- probably the calibration is wrong */
   if (tape < (real)0.0) {
      /* TRANSLATE different message for topofil? */
      compile_warning(/*Negative adjusted tape reading*/79);
   }

   fNoComp = fTrue;
   if (comp != HUGE_REAL) {
      fNoComp = fFalse;
      comp *= pcs->units[Q_BEARING];
      if (comp < (real)0.0 || comp - M_PI * 2.0 > EPSILON) {
         compile_warning(/*Suspicious compass reading*/59);
      }
   }
   if (backcomp != HUGE_REAL) {
      fNoComp = fFalse;
      backcomp *= pcs->units[Q_BACKBEARING];
      if (backcomp < (real)0.0 || backcomp - M_PI * 2.0 > EPSILON) {
         /* FIXME: different message for BackComp? */
         compile_warning(/*Suspicious compass reading*/59);
      }
   }

   if (ctype == CLINO_READING) {
      real diff_from_abs90;
      clin *= pcs->units[Q_GRADIENT];
      diff_from_abs90 = fabs(clin) - M_PI_2;
      if (diff_from_abs90 > EPSILON) {
         compile_warning(/*Clino reading over 90 degrees (absolute value)*/51);
      } else if (pcs->f90Up && diff_from_abs90 > -EPSILON) {
         ctype = CLINO_PLUMB;
      }
   }

   if (backctype == CLINO_READING) {
      real diff_from_abs90;
      backclin *= pcs->units[Q_BACKGRADIENT];
      diff_from_abs90 = fabs(backclin) - M_PI_2;
      if (diff_from_abs90 > EPSILON) {
         /* FIXME: different message for BackClino? */
         compile_warning(/*Clino reading over 90 degrees (absolute value)*/51);
      } else if (pcs->f90Up && diff_from_abs90 > -EPSILON) {
         backctype = CLINO_PLUMB;
      }
   }

   if (ctype != CLINO_OMIT && backctype != CLINO_OMIT && ctype != backctype) {
      compile_error(/*Clino and BackClino readings must be of the same type*/84);
      skipline();
      return 0;
   }

   if (ctype == CLINO_PLUMB || backctype == CLINO_PLUMB) {
      /* plumbed */
      if (!fNoComp) {
         /* FIXME: Different message for BackCompass */
         compile_warning(/*Compass reading given on plumbed leg*/21);
      }

      dx = dy = (real)0.0;
      if (ctype != CLINO_OMIT) {
         if (backctype != CLINO_OMIT && (clin > 0) == (backclin > 0)) {
            /* We've got two UPs or two DOWNs - FIXME: not ideal message */
            compile_error(/*Clino and BackClino readings must be of the same type*/84);
            skipline();
            return 0;
         }
         dz = (clin > (real)0.0) ? tape : -tape;
      } else {
         dz = (backclin < (real)0.0) ? tape : -tape;
      }
      vx = vy = var(Q_POS) / 3.0 + dz * dz * var(Q_PLUMB);
      vz = var(Q_POS) / 3.0 + var(Q_LENGTH);
#ifndef NO_COVARIANCES
      /* Correct values - no covariances in this case! */
      cxy = cyz = czx = (real)0.0;
#endif
   } else {
      /* Each of ctype and backctype are either CLINO_READING/CLINO_HORIZ
       * or CLINO_OMIT */
      /* clino */
      real L2, cosG, LcosG, cosG2, sinB, cosB, dx2, dy2, dz2, v, V;
      if (fNoComp) {
         compile_error(/*Compass reading may not be omitted except on plumbed legs*/14);
         skipline();
         return 0;
      }
      if (tape == (real)0.0) {
         dx = dy = dz = (real)0.0;
         vx = vy = vz = (real)(var(Q_POS) / 3.0); /* Position error only */
#ifndef NO_COVARIANCES
         cxy = cyz = czx = (real)0.0;
#endif
#if DEBUG_DATAIN_1
         printf("Zero length leg: vx = %f, vy = %f, vz = %f\n", vx, vy, vz);
#endif
      } else {
         real sinGcosG;
         real var_comp = var(Q_BEARING);
         /* take into account variance in LEVEL case */
         real var_clin = var(Q_LEVEL);
         if (comp != HUGE_REAL) {
            comp = (comp - pcs->z[Q_BEARING]) * pcs->sc[Q_BEARING];
            comp -= pcs->z[Q_DECLINATION];
         }
         if (backcomp != HUGE_REAL) {
            backcomp = (backcomp - pcs->z[Q_BACKBEARING])
                    * pcs->sc[Q_BACKBEARING];
            backcomp -= pcs->z[Q_DECLINATION];
            backcomp -= M_PI;
            if (comp != HUGE_REAL) {
               real diff = comp - backcomp;
               diff -= floor((diff + M_PI) / (2 * M_PI)) * 2 * M_PI;
               if (sqrd(diff / 3.0) > var_comp + var(Q_BACKBEARING)) {
                  /* fore and back readings differ by more than 3 sds */
                  /* FIXME: complain */
               }
               comp = (comp / var_comp + backcomp / var(Q_BACKBEARING));
               var_comp = (var_comp + var(Q_BACKBEARING)) / 4;
               comp *= var_comp;
            } else {
               comp = backcomp;
               var_comp = var(Q_BACKBEARING);
            }
         }
         /* ctype != CLINO_READING is LEVEL case */
         if (ctype == CLINO_READING) {
            clin = (clin - pcs->z[Q_GRADIENT]) * pcs->sc[Q_GRADIENT];
            var_clin = var(Q_GRADIENT);
         }
         if (backctype == CLINO_READING) {
            backclin = (backclin - pcs->z[Q_BACKGRADIENT])
               * pcs->sc[Q_BACKGRADIENT];
            if (ctype == CLINO_READING) {
               if (sqrd((clin + backclin) / 3.0) >
                     var_clin + var(Q_BACKGRADIENT)) {
                  /* fore and back readings differ by more than 3 sds */
                  /* FIXME: complain */
               }
               clin = (clin / var_clin - backclin / var(Q_BACKGRADIENT));
               var_clin = (var_clin + var(Q_BACKGRADIENT)) / 4;
               clin *= var_clin;
            } else {
               clin = -backclin;
               var_clin = var(Q_BACKGRADIENT);
            }
         }

