/* showg.c  version 2.1; B D McKay, August 2017.
   Formerly called readg.c.
 
   This is a stand-alone edition of listg.c that does not
   need nauty or any other files.  Use listg in preference
   if you have installed it.  */

#define USAGE "showg [-p#:#l#o#Ftq] [-a|-A|-c|-d|-e] [infile [outfile]]"

#define HELPTEXT \
" Write graphs in human-readable format.\n\
\n\
   infile is the input file in graph6, sparse6 or digraph6 format\n\
     This program does not support incremental sparse6 files; use listg.\n\
   outfile is the output file\n\
   Defaults are standard input and standard output.\n\
\n\
    -p#, -p#:#, -p#-# : only display one graph or a sequence of\n\
          graphs.  The first graph is number 1.  A second number\n\
          which is empty or zero means infinity.\n\
\n\
    -a  : write the adjacency matrix\n\
    -A  : same as -a with a space between entries\n\
    -d  : write output to satisfy dreadnaut\n\
    -c  : write compact dreadnaut form with minimal line-breaks\n\
    -e  : write a list of edges, preceded by the order and the\n\
          number of edges\n\
\n\
    -o# : specify number of first vertex (default is 0)\n\
    -t  : write upper triangle only (affects -a, -A, -d and default)\n\
    -F  : write a form-feed after each graph except the last\n\
    -l# : specify screen width limit (default 78, 0 means no limit)\n\
          This is not currently implemented with -a or -A.\n\
    -q  : suppress auxiliary output\n\
\n\
    -a, -A, -c, -d and -e are incompatible.\n"

/*
 Version 1.1: Fixed sparse6 input for powers of 2.  May 9, 1998.
 Version 1.3: Declared errno according to ISO C.  August 22, 1998.
 Version 1.4: Change name of getline() so that broken compilers
                which define the GNU function without being asked
                don't cause a conflict.   June 16, 2006.
 Version 1.5: Use function prototypes.  Avoid errno.  Sep 19, 2007.
 Version 1.6: Very minor tweaks.  Hope you all have string.h. Sep 6, 2009.
 Version 1.7: Make it work for n=0. Sep 18, 2013.
 Version 2.0: Support digraph6 format.
 Version 2.1: Fix digraph6 format and remove limit of 200K or so vertices.
*/

/*************************************************************************/

#include <stdio.h>
#include <string.h>

/* gtools.h : General header for gtools programs. */

#ifndef MAXN 
#define MAXN  0
#endif

#define BIAS6 63
#define MAXBYTE 126
#define SMALLN 62
#define SMALLISHN 258047
#define TOPBIT6 32
#define C6MASK 63

#define SIZELEN(n) ((n)<=SMALLN?1:((n)<=SMALLISHN?4:8))
        /* length of size code in bytes */
#define G6BODYLEN(n) \
   (((size_t)(n)/12)*((size_t)(n)-1) + (((size_t)(n)%12)*((size_t)(n)-1)+11)/12)
#define G6LEN(n) (SIZELEN(n) + G6BODYLEN(n))
  /* exact graph6 string length excluding \n\0
     This twisted expression works up to n=227023 in 32-bit arithmetic
     and for larger n if size_t has 64 bits.  */
#define D6BODYLEN(n) \
   ((n)*(size_t)((n)/6) + (((n)*(size_t)((n)%6)+5)/6))
#define D6LEN(n) (1 + SIZELEN(n) + D6BODYLEN(n))
  /* exact digraph6 string length excluding \n\0
     This twisted expression works up to n=160529 in 32-bit arithmetic
     and for larger n if size_t has 64 bits.  */

#define B(i) (1 << ((i)-1))
#define M(i) ((1 << (i))-1)

/* Remove errno: too hard to get portable without configuration
 * #if defined(__unix) || defined(__unix__) || defined(unix) || \
    defined(__ppc__)
#include <errno.h>
#else
int errno = 0;
#endif
#define ABORT(msg) {if (errno != 0) perror(msg); exit(1);}
*/

/* extern long ftell(FILE*);   Should be in stdio.h  */

#define GRAPH6_HEADER ">>graph6<<"
#define SPARSE6_HEADER ">>sparse6<<"
#define DIGRAPH6_HEADER ">>digraph6<<"

#define GRAPH6         1
#define SPARSE6        2
#define DIGRAPH6       4
#define UNKNOWN_TYPE 256
#define HAS_HEADER   512

#define ARG_OK 0
#define ARG_MISSING 1
#define ARG_TOOBIG 2
#define ARG_ILLEGAL 3

