/*
 * xvbmp.c - i/o routines for .BMP files (MS Windows 3.x)
 *
 * LoadBMP(fname, numcols)
 * WriteBMP(fp, pic, ptype, w, h, r, g, b, numcols, style);
 */

#include "copyright.h"

#include "xv.h"

/* comments on error handling:
   a truncated file is not considered a Major Error.  The file is loaded, the
   rest of the pic is filled with 0's.

   a file with garbage characters in it is an unloadable file.  All allocated
   stuff is tossed, and LoadPBM returns non-zero

   not being able to malloc is a Fatal Error.  The program is aborted. */


#define BI_RGB  0
#define BI_RLE8 1
#define BI_RLE4 2

#define WIN_OS2_OLD 12
#define WIN_NEW     40
#define OS2_NEW     64

static long filesize;

static int   loadBMP1   PARM((FILE *, byte *, u_int, u_int));
static int   loadBMP4   PARM((FILE *, byte *, u_int, u_int, u_int));
static int   loadBMP8   PARM((FILE *, byte *, u_int, u_int, u_int));
static int   loadBMP24  PARM((FILE *, byte *, u_int, u_int, u_int));
static u_int getshort   PARM((FILE *));
static u_int getint     PARM((FILE *));
static void  putshort   PARM((FILE *, int));
static void  putint     PARM((FILE *, int));
static void  writeBMP1  PARM((FILE *, byte *, int, int));
static void  writeBMP4  PARM((FILE *, byte *, int, int));
static void  writeBMP8  PARM((FILE *, byte *, int, int));
static void  writeBMP24 PARM((FILE *, byte *, int, int));
static int   bmpError   PARM((char *, char *));


#define FERROR(fp) (ferror(fp) || feof(fp))

/*******************************************/
int LoadBMP(fname, pinfo)
     char    *fname;
     PICINFO *pinfo;
/*******************************************/
{
  FILE         *fp;
  int          i, c, c1, rv;
  unsigned int bfSize, bfOffBits, biSize, biWidth, biHeight, biPlanes;
  unsigned int biBitCount, biCompression, biSizeImage, biXPelsPerMeter;
  unsigned int biYPelsPerMeter, biClrUsed, biClrImportant;
  int bPad;
  char         *cmpstr;
  byte         *pic24, *pic8;
  char          buf[512], *bname;

  /* returns '1' on success */

  pic8 = pic24 = (byte *) NULL;
  bname = BaseName(fname);

  fp = xv_fopen(fname,"r");
  if (!fp) return (bmpError(bname, "couldn't open file"));
  
  fseek(fp, 0L, 2);      /* figure out the file size */
  filesize = ftell(fp);
  fseek(fp, 0L, 0);


  /* read the file type (first two bytes) */
  c = getc(fp);  c1 = getc(fp);
  if (c!='B' || c1!='M') { bmpError(bname,"file type != 'BM'"); goto ERROR; }

  bfSize = getint(fp);
  getshort(fp);         /* reserved and ignored */
  getshort(fp);
  bfOffBits = getint(fp);

  biSize          = getint(fp);

  if (biSize == WIN_NEW || biSize == OS2_NEW) {
    biWidth         = getint(fp);
    biHeight        = getint(fp);
    biPlanes        = getshort(fp);
    biBitCount      = getshort(fp);
    biCompression   = getint(fp);
    biSizeImage     = getint(fp);
    biXPelsPerMeter = getint(fp);
    biYPelsPerMeter = getint(fp);
    biClrUsed       = getint(fp);
    biClrImportant  = getint(fp);
  }

  else {    /* old bitmap format */
    biWidth         = getshort(fp);          /* Types have changed ! */
    biHeight        = getshort(fp);
    biPlanes        = getshort(fp);
    biBitCount      = getshort(fp);
    