#if DEBUG_DATAIN
         printf("    %4.2f %4.2f %4.2f\n", tape, comp, clin);
#endif
         cosG = cos(clin);
         LcosG = tape * cosG;
         sinB = sin(comp);
         cosB = cos(comp);
#if DEBUG_DATAIN_1
         printf("sinB = %f, cosG = %f, LcosG = %f\n", sinB, cosG, LcosG);
#endif
         dx = LcosG * sinB;
         dy = LcosG * cosB;
         dz = tape * sin(clin);
/*      printf("%.2f\n",clin); */
#if DEBUG_DATAIN_1
         printf("dx = %f\ndy = %f\ndz = %f\n", dx, dy, dz);
#endif
         dx2 = dx * dx;
         L2 = tape * tape;
         V = var(Q_LENGTH) / L2;
         dy2 = dy * dy;
         cosG2 = cosG * cosG;
         sinGcosG = sin(clin) * cosG;
         dz2 = dz * dz;
         v = dz2 * var_clin;
#ifdef NO_COVARIANCES
         vx = (var(Q_POS) / 3.0 + dx2 * V + dy2 * var_comp +
               (.5 + sinB * sinB * cosG2) * v);
         vy = (var(Q_POS) / 3.0 + dy2 * V + dx2 * var_comp +
               (.5 + cosB * cosB * cosG2) * v);
         if (ctype == CLINO_OMIT && backctype == CLINO_OMIT) {
            /* if no clino, assume sd=tape/sqrt(10) so 3sds = .95*tape */
            vz = var(Q_POS) / 3.0 + L2 * (real)0.1;
         } else {
            vz = var(Q_POS) / 3.0 + dz2 * V + L2 * cosG2 * var_clin;
         }
         /* for Surveyor87 errors: vx=vy=vz=var(Q_POS)/3.0; */
#else
         vx = var(Q_POS) / 3.0 + dx2 * V + dy2 * var_comp +
            (sinB * sinB * v);
         vy = var(Q_POS) / 3.0 + dy2 * V + dx2 * var_comp +
            (cosB * cosB * v);
         if (ctype == CLINO_OMIT && backctype == CLINO_OMIT) {
            /* if no clino, assume sd=tape/sqrt(10) so 3sds = .95*tape */
            vz = var(Q_POS) / 3.0 + L2 * (real)0.1;
         } else {
            vz = var(Q_POS) / 3.0 + dz2 * V + L2 * cosG2 * var_clin;
         }
         /* usual covariance formulae are fine in no clino case since
          * dz = 0 so value of var_clin is ignored */
         cxy = sinB * cosB * (var(Q_LENGTH) * cosG2 + var_clin * dz2)
               - var_comp * dx * dy;
         czx = var(Q_LENGTH) * sinB * sinGcosG - var_clin * dx * dz;
         cyz = var(Q_LENGTH) * cosB * sinGcosG - var_clin * dy * dz;
#if 0
         printf("vx = %6.3f, vy = %6.3f, vz = %6.3f\n", vx, vy, vz);
         printf("cxy = %6.3f, cyz = %6.3f, czx = %6.3f\n", cxy, cyz, czx);
#endif
#endif
#if DEBUG_DATAIN_1
         printf("In DATAIN.C, vx = %f, vy = %f, vz = %f\n", vx, vy, vz);
#endif
      }
   }
#if DEBUG_DATAIN_1
   printf("Just before addleg, vx = %f\n", vx);
#endif
   /*printf("dx,dy,dz = %.2f %.2f %.2f\n\n", dx, dy, dz);*/
   addlegbyname(fr, to, fToFirst, dx, dy, dz, vx, vy, vz
#ifndef NO_COVARIANCES
                , cyz, czx, cxy
#endif
                );