#define MAXARG 2000000000L
#define NOLIMIT (MAXARG+1L)

#define SWBOOLEAN(c,boool) if (sw==c) boool=TRUE;
#define SWINT(c,boool,val,id) if (sw==c) \
    {boool=TRUE;arg_int(&arg,&val,id);}
#define SWRANGE(c,boool,val1,val2,id) if (sw==c) \
    {boool=TRUE;arg_range(&arg,&val1,&val2,id);}

#define FREES free
#define ALLOCS calloc

#define DYNALLSTAT(type,name,name_sz) static type *name; static size_t name_sz=0
#define DYNALLOC1(type,name,name_sz,sz,msg) \
 if ((size_t)(sz) > name_sz) \
 { if (name_sz) FREES(name); name_sz = (sz); \
 if ((name=(type*)ALLOCS(sz,sizeof(type))) == NULL) alloc_error(msg);}
#define DYNALLOC2(type,name,name_sz,sz1,sz2,msg) \
 if ((size_t)(sz1)*(size_t)(sz2) > name_sz) \
 { if (name_sz) FREES(name); name_sz = (size_t)(sz1)*(size_t)(sz2); \
 if ((name=(type*)ALLOCS((sz1),(sz2)*sizeof(type))) == NULL) alloc_error(msg);}
#define DYNFREE(name,name_sz) if (name_sz) {FREES(name); name_sz = 0;}
#define DYNREALLOC(type,name,name_sz,sz,msg) \
 {if ((size_t)(sz) > name_sz) \
 { if ((name = (type*)realloc(name,(sz)*sizeof(type))) == NULL) \
      alloc_error(msg); else name_sz = (sz);}}

#define alloc_error gt_abort

#ifdef __STDC__
#include <stddef.h>
#include <stdlib.h>
#else
#include <sys/types.h>
extern char *calloc();
extern char *malloc();
extern char *realloc();
#endif

#ifdef __alpha
typedef unsigned int setword;
#else
typedef unsigned long setword;
#endif
typedef setword set;
typedef setword graph;
typedef int boolean;

static setword bit[32]=
  {020000000000,010000000000,04000000000,02000000000,
   01000000000,0400000000,0200000000,0100000000,040000000,
   020000000,010000000,04000000,02000000,01000000,0400000,
   0200000,0100000,040000,020000,010000,04000,02000,01000,
   0400,0200,0100,040,020,010,04,02,01};
static int leftbit[] =
  {8,7,6,6,5,5,5,5,4,4,4,4,4,4,4,4,
   3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
   2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
   2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
   1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
   1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
   1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
   1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
static int labelorg = 0;

#define WORDSIZE 32
#define FIRSTBIT(x) ((x) & 037777600000 ? ((x) & 037700000000 ? \
                 leftbit[((x)>>24) & 0377] : 8+leftbit[(x)>>16]) \
                : ((x) & 0177400 ? 16+leftbit[(x)>>8] : 24+leftbit[x]))
#define BITMASK(x)  (017777777777 >> (x)) /* setword whose rightmost
  WORDSIZE-x-1 (numbered) bits are 1 and the rest 0 (0 <= x < WORDSIZE) */
#define TIMESWORDSIZE(w) ((w)<<5)
#define SETWD(pos) ((pos)>>5)
#define SETBT(pos) ((pos)&037)
#define ISELEMENT(setadd,pos)  (((setadd)[SETWD(pos)] & bit[SETBT(pos)]) != 0)
#define ADDELEMENT(setadd,pos)  ((setadd)[SETWD(pos)] |= bit[SETBT(pos)])
#define GRAPHROW(g,v,m) ((set*)(g) + (long)(v) * (long)(m))

#define FALSE 0
#define TRUE  1

/************************************************************************/

#ifndef SEEK_SET
#define SEEK_SET 0
#define SEEK_CUR 1
#define SEEK_END 2
#endif

#ifndef SEEK_CUR
#define SEEK_CUR SEEK_CURRENT
#endif

static long ogf_linelen;

/************************************************************************/

static void
gt_abort(char *msg)     /* Write message and halt. */
{
    if (msg) fprintf(stderr,"%s",msg);
    exit(1);
}