    /* Not in old versions so have to compute them*/
    biSizeImage = (((biPlanes * biBitCount*biWidth)+31)/32)*4*biHeight;
    
    biCompression   = BI_RGB; 
    biXPelsPerMeter = biYPelsPerMeter = 0;
    biClrUsed       = biClrImportant  = 0;
  }

  if (DEBUG>1) {
    fprintf(stderr,"\nLoadBMP:\tbfSize=%d, bfOffBits=%d\n",bfSize,bfOffBits);
    fprintf(stderr,"\t\tbiSize=%d, biWidth=%d, biHeight=%d, biPlanes=%d\n",
	    biSize, biWidth, biHeight, biPlanes);
    fprintf(stderr,"\t\tbiBitCount=%d, biCompression=%d, biSizeImage=%d\n",
	    biBitCount, biCompression, biSizeImage);
    fprintf(stderr,"\t\tbiX,YPelsPerMeter=%d,%d  biClrUsed=%d, biClrImp=%d\n",
	    biXPelsPerMeter, biYPelsPerMeter, biClrUsed, biClrImportant);
  }

  if (FERROR(fp)) { bmpError(bname,"EOF reached in file header"); goto ERROR; }


  /* error checking */
  if ((biBitCount!=1 && biBitCount!=4 && biBitCount!=8 && 
       biBitCount!=24 && biBitCount!=32) || 
       biPlanes!=1 || biCompression>BI_RLE4 ||
       biWidth<= 0 || biHeight <= 0 ||
       (biClrUsed && biClrUsed > (1 << biBitCount))) {

    sprintf(buf,"Bogus BMP File!  (bitCount=%d, Planes=%d, Compression=%d)",
	    biBitCount, biPlanes, biCompression);

    bmpError(bname, buf);
    goto ERROR;
  }

  if (((biBitCount==1 || biBitCount==24 || biBitCount==32)
       && biCompression != BI_RGB) ||
      (biBitCount==4 && biCompression==BI_RLE8) ||
      (biBitCount==8 && biCompression==BI_RLE4)) {

    sprintf(buf,"Bogus BMP File!  (bitCount=%d, Compression=%d)",
	    biBitCount, biCompression);

    bmpError(bname, buf);
    goto ERROR;
  }


  bPad = 0;
  if (biSize != WIN_OS2_OLD) {
    /* skip ahead to colormap, using biSize */
    c = biSize - 40;    /* 40 bytes read from biSize to biClrImportant */
    for (i=0; i<c; i++) getc(fp);
    
    bPad = bfOffBits - (biSize + 14);
  }

  if (biClrUsed > (1 << biBitCount))
    biClrUsed = (1 << biBitCount);

  /* load up colormap, if any */
  if (biBitCount!=24 && biBitCount!=32) {
    int i, cmaplen;

    cmaplen = (biClrUsed) ? biClrUsed : 1 << biBitCount;
    for (i=0; i<cmaplen; i++) {
      pinfo->b[i] = getc(fp);
      pinfo->g[i] = getc(fp);
      pinfo->r[i] = getc(fp);
      if (biSize != WIN_OS2_OLD) {
	getc(fp);
	bPad -= 4;
      }
    }

    if (FERROR(fp)) 
      { bmpError(bname,"EOF reached in BMP colormap"); goto ERROR; }

    if (DEBUG>1) {
      fprintf(stderr,"LoadBMP:  BMP colormap:  (RGB order)\n");
      for (i=0; i<cmaplen; i++) {
	fprintf(stderr,"%02x%02x%02x  ", pinfo->r[i],pinfo->g[i],pinfo->b[i]);
      }
      fprintf(stderr,"\n\n");
    }
  }

  if (biSize != WIN_OS2_OLD) {
    /* Waste any unused bytes between the colour map (if present)
       and the start of the actual bitmap data. */
    
    while (bPad > 0) {
      (void) getc(fp);
      bPad--;
    }
  }

  /* create pic8 or pic24 */

  if (biBitCount==24 || biBitCount==32) {
    pic24 = (byte *) calloc((size_t) biWidth * biHeight * 3, (size_t) 1);
    if (!pic24) return (bmpError(bname, "couldn't malloc 'pic24'"));
  }
  else {
    pic8 = (byte *) calloc((size_t) biWidth * biHeight, (size_t) 1);
    if (!pic8) return(bmpError(bname, "couldn't malloc 'pic8'"));
  }