#ifdef NEW3DFORMAT
   if (fUseNewFormat) {
      /* new twiglet and insert into twig tree */
      twig *twiglet = osnew(twig);
      twiglet->from = fr;
      twiglet->to = to;
      twiglet->down = twiglet->right = NULL;
      twiglet->source = twiglet->drawings
        = twiglet->date = twiglet->instruments = twiglet->tape = NULL;
      twiglet->up = limb->up;
      limb->right = twiglet;
      limb = twiglet;

      /* record pre-fettling deltas */
      twiglet->delta[0] = dx;
      twiglet->delta[1] = dy;
      twiglet->delta[2] = dz;
   }
#endif
   return 1;
}

static int
process_diving(prefix *fr, prefix *to, real tape, real comp, real backcomp,
               real frdepth, real todepth, bool fToFirst, bool fDepthChange)
{
   real dx, dy, dz;
   real vx, vy, vz;
#ifndef NO_COVARIANCES
   real cxy = 0, cyz = 0, czx = 0;
#endif

   if (comp != HUGE_REAL) {
      comp *= pcs->units[Q_BEARING];
      if (comp < (real)0.0 || comp - M_PI * 2.0 > EPSILON) {
         compile_warning(/*Suspicious compass reading*/59);
      }
   }
   if (backcomp != HUGE_REAL) {
      backcomp *= pcs->units[Q_BACKBEARING];
      if (backcomp < (real)0.0 || backcomp - M_PI * 2.0 > EPSILON) {
         /* FIXME: different message for BackComp? */
         compile_warning(/*Suspicious compass reading*/59);
      }
   }

   /* depth gauge readings increase upwards with default calibration */
   if (fDepthChange) {
      ASSERT(frdepth == 0.0);
      dz = (todepth * pcs->units[Q_DEPTH] - pcs->z[Q_DEPTH]) * pcs->sc[Q_DEPTH];
   } else {
      dz = (todepth - frdepth) * pcs->units[Q_DEPTH] * pcs->sc[Q_DEPTH];
   }

   /* adjusted tape is negative -- probably the calibration is wrong */
   if (tape < (real)0.0) {
      compile_warning(/*Negative adjusted tape reading*/79);
   }

   /* check if tape is less than depth change */
   if (tape < fabs(dz)) {
      /* FIXME: allow margin of error based on variances? */
      compile_warning(/*Tape reading is less than change in depth*/62);
   }