/*****************************************************************************
*                                                                            *
*  itos(i,s) converts the int i to a nul-terminated decimal character        *
*  string s.  The value returned is the number of characters excluding       *
*  the nul.                                                                  *
*                                                                            *
*  GLOBALS ACCESSED: NONE                                                    *
*                                                                            *
*****************************************************************************/

static int
itos(int i, char *s)
{
    int digit,j,k;
    char c;
    int ans;

    if (i < 0)
    {
        k = 0;
        i = -i;
        j = 1;
        s[0] = '-';
    }
    else
    {
        k = -1;
        j = 0;
    }

    do
    {
        digit = i % 10;
        i = i / 10;
        s[++k] = digit + '0';
    }
    while (i);

    s[k+1] = '\0';
    ans = k + 1;

    for (;j < k; ++j, --k)
    {
        c = s[j];
        s[j] = s[k];
        s[k] = c;
    }

    return(ans);
}

/*****************************************************************************
*                                                                            *
*  nextelement(set1,m,pos) = the position of the first element in set set1   *
*  which occupies a position greater than pos.  If no such element exists,   *
*  the value is -1.  pos can have any value less than n, including negative  *
*  values.                                                                   *
*                                                                            *
*  GLOBALS ACCESSED: none                                                    *
*                                                                            *
*****************************************************************************/

static int
nextelement(set *set1, int m, int pos)
{
    setword setwd;
    int w;

    if (pos < 0)
    {
        w = 0;
        setwd = set1[0];
    }
    else
    {
        w = SETWD(pos);
        setwd = set1[w] & BITMASK(SETBT(pos));
    }

    for (;;)
    {
        if (setwd != 0)
            return(TIMESWORDSIZE(w) + FIRSTBIT(setwd));
        if (++w == m) return -1;
        setwd = set1[w];
    }
}

/*********************************************************************
opengraphfile(filename,codetype,assumefixed,position) 
      opens and positions a file for reading graphs.

  filename = the name of the file to open 
            (NULL means stdin, assumed already open)
  codetype   = returns a code for the format.
            This is a combination of SPARSE6, GRAPH6,
            UNKNOWN_TYPE and HAS_HEADER.  If a header is
            present, that overrides the data.  If there is
            no header, the first graph is examined.
  assumefixed = nonzero if files other than stdin should be assumed to
            be seekable and have equal record sizes.
            Ignored if there is a sparse6 header or the first
            graph has sparse6 format.
  position = the number of the record to position to
            (the first is number 1; 0 and -NOLIMIT also mean
             to position at start)

  If the file starts with ">", there must be a header, either
  GRAPH6_HEADER, SPARSE6_HEADER or DIGRAPH6_HEADER.  Otherwise
  opengraphfile() fails.

  The value returned is a file pointer or NULL.  
  If assumedfixed is not zero and position > 1, the global variable
  ogf_linelen is set to the length (including \n) of the length of the 
  first record.

**********************************************************************/

static FILE*
opengraphfile(char *filename, int *codetype, int assumefixed, long position)
{
    FILE *f;
    int c,firstc;
    long i,l,pos,pos1,pos2;
    boolean bad_header;

    if (filename == NULL)
        f = stdin;
    else
    {
        f = fopen(filename,"r");
        if (f == NULL)
        {
            fprintf(stderr,">E opengraphfile: can't open %s\n",filename);
            return NULL;
        }
    }

    firstc = c = getc(f);
    if (c == EOF)
    {
        *codetype = GRAPH6;
        return f;
    }

    if (c != '>')
    {
        *codetype = firstc == ':' ? SPARSE6 : firstc == '&' ? DIGRAPH6 : GRAPH6;
        ungetc(c,f);
    }
    else
    {
        bad_header = FALSE;
        if ((c = getc(f)) == EOF || c != '>')
            bad_header = TRUE;
        if (!bad_header &&
                ((c = getc(f)) == EOF || (c != 'g' && c != 's')))
            bad_header = TRUE;      
        if (!bad_header && c == 'g')
        {
            if ((c = getc(f)) == EOF || c != 'r' ||
                (c = getc(f)) == EOF || c != 'a' ||
                (c = getc(f)) == EOF || c != 'p' ||
                (c = getc(f)) == EOF || c != 'h' ||
                (c = getc(f)) == EOF || c != '6' ||
                (c = getc(f)) == EOF || c != '<' ||
                (c = getc(f)) == EOF || c != '<')
                    bad_header = TRUE;
            else
                *codetype = GRAPH6 | HAS_HEADER;
        }
        else if (!bad_header && c == 'd')
        {
            if ((c = getc(f)) == EOF || c != 'i' ||
                (c = getc(f)) == EOF || c != 'g' ||
                (c = getc(f)) == EOF || c != 'r' ||
                (c = getc(f)) == EOF || c != 'a' ||
                (c = getc(f)) == EOF || c != 'p' ||
                (c = getc(f)) == EOF || c != 'h' ||
                (c = getc(f)) == EOF || c != '6' ||
                (c = getc(f)) == EOF || c != '<' ||
                (c = getc(f)) == EOF || c != '<')
                    bad_header = TRUE;
            else
                *codetype = DIGRAPH6 | HAS_HEADER;
        }
        else if (!bad_header && c == 's')
        {
            if ((c = getc(f)) == EOF || c != 'p' ||
                (c = getc(f)) == EOF || c != 'a' ||
                (c = getc(f)) == EOF || c != 'r' ||
                (c = getc(f)) == EOF || c != 's' ||
                (c = getc(f)) == EOF || c != 'e' ||
                (c = getc(f)) == EOF || c != '6' ||
                (c = getc(f)) == EOF || c != '<' ||
                (c = getc(f)) == EOF || c != '<')
                    bad_header = TRUE;
            else
                *codetype = SPARSE6 | HAS_HEADER;
        }
        if (bad_header)
        {
            fprintf(stderr,">E opengraphfile: illegal header in %s\n",
                    filename == NULL ? "stdin" : filename);
            *codetype = UNKNOWN_TYPE | HAS_HEADER;
            return NULL;
        }
    }

