/* Copyright (c) 2010 MJ Rutter 
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation.
 * 
 * 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., 51 Franklin Street,
 * Fifth Floor, Boston, MA  02110-1301, USA.
 */ 

/* print a string ASCII85 encoded
 * MJR 4/01, 5/02
 */

#include<stdio.h>

/* Number of raw bytes to encode per line. Note actual line length will
 * be 1.25x this.  Sane values are 56 (70 characters) or 60 (75 chars) */
#define LINELEN 56 /* must be multiple of 4 */

unsigned int A85p(FILE* fout, unsigned char* in,int len)
{
  int i,j;
  unsigned int tmp,t,line,length=0;
  unsigned int pow85[] = {52200625,614125,7225,85,1}; /* powers of 85 */
  unsigned char out[LINELEN/4*5+4],*outp;

  while (len>0){
    line=(len>LINELEN) ? LINELEN : len;
    len=len-line;
    outp=out;
    for(i=0;i<(line&0xfffc);i+=4){ /* encode groups of four bytes */
      tmp=0;
      for(j=0;j<4;j++){
	tmp=tmp<<8;
	tmp+=*(in++);
      }
      if (tmp){
	for(j=0;j<4;j++){
	  t=tmp/pow85[j];
	  tmp-=t*pow85[j];
	  *(outp++)=t+'!';
	}
	*(outp++)=tmp+'!';
      }
      else
	*(outp++)='z';       /* zero is encoded as "z", not "!!!!!" */
    }
    
    if (line&0x3){          /* Deal with any final group of <4 bytes */
      i=line&0xfffc;
      tmp=0;
      for(j=0;j<4;j++){
	tmp=tmp<<8;
	if ((i+j)<line) tmp+=*(in++);
      }
      for(j=0;j<((line&0x3)+1);j++){
	t=tmp/pow85[j];
	tmp-=t*pow85[j];
	*(outp++)=t+'!';
      }
    }

    *outp=0;
/* Assist things which parse DSC comments by ensuring that any line which
 * would start %! or %% has a space prefixed.
 */
    if ((out[0]=='%')&&((out[1]=='%')||(out[1]=='!')))
      length+=fprintf(fout," %s\n",out);
    else length+=fprintf(fout,"%s\n",out);
  }

  length+=fprintf(fout,"~>\n");

  return length;

}