   if (tape == (real)0.0 && dz == 0.0) {
      dx = dy = dz = (real)0.0;
      vx = vy = vz = (real)(var(Q_POS) / 3.0); /* Position error only */
   } else if (comp == HUGE_REAL && backcomp == HUGE_REAL) {
      /* plumb */
      dx = dy = (real)0.0;
      if (dz < 0) tape = -tape;
      dz = (dz * var(Q_LENGTH) + tape * 2 * var(Q_DEPTH))
         / (var(Q_LENGTH) * 2 * var(Q_DEPTH));
      vx = vy = var(Q_POS) / 3.0 + dz * dz * var(Q_PLUMB);
      vz = var(Q_POS) / 3.0 + var(Q_LENGTH) * 2 * var(Q_DEPTH)
                              / (var(Q_LENGTH) + var(Q_DEPTH));
   } else {
      real L2, sinB, cosB, dz2, D2;
      real var_comp = var(Q_BEARING);
      if (comp != HUGE_REAL) {
         comp = (comp - pcs->z[Q_BEARING]) * pcs->sc[Q_BEARING];
         comp -= pcs->z[Q_DECLINATION];
      }
      if (backcomp != HUGE_REAL) {
         backcomp = (backcomp - pcs->z[Q_BACKBEARING]) * pcs->sc[Q_BACKBEARING];
         backcomp -= pcs->z[Q_DECLINATION];
         backcomp -= M_PI;
      }
      if (comp != HUGE_REAL) {
         if (backcomp != HUGE_REAL) {
            real diff = comp - backcomp;
            diff -= floor((diff + M_PI) / (2 * M_PI)) * 2 * M_PI;
            if (sqrd(diff / 3.0) > var_comp + var(Q_BACKBEARING)) {
               /* fore and back readings differ by more than 3 sds */
               /* FIXME: complain */
            }
            comp = (comp / var_comp + backcomp / var(Q_BACKBEARING));
            var_comp = (var_comp + var(Q_BACKBEARING)) / 4;
            comp *= var_comp;
         }
      } else {
         comp = backcomp;
         var_comp = var(Q_BACKBEARING);
      }
            
      sinB = sin(comp);
      cosB = cos(comp);
      L2 = tape * tape;
      dz2 = dz * dz;
      D2 = L2 - dz2;
      if (D2 <= (real)0.0) {
         real vsum = var(Q_LENGTH) + 2 * var(Q_DEPTH);
         dx = dy = (real)0.0;
         vx = vy = var(Q_POS) / 3.0;
         vz = var(Q_POS) / 3.0 + var(Q_LENGTH) * 2 * var(Q_DEPTH) / vsum;
         if (dz > 0) {
            dz = (dz * var(Q_LENGTH) + tape * 2 * var(Q_DEPTH)) / vsum;
         } else {
            dz = (dz * var(Q_LENGTH) - tape * 2 * var(Q_DEPTH)) / vsum;
         }
      } else {
         real D = sqrt(D2);
         real F = var(Q_LENGTH) * L2 + 2 * var(Q_DEPTH) * D2;
         dx = D * sinB;
         dy = D * cosB;

         vx = var(Q_POS) / 3.0 +
            sinB * sinB * F / D2 + var_comp * dy * dy;
         vy = var(Q_POS) / 3.0 +
            cosB * cosB * F / D2 + var_comp * dx * dx;
         vz = var(Q_POS) / 3.0 + 2 * var(Q_DEPTH);

#ifndef NO_COVARIANCES
         cxy = sinB * cosB * (F / D2 + var_comp * D2);
         cyz = -2 * var(Q_DEPTH) * dy / D;
         czx = -2 * var(Q_DEPTH) * dx / D;
#endif
      }
   }
   addlegbyname(fr, to, fToFirst, dx, dy, dz, vx, vy, vz
#ifndef NO_COVARIANCES
                , cxy, cyz, czx
#endif
                );
#ifdef NEW3DFORMAT
   if (fUseNewFormat) {
      /*new twiglet and insert into twig tree*/
      twig *twiglet = osnew(twig);
      twiglet->from = fr;
      twiglet->to = to;
      twiglet->down = twiglet->right = NULL;
      twiglet->source = twiglet->drawings
        = twiglet->date = twiglet->instruments = twiglet->tape = NULL;
      twiglet->up = limb->up;
      limb->right = twiglet;
      limb = twiglet;

      /* record pre-fettling deltas */
      twiglet->delta[0] = dx;
      twiglet->delta[1] = dy;
      twiglet->delta[2] = dz;
   }
#endif

   return 1;
}

static int
process_cartesian(prefix *fr, prefix *to, real dx, real dy, real dz,
                  bool fToFirst)
{
   dx = (dx * pcs->units[Q_DX] - pcs->z[Q_DX]) * pcs->sc[Q_DX];
   dy = (dy * pcs->units[Q_DY] - pcs->z[Q_DY]) * pcs->sc[Q_DY];
   dz = (dz * pcs->units[Q_DZ] - pcs->z[Q_DZ]) * pcs->sc[Q_DZ];

   addlegbyname(fr, to, fToFirst, dx, dy, dz, var(Q_DX), var(Q_DY), var(Q_DZ)
#ifndef NO_COVARIANCES
                , 0, 0, 0
#endif
                );