    if (position <= 1) return f;

    if (filename == NULL || !assumefixed || (*codetype&SPARSE6)
                         || firstc == ':')
    {
        l = 1;
        while ((c = getc(f)) != EOF)
        {
            if (c == '\n')
            {
                ++l;
                if (l == position) break;
            }
        }
        if (l == position) return f;

        fprintf(stderr,
           ">E opengraphfile: can't find line %ld in %s\n",position,
            filename == NULL ? "stdin" : filename);
        return NULL;
    }
    else
    {
        pos1 = ftell(f);
        if (pos1 < 0)
        {
            fprintf(stderr,">E opengraphfile: error on first ftell\n");
            return NULL;
        }

        for (i = 1; (c = getc(f)) != EOF && c != '\n'; ++i) {}
        ogf_linelen = i;

        if (c == EOF)
        {
            fprintf(stderr,
                    ">E opengraphfile: required record no present\n");
            return NULL;
        }
        
        pos2 = ftell(f);
        if (pos2 < 0)
        {
            fprintf(stderr,">E opengraphfile: error on second ftell\n");
            return NULL;
        }

        pos = pos1 + (position-1)*(pos2-pos1);
        if (fseek(f,pos,SEEK_SET) < 0)
        {
            fprintf(stderr,">E opengraphfile: seek failed\n");
            return NULL;
        }
    }

    return f;
}

/*********************************************************************/

static char*
showg_getline(FILE *f)     /* read a line with error checking */
       /* includes \n (if present) and \0.
    Immediate EOF causes NULL return. */
{
    DYNALLSTAT(char,s,s_sz);
    int c;
    long i;

    DYNALLOC1(char,s,s_sz,500,"showg_getline");

    i = 0;
    while ((c = getc(f)) != EOF && c != '\n')
    {
        if (i == s_sz-2) DYNREALLOC(char,s,s_sz,s_sz+1000,"showg_getline");
        s[i++] = c;
    }

    if (i == 0 && c == EOF) return NULL;

    if (c == '\n') s[i++] = '\n';
    s[i] = '\0';
    return s;
}

/****************************************************************************/

int
graphsize(char *s)
/* Get size of graph out of graph6, digraph6 or sparse6 string. */
{
    char *p;
    int n;

    if (s[0] == ':' || s[0] == '&') p = s+1;
    else                            p = s;
    n = *p++ - BIAS6;

    if (n > SMALLN)
    {
        n = *p++ - BIAS6;
        if (n > SMALLN)
        {
            n = *p++ - BIAS6;
            n = (n << 6) | (*p++ - BIAS6);
            n = (n << 6) | (*p++ - BIAS6);
            n = (n << 6) | (*p++ - BIAS6);
            n = (n << 6) | (*p++ - BIAS6);
            n = (n << 6) | (*p++ - BIAS6);
        }
        else
        {
            n = (n << 6) | (*p++ - BIAS6);
            n = (n << 6) | (*p++ - BIAS6);
        }
    }
    return n;
}