  WaitCursor();

  /* load up the image */
  if      (biBitCount == 1) rv = loadBMP1(fp,pic8,biWidth,biHeight);
  else if (biBitCount == 4) rv = loadBMP4(fp,pic8,biWidth,biHeight,
					  biCompression);
  else if (biBitCount == 8) rv = loadBMP8(fp,pic8,biWidth,biHeight, 
					  biCompression);
  else                      rv = loadBMP24(fp,pic24,biWidth,biHeight,
					   biBitCount);


  if (rv) bmpError(bname, "File appears truncated.  Winging it.\n");

  fclose(fp);


  if (biBitCount == 24 || biBitCount == 32) {
    pinfo->pic  = pic24;
    pinfo->type = PIC24;
  }
  else {
    pinfo->pic  = pic8;
    pinfo->type = PIC8;
  }

  cmpstr = "";
  if      (biCompression == BI_RLE4) cmpstr = ", RLE4 compressed";
  else if (biCompression == BI_RLE8) cmpstr = ", RLE8 compressed";

  pinfo->w = biWidth;  pinfo->h = biHeight;
  pinfo->normw = pinfo->w;   pinfo->normh = pinfo->h;
  pinfo->frmType = F_BMP;
  pinfo->colType = F_FULLCOLOR;

  sprintf(pinfo->fullInfo, "%sBMP, %d bit%s per pixel%s.  (%ld bytes)",
	  ((biSize==WIN_OS2_OLD) ? "Old OS/2 " :
	   (biSize==WIN_NEW)     ? "Windows "  : ""),
	  biBitCount,  (biBitCount == 1) ? "" : "s",
	  cmpstr, filesize);

  sprintf(pinfo->shrtInfo, "%dx%d BMP.", biWidth, biHeight);
  pinfo->comment = (char *) NULL;

  return 1;


 ERROR:
  fclose(fp);
  return 0;
}  


/*******************************************/
static int loadBMP1(fp, pic8, w, h)
     FILE *fp;
     byte *pic8;
     u_int  w,h;
{
  int   i,j,c,bitnum,padw;
  byte *pp = pic8 + ((h - 1) * w);
  size_t l = w*h;

  c = 0;
  padw = ((w + 31)/32) * 32;  /* 'w', padded to be a multiple of 32 */

  for (i=h-1; i>=0 && (pp - pic8 <= l); i--) {
    pp = pic8 + (i * w);
    if ((i&0x3f)==0) WaitCursor();
    for (j=bitnum=0; j<padw; j++,bitnum++) {
      if ((bitnum&7) == 0) { /* read the next byte */
	c = getc(fp);
	bitnum = 0;
      }
      
      if (j<w) {
	*pp++ = (c & 0x80) ? 1 : 0;
	c <<= 1;
      }
    }
    if (FERROR(fp)) break;
  }

  return (FERROR(fp));
}  



/*******************************************/
static int loadBMP4(fp, pic8, w, h, comp)
     FILE *fp;
     byte *pic8;
     u_int  w,h,comp;
{
  int   i,j,c,c1,x,y,nybnum,padw,rv;
  byte *pp = pic8 + ((h - 1) * w);
  size_t l = w*h;
  
  rv = 0;
  c = c1 = 0;
  
  if (comp == BI_RGB) {   /* read uncompressed data */
    padw = ((w + 7)/8) * 8; /* 'w' padded to a multiple of 8pix (32 bits) */
    
    for (i=h-1; i>=0 && (pp - pic8 <= l); i--) {
      pp = pic8 + (i * w);
      if ((i&0x3f)==0) WaitCursor();
      