#ifdef NEW3DFORMAT
   if (fUseNewFormat) {
      /* new twiglet and insert into twig tree */
      twig *twiglet = osnew(twig);
      twiglet->from = fr;
      twiglet->to = to;
      twiglet->down = twiglet->right = NULL;
      twiglet->source = twiglet->drawings
        = twiglet->date = twiglet->instruments = twiglet->tape = NULL;
      twiglet->up = limb->up;
      limb->right = twiglet;
      limb = twiglet;

      /* record pre-fettling deltas */
      twiglet->delta[0] = dx;
      twiglet->delta[1] = dy;
      twiglet->delta[2] = dz;
   }
#endif

   return 1;
}

extern int
data_cartesian(void)
{
   prefix *fr = NULL, *to = NULL;
   real dx = 0, dy = 0, dz = 0;

   bool fMulti = fFalse;

   reading first_stn = End;

   reading *ordering;

   again:

   for (ordering = pcs->ordering ; ; ordering++) {
      skipblanks();
      switch (*ordering) {
       case Fr:
          fr = read_prefix_stn(fFalse, fTrue);
          if (first_stn == End) first_stn = Fr;
          break;
       case To:
          to = read_prefix_stn(fFalse, fTrue);
          if (first_stn == End) first_stn = To;
          break;
       case Station:
          fr = to;
          to = read_prefix_stn(fFalse, fFalse);
          first_stn = To;
          break;
       case Dx: dx = read_numeric(fFalse); break;
       case Dy: dy = read_numeric(fFalse); break;
       case Dz: dz = read_numeric(fFalse); break;
       case Ignore:
         skipword(); break;
       case IgnoreAllAndNewLine:
         skipline();
         /* fall through */
       case Newline:
         if (fr != NULL) {
            int r;
            r = process_cartesian(fr, to, dx, dy, dz, first_stn == To);
            if (!r) skipline();
         }
         fMulti = fTrue;
         while (1) {
            process_eol();
            process_bol();
            if (isData(ch)) break;
            if (!isComm(ch)) {
               push_back(ch);
               return 1;
            }
         }
         break;
       case IgnoreAll:
         skipline();
         /* fall through */
       case End:
         if (!fMulti) {
            int r = process_cartesian(fr, to, dx, dy, dz, first_stn == To);
            process_eol();
            return r;
         }
         do {
            process_eol();
            process_bol();
         } while (isComm(ch));
         goto again;
       default: BUG("Unknown reading in ordering");
      }
   }
}

static int
process_cylpolar(prefix *fr, prefix *to, real tape, real comp, real backcomp,
                 real frdepth, real todepth, bool fToFirst, bool fDepthChange)
{
   real dx, dy, dz;
   real vx, vy, vz;
#ifndef NO_COVARIANCES
   real cxy = 0;
#endif

   if (comp != HUGE_REAL) {
      comp *= pcs->units[Q_BEARING];
      if (comp < (real)0.0 || comp - M_PI * 2.0 > EPSILON) {
         compile_warning(/*Suspicious compass reading*/59);
      }
   }
   if (backcomp != HUGE_REAL) {
      backcomp *= pcs->units[Q_BACKBEARING];
      if (backcomp < (real)0.0 || backcomp - M_PI * 2.0 > EPSILON) {
         /* FIXME: different message for BackComp? */
         compile_warning(/*Suspicious compass reading*/59);
      }
   }

   /* depth gauge readings increase upwards with default calibration */
   if (fDepthChange) {
      ASSERT(frdepth == 0.0);
      dz = (todepth * pcs->units[Q_DEPTH] - pcs->z[Q_DEPTH]) * pcs->sc[Q_DEPTH];
   } else {
      dz = (todepth - frdepth) * pcs->units[Q_DEPTH] * pcs->sc[Q_DEPTH];
   }