/****************************************************************************/

static void
stringtograph(char *s, graph *g, int m)
/* Convert string (graph6, digraph6 or sparse6 format) to graph. */
/* Assumes g is big enough to hold it.   */
{
    char *p;
    int n,i,j,k,v,x,nb,need;
    size_t ii;
    set *gi,*gj;
    boolean done;

    n = graphsize(s);
    if (n == 0) return;

    p = s + (s[0] == ':' || s[0] == '&') + SIZELEN(n);

    if (TIMESWORDSIZE(m) < n)
        gt_abort(">E stringtograph: impossible m value\n");

    for (ii = m*(size_t)n; --ii > 0;) g[ii] = 0;
    g[0] = 0;

    if (s[0] != ':' && s[0] != '&')       /* graph6 format */
    {
        k = 1;
        for (j = 1; j < n; ++j)
        {
            gj = GRAPHROW(g,j,m);
    
            for (i = 0; i < j; ++i)
            {
                if (--k == 0)
                {
                    k = 6;
                    x = *(p++) - BIAS6;
                }
        
                if ((x & TOPBIT6))
                {
                    gi = GRAPHROW(g,i,m);
                    ADDELEMENT(gi,j);
                    ADDELEMENT(gj,i);
                }
                x <<= 1;
            }
        }
    }
    else if (s[0] == '&')
    {
        k = 1;
        for (i = 0; i < n; ++i)
        {
            gi = GRAPHROW(g,i,m);
    
            for (j = 0; j < n; ++j)
            {
                if (--k == 0)
                {
                    k = 6;
                    x = *(p++) - BIAS6;
                }
        
                if ((x & TOPBIT6))
                {
                    ADDELEMENT(gi,j);
                }
                x <<= 1;
            }
        } 
    }
    else    /* sparse6 format */
    {
        for (i = n-1, nb = 0; i != 0 ; i >>= 1, ++nb) {}

        k = 0;
        v = 0;
	done = FALSE;
        while (!done)
        {
	    if (k == 0)
	    {
		x = *(p++);
		if (x == '\n' || x == '\0')
		{
		    done = TRUE; continue;
		}
		else
		{
		    x -= BIAS6; k = 6;
		}
	    }
	    if ((x & B(k))) ++v;
	    --k;

	    need = nb;
	    j = 0;
	    while (need > 0 && !done)
	    {
		if (k == 0)
		{
		    x = *(p++);
		    if (x == '\n' || x == '\0')
		    {
		        done = TRUE; continue;
		    }
		    else
		    {
		       	x -= BIAS6; k = 6;
		    }
		}
		if (need >= k)
		{
		    j = (j << k) | (x & M(k));
		    need -= k; k = 0;
		}
		else
		{
		    k -= need;
		    j = (j << need) | ((x >> k) & M(need));
		    need = 0;
		}
	    }
	    if (done) continue;

	    if (j > v)
		v = j;
	    else if (v < n)
	    {
		ADDELEMENT(GRAPHROW(g,v,m),j);
		ADDELEMENT(GRAPHROW(g,j,m),v);
	    }
        }
    }
}

/***********************************************************************/

graph*                 /* read graph into nauty format */
readgg(FILE *f, graph *g, int reqm, int *pm, int *pn, boolean *digraph) 
/* graph6, digraph6 and sparse6 formats are supported 
   f = an open file 
   g = place to put the answer (NULL for dynamic allocation) 
   reqm = the requested value of m (0 => compute from n) 
   *pm = the actual value of m 
   *pn = the value of n 
   *digraph = whether the input is a digraph
*/
{
    char *s,*p;
    int m,n;
    int readg_code;

    if ((s = showg_getline(f)) == NULL) return NULL;

    if (s[0] == ':')
    {
        *digraph = FALSE;
        p = s + 1;
    }
    else if (s[0] == '&')
    {
	readg_code = DIGRAPH6;
        *digraph = TRUE;
	p = s + 1;
    }
    else
    {
        readg_code = GRAPH6;
        *digraph = FALSE;
        p = s;
    }

    while (*p >= BIAS6 && *p <= MAXBYTE) 
        ++p;
    if (*p == '\0')
        gt_abort(">E readgg: missing newline\n");
    else if (*p != '\n')
        gt_abort(">E readgg: illegal character\n");

    n = graphsize(s);
    if (readg_code == GRAPH6 && p - s != G6LEN(n))
        gt_abort(">E readgg: truncated graph6 line\n");
    if (readg_code == DIGRAPH6 && p - s != D6LEN(n))
        gt_abort(">E readgg: truncated digraph6 line\n");

    if (reqm > 0 && TIMESWORDSIZE(reqm) < n)
        gt_abort(">E readgg: reqm too small\n");
    else if (reqm > 0)
        m = reqm;
    else
        m = (n + WORDSIZE - 1) / WORDSIZE;

    if (g == NULL)
    {
        if ((g = (graph*)ALLOCS(n,m*sizeof(graph))) == NULL)
            gt_abort(">E readgg: malloc failed\n");
    }