      for (j=nybnum=0; j<padw; j++,nybnum++) {
	if ((nybnum & 1) == 0) { /* read next byte */
	  c = getc(fp);
	  nybnum = 0;
	}
	
	if (j<w) {
	  *pp++ = (c & 0xf0) >> 4;
	  c <<= 4;
	}
      }
      if (FERROR(fp)) break;
    }
  }
  
  else if (comp == BI_RLE4) {  /* read RLE4 compressed data */
    x = y = 0;  
    pp = pic8 + x + (h-y-1)*w;
    
    while (y<h) {
      c = getc(fp);  if (c == EOF) { rv = 1;  break; }
      
      if (c) {                                   /* encoded mode */
	c1 = getc(fp);
	for (i=0; i<c && (pp - pic8 <= l); i++,x++,pp++) 
	  *pp = (i&1) ? (c1 & 0x0f) : ((c1>>4)&0x0f);
      }
      
      else {    /* c==0x00  :  escape codes */
	c = getc(fp);  if (c == EOF) { rv = 1;  break; }
	
	if      (c == 0x00) {                    /* end of line */
	  x=0;  y++;  pp = pic8 + x + (h-y-1)*w;
	} 
	
	else if (c == 0x01) break;               /* end of pic8 */
	
	else if (c == 0x02) {                    /* delta */
	  c = getc(fp);  x += c;
	  c = getc(fp);  y += c;
	  pp = pic8 + x + (h-y-1)*w;
	}
	
	else {                                   /* absolute mode */
	  for (i=0; i<c && (pp - pic8 <= l); i++, x++, pp++) {
	    if ((i&1) == 0) c1 = getc(fp);
	    *pp = (i&1) ? (c1 & 0x0f) : ((c1>>4)&0x0f);
	  }
	  
	  if (((c&3)==1) || ((c&3)==2)) getc(fp);  /* read pad byte */
	}
      }  /* escape processing */
      if (FERROR(fp)) break;
    }  /* while */
  }
  
  else {
    fprintf(stderr,"unknown BMP compression type 0x%0x\n", comp);
  }
  
  if (FERROR(fp)) rv = 1;
  return rv;
}  



/*******************************************/
static int loadBMP8(fp, pic8, w, h, comp)
     FILE *fp;
     byte *pic8;
     u_int  w,h,comp;
{
  int   i,j,c,c1,padw,x,y,rv;
  byte *pp = pic8 + ((h - 1) * w);
  size_t l = w*h;
  
  rv = 0;

  if (comp == BI_RGB) {   /* read uncompressed data */
    padw = ((w + 3)/4) * 4; /* 'w' padded to a multiple of 4pix (32 bits) */

    for (i=h-1; i>=0 && (pp - pic8 <= l); i--) {
      pp = pic8 + (i * w);
      if ((i&0x3f)==0) WaitCursor();

      for (j=0; j<padw; j++) {
	c = getc(fp);  if (c==EOF) rv = 1;
	if (j<w) *pp++ = c;
      }
      if (FERROR(fp)) break;
    }
  }

  else if (comp == BI_RLE8) {  /* read RLE8 compressed data */
    x = y = 0;  
    pp = pic8 + x + (h-y-1)*w;

    while (y<h) {
      c = getc(fp);  if (c == EOF) { rv = 1;  break; }

      if (c) {                                   /* encoded mode */
	c1 = getc(fp);
	for (i=0; i<c && (pp - pic8 <= l); i++,x++,pp++) *pp = c1;
      }

      else {    /* c==0x00  :  escape codes */
	c = getc(fp);  if (c == EOF) { rv = 1;  break; }

	if      (c == 0x00) {                    /* end of line */
	  x=0;  y++;  pp = pic8 + x + (h-y-1)*w;
	} 

	else if (c == 0x01) break;               /* end of pic8 */

	else if (c == 0x02) {                    /* delta */
	  c = getc(fp);  x += c;
	  c = getc(fp);  y += c;
	  pp = pic8 + x + (h-y-1)*w;
	}