   /* adjusted tape is negative -- probably the calibration is wrong */
   if (tape < (real)0.0) {
      compile_warning(/*Negative adjusted tape reading*/79);
   }

   if (comp == HUGE_REAL && backcomp == HUGE_REAL) {
      /* plumb */
      dx = dy = (real)0.0;
      vx = vy = var(Q_POS) / 3.0 + dz * dz * var(Q_PLUMB);
      vz = var(Q_POS) / 3.0 + 2 * var(Q_DEPTH);
   } else {
      real sinB, cosB;
      real var_comp = var(Q_BEARING);
      if (comp != HUGE_REAL) {
         comp = (comp - pcs->z[Q_BEARING]) * pcs->sc[Q_BEARING];
         comp -= pcs->z[Q_DECLINATION];
      }
      if (backcomp != HUGE_REAL) {
         backcomp = (backcomp - pcs->z[Q_BACKBEARING]) * pcs->sc[Q_BACKBEARING];
         backcomp -= pcs->z[Q_DECLINATION];
         backcomp -= M_PI;
      }
      if (comp != HUGE_REAL) {
         if (backcomp != HUGE_REAL) {
            real diff = comp - backcomp;
            diff -= floor((diff + M_PI) / (2 * M_PI)) * 2 * M_PI;
            if (sqrd(diff / 3.0) > var_comp + var(Q_BACKBEARING)) {
               /* fore and back readings differ by more than 3 sds */
               /* FIXME: complain */
            }
            comp = (comp / var_comp + backcomp / var(Q_BACKBEARING));
            var_comp = (var_comp + var(Q_BACKBEARING)) / 4;
            comp *= var_comp;
         }
      } else {
         comp = backcomp;
         var_comp = var(Q_BACKBEARING);
      }

      sinB = sin(comp);
      cosB = cos(comp);

      dx = tape * sinB;
      dy = tape * cosB;

      vx = var(Q_POS) / 3.0 +
         var(Q_LENGTH) * sinB * sinB + var_comp * dy * dy;
      vy = var(Q_POS) / 3.0 +
         var(Q_LENGTH) * cosB * cosB + var_comp * dx * dx;
      vz = var(Q_POS) / 3.0 + 2 * var(Q_DEPTH);

#ifndef NO_COVARIANCES
      cxy = (var(Q_LENGTH) - var_comp * tape * tape) * sinB * cosB;
#endif
   }
   addlegbyname(fr, to, fToFirst, dx, dy, dz, vx, vy, vz
#ifndef NO_COVARIANCES
                , cxy, 0, 0
#endif
                );
#ifdef NEW3DFORMAT
   if (fUseNewFormat) {
      /*new twiglet and insert into twig tree*/
      twig *twiglet = osnew(twig);
      twiglet->from = fr;
      twiglet->to = to;
      twiglet->down = twiglet->right = NULL;
      twiglet->source = twiglet->drawings
        = twiglet->date = twiglet->instruments = twiglet->tape = NULL;
      twiglet->up = limb->up;
      limb->right = twiglet;
      limb = twiglet;

      /* record pre-fettling deltas */
      twiglet->delta[0] = dx;
      twiglet->delta[1] = dy;
      twiglet->delta[2] = dz;
   }
#endif

   return 1;
}

/* Process tape/compass/clino, diving, and cylpolar styles of survey data
 * Also handles topofil (fromcount/tocount or count) in place of tape */
extern int
data_normal(void)
{
   prefix *fr = NULL, *to = NULL;
   reading first_stn = End;

   real tape = 0, comp = HUGE_VAL, backcomp = HUGE_VAL, frcount = 0, tocount = 0;
   real clin, backclin;
   real frdepth = 0, todepth = 0;

   bool fTopofil = fFalse, fMulti = fFalse;
   bool fRev;
   bool ctype, backctype;
   bool fDepthChange;

   reading *ordering;

   again:

   fRev = fFalse;
   ctype = backctype = CLINO_OMIT;
   fDepthChange = fFalse;

   /* ordering may omit clino reading, so set up default here */
   /* this is also used if clino reading is the omit character */
   backclin = clin = (real)0.0;