    *pn = n;
    *pm = m;

    stringtograph(s,g,m);
    return g;
}


/**************************************************************************/

static int
longvalue(char **ps, long *l)
{
    boolean neg,pos;
    long sofar,last;
    char *s;

    s = *ps;
    pos = neg = FALSE;
    if (*s == '-')
    {
        neg = TRUE;
        ++s;
    }
    else if (*s == '+')
    {
        pos = TRUE;
        ++s;
    }

    if (*s < '0' || *s > '9') 
    {
        *ps = s;
        return (pos || neg) ? ARG_ILLEGAL : ARG_MISSING;
    }

    sofar = 0;

    for (; *s >= '0' && *s <= '9'; ++s)
    {
        last = sofar;
        sofar = sofar * 10 + (*s - '0');
        if (sofar < last || sofar > MAXARG)
        {
            *ps = s;
            return ARG_TOOBIG;
        }
    }
    *ps = s;
    *l = neg ? -sofar : sofar;
    return ARG_OK;
}
    
/*************************************************************************/

static void
arg_int(char **ps, int *val, char *id)
{
    int code;
    long longval;

    code = longvalue(ps,&longval);
    *val = longval;
    if (code == ARG_MISSING || code == ARG_ILLEGAL)
    {
        fprintf(stderr,">E %s: missing argument value\n",id);
        gt_abort(NULL);
    }
    else if (code == ARG_TOOBIG || *val != longval)
    {
        fprintf(stderr,">E %s: argument value too large\n",id);
        gt_abort(NULL);
    }
}

/************************************************************************/

static void
arg_range(char **ps, long *val1, long *val2, char *id)
{
    int code;
    char *s;

    s = *ps;
    code = longvalue(&s,val1);
    if (code != ARG_MISSING)
    {
        if (code == ARG_ILLEGAL)
        {
            fprintf(stderr,">E %s: bad range\n",id);
            gt_abort(NULL);
        }
        else if (code == ARG_TOOBIG)
        {
            fprintf(stderr,">E %s: value too big\n",id);
            gt_abort(NULL);
        }
    }
    else if (*s != ':' && *s != '-')
    {
        fprintf(stderr,">E %s: missing value\n",id);
        gt_abort(NULL);
    }
    else
        *val1 = -NOLIMIT;

    if (*s == ':' || *s == '-')
    {
        ++s;
        code = longvalue(&s,val2);
        if (code == ARG_MISSING)
            *val2 = NOLIMIT;
        else if (code == ARG_TOOBIG)
        {
            fprintf(stderr,">E %s: value too big\n",id);
            gt_abort(NULL);
        }
        else if (code == ARG_ILLEGAL)
        {
            fprintf(stderr,">E %s: illegal range\n",id);
            gt_abort(NULL);
        }
    }
    else
        *val2 = *val1;

    *ps = s;
}

/************************************************************************/

#define LABELORG 0   /* number of first vertex (any integer >= 0) */
#define LINELEN 78   /* max characters per line (0 = no limit) */

static FILE *infile,*outfile;
static long nin;

/*****************************************************************************
*                                                                            *
*  putsetx(f,set1,curlenp,linelength,m,compress,start)   writes the set      *
*  set1 to file f using at most linelength characters per line (excluding    *
*  '\n').   Set elements less than or equal to start are ignored.            *
*  *curlenp is the number of characters on the line so far; it is updated.   *
*  A range j1,j1+1,...,j2 for j2-j1>=2 is written as "j1:j2" if compress     *
*  is nonzero (eg. TRUE); otherwise each element is written separately.      *
*  No final '\n' is written.  labelorg is used.                              *
*                                                                            *
*  FUNCTIONS CALLED: nextelement(),itos()                                    *
*                                                                            *
*****************************************************************************/

static void
putsetx(FILE *f, set *set1, int *curlenp, int linelength, int m,
    boolean compress, int start)
{
    int slen,j1,j2;
    char s[40];
    boolean first;

    first = TRUE;
    j1 = start;
    while ((j1 = nextelement(set1,m,j1)) >= 0)
    {
        j2 = j1;
        if (compress)
        {
            while (nextelement(set1,m,j2) == j2 + 1)
                ++j2;
            if (j2 == j1+1)
                j2 = j1;
        }
        slen = itos(j1 + labelorg,s);
        if (j2 >= j1 + 2)
        {
            s[slen] = ':';
            slen += 1 + itos(j2 + labelorg,&s[slen+1]);
        }

        if (*curlenp + slen + 1 >= linelength && linelength > 0)
        {
            fprintf(f,"\n ");
            *curlenp = 1;
        }
        if (first)
        {
            fprintf(f,"%s",s);
            *curlenp += slen;
            first = FALSE;
        }
        else
        {    
            fprintf(f," %s",s);
            *curlenp += slen + 1;
        }
        j1 = j2;
    }
}