	else {                                   /* absolute mode */
	  for (i=0; i<c && (pp - pic8 <= l); i++, x++, pp++) {
	    c1 = getc(fp);
	    *pp = c1;
	  }
	  
	  if (c & 1) getc(fp);  /* odd length run: read an extra pad byte */
	}
      }  /* escape processing */
      if (FERROR(fp)) break;
    }  /* while */
  }
  
  else {
    fprintf(stderr,"unknown BMP compression type 0x%0x\n", comp);
  }

  if (FERROR(fp)) rv = 1;
  return rv;
}  



/*******************************************/
static int loadBMP24(fp, pic24, w, h, bits)
     FILE *fp;
     byte *pic24;
     u_int  w,h, bits;
{
  int   i,j,padb,rv;
  byte *pp = pic24 + ((h - 1) * w * 3);
  size_t l = w*h*3;

  rv = 0;

  padb = (4 - ((w*3) % 4)) & 0x03;  /* # of pad bytes to read at EOscanline */
  if (bits==32) padb = 0;

  for (i=h-1; i>=0 && (pp - pic24 <= l); i--) {
    pp = pic24 + (i * w * 3);
    if ((i&0x3f)==0) WaitCursor();
    
    for (j=0; j<w; j++) {
      pp[2] = getc(fp);   /* blue */
      pp[1] = getc(fp);   /* green */
      pp[0] = getc(fp);   /* red */
      if (bits==32) getc(fp);
      pp += 3;
    }

    for (j=0; j<padb; j++) getc(fp);

    rv = (FERROR(fp));
    if (rv) break;
  }

  return rv;
}  



/*******************************************/
static unsigned int getshort(fp)
     FILE *fp;
{
  int c, c1;
  c = getc(fp);  c1 = getc(fp);
  return ((unsigned int) c) + (((unsigned int) c1) << 8);
}


/*******************************************/
static unsigned int getint(fp)
     FILE *fp;
{
  int c, c1, c2, c3;
  c = getc(fp);  c1 = getc(fp);  c2 = getc(fp);  c3 = getc(fp);
  return ((unsigned int) c) +
         (((unsigned int) c1) << 8) + 
	 (((unsigned int) c2) << 16) +
	 (((unsigned int) c3) << 24);
}


/*******************************************/
static void putshort(fp, i)
     FILE *fp;
     int i;
{
  int c, c1;

  c = ((unsigned int ) i) & 0xff;  c1 = (((unsigned int) i)>>8) & 0xff;
  putc(c, fp);   putc(c1,fp);
}


/*******************************************/
static void putint(fp, i)
     FILE *fp;
     int i;
{
  int c, c1, c2, c3;
  c  = ((unsigned int ) i)      & 0xff;  
  c1 = (((unsigned int) i)>>8)  & 0xff;
  c2 = (((unsigned int) i)>>16) & 0xff;
  c3 = (((unsigned int) i)>>24) & 0xff;

  putc(c, fp);   putc(c1,fp);  putc(c2,fp);  putc(c3,fp);
}




static byte pc2nc[256],r1[256],g1[256],b1[256];


/*******************************************/
int WriteBMP(fp,pic824,ptype,w,h,rmap,gmap,bmap,numcols,colorstyle)
     FILE *fp;
     byte *pic824;
     int   ptype,w,h;
     byte *rmap, *gmap, *bmap;
     int   numcols, colorstyle;
{
  /*
   * if PIC8, and colorstyle == F_FULLCOLOR, F_GREYSCALE, or F_REDUCED,
   * the program writes an uncompressed 4- or 8-bit image (depending on
   * the value of numcols)
   *
   * if PIC24, and colorstyle == F_FULLCOLOR, program writes an uncompressed
   *    24-bit image
   * if PIC24 and colorstyle = F_GREYSCALE, program writes an uncompressed
   *    8-bit image
   * note that PIC24 and F_BWDITHER/F_REDUCED won't happen
   *
   * if colorstyle == F_BWDITHER, it writes a 1-bit image 
   *
   */