   for (ordering = pcs->ordering; ; ordering++) {
      skipblanks();
      switch (*ordering) {
       case Fr:
          fr = read_prefix_stn(fFalse, fTrue);
          if (first_stn == End) first_stn = Fr;
          break;
       case To:
          to = read_prefix_stn(fFalse, fTrue);
          if (first_stn == End) first_stn = To;
          break;
       case Station:
          fr = to;
          to = read_prefix_stn(fFalse, fFalse);
          first_stn = To;
          break;
       case Dir:
          switch(toupper(ch)) {
           case 'F':
             break;
           case 'B':
             fRev = fTrue;
             break;
           default:
             compile_error(/*Found `%c', expecting `F' or `B'*/131, ch);
             skipline();
             process_eol();
             return 0;
          }
          break;
       case Tape:
          tape = read_numeric(fFalse);
          if (tape < (real)0.0) compile_warning(/*Negative tape reading*/60);
          break;
       case Count:
          frcount = tocount;
          tocount = read_numeric(fFalse);
          break;
       case FrCount:
          frcount = read_numeric(fFalse);
          break;
       case ToCount:
          tocount = read_numeric(fFalse);
          fTopofil = fTrue;
          break;
       case Comp:
          comp = read_numeric_or_omit();
          break;
       case BackComp:
          backcomp = read_numeric_or_omit();
          break;
       case Clino:
          clin = read_numeric(fTrue);
          if (clin == HUGE_REAL) {
             clin = handle_plumb(&ctype);
             if (clin != HUGE_REAL) break;
             compile_error_token(/*Expecting numeric field, found `%s'*/9);
             process_eol();
             return 0;
          }
          ctype = CLINO_READING;
          break;
       case BackClino:
          backclin = read_numeric(fTrue);
          if (backclin == HUGE_REAL) {
             backclin = handle_plumb(&backctype);
             if (backclin != HUGE_REAL) break;
             compile_error_token(/*Expecting numeric field, found `%s'*/9);
             process_eol();
             return 0;
          }
          backctype = CLINO_READING;
          break;
       case FrDepth:
          frdepth = read_numeric(fFalse);
          break;
       case ToDepth:
          todepth = read_numeric(fFalse);
          break;
       case Depth:
          frdepth = todepth;
          todepth = read_numeric(fFalse);
          break;
       case DepthChange:
          fDepthChange = fTrue;
          frdepth = 0;
          todepth = read_numeric(fFalse);
          break;
       case Ignore:
          skipword();
          break;
       case IgnoreAllAndNewLine:
          skipline();
          /* fall through */
       case Newline:
          if (fr != NULL) {
             int r;
             if (fRev) {
                prefix *t = fr;
                fr = to;
                to = t;
             }
             if (fTopofil) tape = tocount - frcount;
             /* Note: frdepth == todepth test works regardless of fDepthChange
              * (frdepth always zero, todepth is change of depth) and also
              * works for STYLE_NORMAL (both remain 0) */
             if (pcs->f0Eq && tape == (real)0.0 && frdepth == todepth) {
                process_equate(fr, to);
                goto inferred_equate;
             }
             if (fTopofil) {
                tape *= pcs->units[Q_COUNT] * pcs->sc[Q_COUNT];
             } else {
                tape *= pcs->units[Q_LENGTH];
                tape = (tape - pcs->z[Q_LENGTH]) * pcs->sc[Q_LENGTH];
             }
             switch (pcs->style) {
              case STYLE_NORMAL:
                r = process_normal(fr, to, tape, comp, clin,
                                   backcomp, backclin,
                                   (first_stn == To) ^ fRev, ctype, backctype);
                break;
              case STYLE_DIVING:
                r = process_diving(fr, to, tape, comp, backcomp,
                                   frdepth, todepth,
                                   (first_stn == To) ^ fRev, fDepthChange);
                break;
              case STYLE_CYLPOLAR:
                r = process_cylpolar(fr, to, tape, comp, backcomp,
                                     frdepth, todepth,
                                     (first_stn == To) ^ fRev, fDepthChange);
                break;
              default:
                BUG("bad style");
             }
             if (!r) skipline();
          }
          inferred_equate:
          fMulti = fTrue;
          while (1) {
              process_eol();
              process_bol();
              if (isData(ch)) break;
              if (!isComm(ch)) {
                 push_back(ch);
                 return 1;
              }
          }
          break;
       case IgnoreAll:
          skipline();
          /* fall through */
       case End:
          if (!fMulti) {
             int r;
             if (fRev) {
                prefix *t = fr;
                fr = to;
                to = t;
             }
             if (fTopofil) tape = tocount - frcount;
             /* Note: frdepth == todepth test works regardless of fDepthChange
              * (frdepth always zero, todepth is change of depth) and also
              * works for STYLE_NORMAL (both remain 0) */
             if (pcs->f0Eq && tape == (real)0.0 && frdepth == todepth) {
                process_equate(fr, to);
                process_eol();
                return 1;
             }
             if (fTopofil) {
                tape *= pcs->units[Q_COUNT] * pcs->sc[Q_COUNT];
             } else {
                tape *= pcs->units[Q_LENGTH];
                tape = (tape - pcs->z[Q_LENGTH]) * pcs->sc[Q_LENGTH];
             }
             switch (pcs->style) {
              case STYLE_NORMAL:
                r = process_normal(fr, to, tape, comp, clin,
                                   backcomp, backclin,
                                   (first_stn == To) ^ fRev, ctype, backctype);
                break;
              case STYLE_DIVING:
                r = process_diving(fr, to, tape, comp, backcomp,
                                   frdepth, todepth,
                                   (first_stn == To) ^ fRev, fDepthChange);
                break;
              case STYLE_CYLPOLAR:
                r = process_cylpolar(fr, to, tape, comp, backcomp,
                                     frdepth, todepth,
                                     (first_stn == To) ^ fRev, fDepthChange);
                break;
              default:
                BUG("bad style");
             }
             process_eol();
             return r;
          }
          do {
             process_eol();
             process_bol();
          } while (isComm(ch));
          goto again;
       default:
          BUG("Unknown reading in ordering");
      }
   }
}