/*****************************************************************************
*                                                                            *
*  STOLEN FROM naututil.c                                                    *
*  putgraphx(f,g,linelength,m,n) writes a list of the edges of g to f        *
*  using at most linelength characters per line (excluding '\n').            *
*  If triang, only write the upper triangle.                                 *
*  labelorg is used.                                                         *
*                                                                            *
*****************************************************************************/

static void
putgraphx(FILE *f, graph *g, int linelength, boolean triang, int m, int n)
{
    int i,curlen;
    set *pg;

    for (i = 0, pg = g; i < n; ++i, pg += m)
    {
        fprintf(f,"%3d : ",i + labelorg);
        curlen = 7;
        putsetx(f,pg,&curlen,linelength,m,FALSE,triang ? i-1 : -1);
        fprintf(f,";\n");
    }
}

/***************************************************************************/

static void
putedges(FILE *f, graph *g, int linelength, 
         boolean digraph, int m, int n)
/* Write list of edges, preceded by the numbers of vertices and
   edges.  Use labelorg */
{
    int i,j,curlen,ne;
    char s[20];
    set *pg;

    ne = 0;
    for (i = 0, pg = g; i < n; ++i, pg += m)
    {
        for (j = (digraph?-1:i-1); (j = nextelement(pg,m,j)) >= 0;)
            ++ne;
    }

    fprintf(f,"%d %d\n",n,ne);

    curlen = 0;
    for (i = 0, pg = g; i < n; ++i, pg += m)
    {
        for (j = (digraph ? -1 : i-1); (j = nextelement(pg,m,j)) >= 0;)
        { 
            if (curlen > 0 && curlen > linelength - 10 && linelength > 0)
            {
                fprintf(f,"\n");
                curlen = 0;
            }
            if (curlen > 0)
            {
                fprintf(f,"  ");
                curlen += 2;
            }
            curlen += itos(i+labelorg,s);
            fprintf(f,"%s",s);
            fprintf(f," ");
            curlen += 1 + itos(j+labelorg,s);
            fprintf(f,"%s",s);
        }
    }
    fprintf(f,"\n");
}

/***************************************************************************/

static void
putcgraph(FILE *f, graph *g, int linelength, boolean digraph, int m, int n)
/* write compressed form, using labelorg */
{
    int i,curlen,j0;
    int semicolons;
    char s[20];
    set *pg;

    curlen = itos(n,s)+2;
    fprintf(f,";n%s%s",s,(digraph?"dg":"g"));

    semicolons = 0;
    for (i = 0, pg = g; i < n; ++i, pg += m)
    {
	j0 = digraph ? -1: i-1;
        if (nextelement(pg,m,j0) >= 0)
        {
            while (semicolons > 0)
            {
                if (curlen >= linelength-1 && linelength > 0)
                {
                    fprintf(f,"\n ");
                    curlen = 1;
                }
                fprintf(f,";");
                ++curlen;
                --semicolons;
            }
            putsetx(f,pg,&curlen,linelength,m,FALSE,j0);
            semicolons = 1;
        }
        else
            ++semicolons;
    }
    fprintf(f,".\n");
}

/**************************************************************************/

static void
putam(FILE *f, graph *g, int linelength, boolean space, boolean triang,
      int m, int n)   /* write adjacency matrix */
{
    set *gi;
    int i,j;
    boolean first;

    for (i = 0, gi = (set*)g; i < n - (triang!=0); ++i, gi += m)
    {
        first = TRUE;
        for (j = triang ? i+1 : 0; j < n; ++j)
        {
            if (!first && space) putc(' ',f);
            else                 first = FALSE;
            if (ISELEMENT(gi,j)) putc('1',f);
            else                 putc('0',f);
        }
        putc('\n',f);
    }
}