  int i,j, nc, nbits, bperlin, cmaplen;
  byte *graypic, *sp, *dp, graymap[256];

  nc = nbits = cmaplen = 0;
  graypic = NULL;

  if (ptype == PIC24 && colorstyle == F_GREYSCALE) {
    /* generate a faked 8-bit per pixel image with a grayscale cmap,
       so that it can just fall through existing 8-bit code */

    graypic = (byte *) malloc((size_t) w*h);
    if (!graypic) FatalError("unable to malloc in WriteBMP()");

    for (i=0,sp=pic824,dp=graypic; i<w*h; i++,sp+=3, dp++) {
      *dp = MONO(sp[0],sp[1],sp[2]);
    }

    for (i=0; i<256; i++) graymap[i] = i;
    rmap = gmap = bmap = graymap;
    numcols = 256;
    ptype = PIC8;

    pic824 = graypic;
  }


  if (ptype == PIC24) {  /* is F_FULLCOLOR */
    nbits = 24;
    cmaplen = 0;
    nc = 0;
  }

  else if (ptype == PIC8) {
    /* we may have duplicate colors in the colormap, and we'd prefer not to.
     * build r1,g1,b1 (a contiguous, minimum set colormap), and pc2nc[], a
     * array that maps 'pic8' values (0-numcols) into corresponding values
     * in the r1,g1,b1 colormaps (0-nc)
     */

    for (i=0; i<256; i++) { pc2nc[i] = r1[i] = g1[i] = b1[i] = 0; }

    nc = 0;
    for (i=0; i<numcols; i++) {
      /* see if color #i is a duplicate */
      for (j=0; j<i; j++) {
	if (rmap[i] == rmap[j] && gmap[i] == gmap[j] && 
	    bmap[i] == bmap[j]) break;
      }

      if (j==i) {  /* wasn't found */
	pc2nc[i] = nc;
	r1[nc] = rmap[i];
	g1[nc] = gmap[i];
	b1[nc] = bmap[i];
	nc++;
      }
      else pc2nc[i] = pc2nc[j];
    }

    /* determine how many bits per pixel we'll be writing */
    if (colorstyle == F_BWDITHER || nc <= 2) nbits = 1;
    else if (nc<=16) nbits = 4;
    else nbits = 8;

    cmaplen = 1<<nbits;                      /* # of entries in cmap */
  }


  bperlin = ((w * nbits + 31) / 32) * 4;   /* # bytes written per line */

  putc('B', fp);  putc('M', fp);           /* BMP file magic number */

  /* compute filesize and write it */
  i = 14 +                /* size of bitmap file header */
      40 +                /* size of bitmap info header */
      (nc * 4) +          /* size of colormap */
      bperlin * h;        /* size of image data */

  putint(fp, i);
  putshort(fp, 0);        /* reserved1 */
  putshort(fp, 0);        /* reserved2 */
  putint(fp, 14 + 40 + (nc * 4));  /* offset from BOfile to BObitmap */

  putint(fp, 40);         /* biSize: size of bitmap info header */
  putint(fp, w);          /* biWidth */
  putint(fp, h);          /* biHeight */
  putshort(fp, 1);        /* biPlanes:  must be '1' */
  putshort(fp, nbits);    /* biBitCount: 1,4,8, or 24 */
  putint(fp, BI_RGB);     /* biCompression:  BI_RGB, BI_RLE8 or BI_RLE4 */
  putint(fp, bperlin*h);  /* biSizeImage:  size of raw image data */
  putint(fp, 75 * 39);    /* biXPelsPerMeter: (75dpi * 39" per meter) */
  putint(fp, 75 * 39);    /* biYPelsPerMeter: (75dpi * 39" per meter) */
  putint(fp, nc);         /* biClrUsed: # of colors used in cmap */
  putint(fp, nc);         /* biClrImportant: same as above */