static int
process_nosurvey(prefix *fr, prefix *to, bool fToFirst)
{
   nosurveylink *link;
   int shape;

#ifdef NEW3DFORMAT
   if (fUseNewFormat) {
      /* new twiglet and insert into twig tree */
      twig *twiglet = osnew(twig);
      twiglet->from = fr;
      twiglet->to = to;
      twiglet->down = twiglet->right = NULL;
      twiglet->source = twiglet->drawings
        = twiglet->date = twiglet->instruments = twiglet->tape = NULL;
      twiglet->up = limb->up;
      limb->right = twiglet;
      limb = twiglet;
      /* delta is only used to calculate error - pass zero and cope
       * elsewhere */
      twiglet->delta[0] = twiglet->delta[1] = twiglet->delta[2] = 0;
   }
#endif

   /* Suppress "unused fixed point" warnings for these stations
    * We do this if it's a 0 or 1 node - 1 node might be an sdfix
    */
   shape = fr->shape;
   if (shape == 0 || shape == 1) fr->shape = -1 - shape;
   shape = to->shape;
   if (shape == 0 || shape == 1) to->shape = -1 - shape;

   /* add to linked list which is dealt with after network is solved */
   link = osnew(nosurveylink);
   if (fToFirst) {
      link->to = StnFromPfx(to);
      link->fr = StnFromPfx(fr);
   } else {
      link->fr = StnFromPfx(fr);
      link->to = StnFromPfx(to);
   }
   link->flags = pcs->flags;
   link->next = nosurveyhead;
   nosurveyhead = link;
   return 1;
}

extern int
data_nosurvey(void)
{
   prefix *fr = NULL, *to = NULL;

   bool fMulti = fFalse;

   reading first_stn = End;

   reading *ordering;

   again:

   for (ordering = pcs->ordering ; ; ordering++) {
      skipblanks();
      switch (*ordering) {
       case Fr:
          fr = read_prefix_stn(fFalse, fTrue);
          if (first_stn == End) first_stn = Fr;
          break;
       case To:
          to = read_prefix_stn(fFalse, fTrue);
          if (first_stn == End) first_stn = To;
          break;
       case Station:
          fr = to;
          to = read_prefix_stn(fFalse, fFalse);
          first_stn = To;
          break;
       case Ignore:
         skipword(); break;
       case IgnoreAllAndNewLine:
         skipline();
         /* fall through */
       case Newline:
         if (fr != NULL) {
            int r;
            r = process_nosurvey(fr, to, first_stn == To);
            if (!r) skipline();
         }
         if (ordering[1] == End) {
            do {
               process_eol();
               process_bol();
            } while (isComm(ch));
            if (!isData(ch)) {
               push_back(ch);
               return 1;
            }
            goto again;
         }
         fMulti = fTrue;
         while (1) {
            process_eol();
            process_bol();
            if (isData(ch)) break;
            if (!isComm(ch)) {
               push_back(ch);
               return 1;
            }
         }
         break;
       case IgnoreAll:
         skipline();
         /* fall through */
       case End:
         if (!fMulti) {
            int r = process_nosurvey(fr, to, first_stn == To);
            process_eol();
            return r;
         }
         do {
            process_eol();
            process_bol();
         } while (isComm(ch));
         goto again;
       default: BUG("Unknown reading in ordering");
      }
   }
}

/* totally ignore a line of survey data */
extern int
data_ignore(void)
{
   skipline();
   process_eol();
   return 1;
}