/**************************************************************************/
/**************************************************************************/

int
main(int argc, char *argv[])
{
    graph *g;
    int m,n,codetype;
    int argnum,j;
    char *arg,sw;
    boolean badargs,digraph;
    long maxin,pval1,pval2;
    boolean fswitch,pswitch,cswitch,dswitch;
    boolean aswitch,lswitch,oswitch,Fswitch;
    boolean Aswitch,eswitch,tswitch,qswitch;
    int linelength;
    char *infilename,*outfilename;

    if (argc > 1 && (strcmp(argv[1],"-help") == 0
                   || (strcmp(argv[1],"--help") == 0)))
    {
        printf("Usage: %s\n\n%s",USAGE,HELPTEXT);
        exit(0);
    }

    if (sizeof(setword) < 4)
    {
        fprintf(stderr,">E showg: setword too small\n");
        fprintf(stderr,"   Please report this to bdm@cs.anu.edu.au\n");
        exit(1);
    }

    fswitch = pswitch = cswitch = dswitch = FALSE;
    aswitch = lswitch = oswitch = Fswitch = FALSE;
    Aswitch = eswitch = tswitch = qswitch = FALSE;
    infilename = outfilename = NULL;
    linelength = LINELEN;
    labelorg = 0;

    argnum = 0;
    badargs = FALSE;
    for (j = 1; !badargs && j < argc; ++j)
    {
        arg = argv[j];
        if (arg[0] == '-' && arg[1] != '\0')
        {
            ++arg;
            while (*arg != '\0')
            {
                sw = *arg++;
                     SWBOOLEAN('a',aswitch)
                else SWBOOLEAN('A',Aswitch)
                else SWBOOLEAN('c',cswitch)
                else SWBOOLEAN('d',dswitch)
                else SWBOOLEAN('e',eswitch)
                else SWBOOLEAN('f',fswitch)
                else SWBOOLEAN('F',Fswitch)
                else SWBOOLEAN('t',tswitch)
                else SWBOOLEAN('q',qswitch)
                else SWRANGE('p',pswitch,pval1,pval2,"showg -p")
                else SWINT('l',lswitch,linelength,"showg -l")
                else SWINT('o',oswitch,labelorg,"listo -o")
                else badargs = TRUE;
            }
        }
        else
        {
            ++argnum;
            if      (argnum == 1) infilename = arg;
            else if (argnum == 2) outfilename = arg;
            else                  badargs = TRUE;
        }
    }

    if (labelorg < 0) gt_abort(">E showg: negative origin forbidden.\n");

    if ((aswitch!=0) + (Aswitch!=0) + (eswitch!=0) 
                     + (dswitch!=0) + (cswitch!=0) > 1)
        gt_abort(">E showg: -aAecd are incompatible\n");

    if (badargs)
    {
        fprintf(stderr,">E Usage: %s\n",USAGE);
        fprintf(stderr,"Use showg -help to see a list of the options.\n");
        exit(1);
    }

    if (!pswitch || pval1 < 1) pval1 = 1;

    if (infilename && infilename[0] == '-') infilename = NULL;
    infile = opengraphfile(infilename,&codetype,fswitch,
                           pswitch ? pval1 : 1);
    if (!infile) exit(1);
    if (!infilename) infilename = "stdin";

    if (!outfilename || outfilename[0] == '-')
    {
        outfilename = "stdout";
        outfile = stdout;
    }
    else if ((outfile = fopen(outfilename,"w")) == NULL)
    {
        fprintf(stderr,"Can't open output file %s\n",outfilename);
        gt_abort(NULL);
    }

    nin = 0;
    if (!pswitch || pval2 == NOLIMIT)
        maxin = NOLIMIT;
    else if (pval1 < 1) maxin = pval2;
    else                maxin = pval2 - pval1 + 1;
    while (nin < maxin || maxin == NOLIMIT)
    {
        if ((g = readgg(infile,NULL,0,&m,&n,&digraph)) == NULL) break;
        ++nin;

        if (Fswitch && nin > 1) fprintf(outfile,"\f");

        if (cswitch)
            putcgraph(outfile,g,linelength,digraph,m,n);
        else if (dswitch)
        {
            if (qswitch)
                fprintf(outfile,"%d\n",n);
            else
            {
                fprintf(outfile,"\n!Graph %ld.\n",pval1+nin-1);
                fprintf(outfile,"n=%d $=%d g\n",n,labelorg);
            }
            putgraphx(outfile,g,linelength,tswitch,m,n);
            if (!qswitch) fprintf(outfile,"$$\n");
        }
        else
        {
            if (qswitch)
            {
                if (!eswitch) fprintf(outfile,"%d\n",n);
            }
            else fprintf(outfile,"\nGraph %ld, order %d.\n",
                                 pval1+nin-1,n);
            if (aswitch|Aswitch)
                putam(outfile,g,linelength,Aswitch,tswitch,m,n);
            else if (eswitch)
                putedges(outfile,g,linelength,digraph,m,n);
            else
                putgraphx(outfile,g,linelength,tswitch,m,n);
        }
        FREES(g);
    }

    exit(0);
}