  /* write out the colormap */
  for (i=0; i<nc; i++) {
    if (colorstyle == F_GREYSCALE) {
      j = MONO(r1[i],g1[i],b1[i]);
      putc(j,fp);  putc(j,fp);  putc(j,fp);  putc(0,fp);
    }
    else {
      putc(b1[i],fp);
      putc(g1[i],fp);
      putc(r1[i],fp);
      putc(0,fp);
    }
  }

  /* write out the image */
  if      (nbits ==  1) writeBMP1 (fp, pic824, w, h);
  else if (nbits ==  4) writeBMP4 (fp, pic824, w, h);
  else if (nbits ==  8) writeBMP8 (fp, pic824, w, h);
  else if (nbits == 24) writeBMP24(fp, pic824, w, h);

  if (graypic) free(graypic);

#ifndef VMS
  if (FERROR(fp)) return -1;
#else
  if (!FERROR(fp)) return -1;
#endif
  
  return 0;
}


	  
	  
/*******************************************/
static void writeBMP1(fp, pic8, w, h)
     FILE *fp;
     byte *pic8;
     int  w,h;
{
  int   i,j,c,bitnum,padw;
  byte *pp;

  padw = ((w + 31)/32) * 32;  /* 'w', padded to be a multiple of 32 */

  for (i=h-1; i>=0; i--) {
    pp = pic8 + (i * w);  
    if ((i&0x3f)==0) WaitCursor();

    for (j=bitnum=c=0; j<=padw; j++,bitnum++) {
      if (bitnum == 8) { /* write the next byte */
	putc(c,fp);
	bitnum = c = 0;
      }
      
      c <<= 1;

      if (j<w) {
	c |= (pc2nc[*pp++] & 0x01);
      }
    }
  }
}  



/*******************************************/
static void writeBMP4(fp, pic8, w, h)
     FILE *fp;
     byte *pic8;
     int  w,h;
{
  int   i,j,c,nybnum,padw;
  byte *pp;


  padw = ((w + 7)/8) * 8; /* 'w' padded to a multiple of 8pix (32 bits) */

  for (i=h-1; i>=0; i--) {
    pp = pic8 + (i * w);
    if ((i&0x3f)==0) WaitCursor();

    for (j=nybnum=c=0; j<=padw; j++,nybnum++) {
      if (nybnum == 2) { /* write next byte */
	putc((c&0xff), fp);
	nybnum = c = 0;
      }

      c <<= 4;

      if (j<w) {
	c |= (pc2nc[*pp] & 0x0f);
	pp++;
      }
    }
  }
}  



/*******************************************/
static void writeBMP8(fp, pic8, w, h)
     FILE *fp;
     byte *pic8;
     int  w,h;
{
  int   i,j,c,padw;
  byte *pp;

  padw = ((w + 3)/4) * 4; /* 'w' padded to a multiple of 4pix (32 bits) */

  for (i=h-1; i>=0; i--) {
    pp = pic8 + (i * w);
    if ((i&0x3f)==0) WaitCursor();

    for (j=0; j<w; j++) putc(pc2nc[*pp++], fp);
    for ( ; j<padw; j++) putc(0, fp);
  }
}  


/*******************************************/
static void writeBMP24(fp, pic24, w, h)
     FILE *fp;
     byte *pic24;
     int  w,h;
{
  int   i,j,c,padb;
  byte *pp;

  padb = (4 - ((w*3) % 4)) & 0x03;  /* # of pad bytes to write at EOscanline */

  for (i=h-1; i>=0; i--) {
    pp = pic24 + (i * w * 3);
    if ((i&0x3f)==0) WaitCursor();

    for (j=0; j<w; j++) {
      putc(pp[2], fp);
      putc(pp[1], fp);
      putc(pp[0], fp);
      pp += 3;
    }

    for (j=0; j<padb; j++) putc(0, fp);
  }
}  






/*******************************************/
static int bmpError(fname, st)
     char *fname, *st;
{
  SetISTR(ISTR_WARNING,"%s:  %s", fname, st);
  return 0;
}