/* Copyright (C) 1991, 1995 Aladdin Enterprises.  All rights reserved.
  
  This file is part of GNU Ghostscript.
  
  GNU Ghostscript is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY.  No author or distributor accepts responsibility to
  anyone for the consequences of using it or for whether it serves any
  particular purpose or works at all, unless he says so in writing.  Refer
  to the GNU Ghostscript General Public License for full details.
  
*/

/* sfilter2.c */
/* Simple Level 2 filters */
#include "stdio_.h"	/* includes std.h */
#include "memory_.h"
#include "strimpl.h"
#include "sbtx.h"
#include "sfilter.h"
#include "scanchar.h"

/* ------ ASCII85Encode ------ */

/* Process a buffer */
private int
s_A85E_process(stream_state *st, stream_cursor_read *pr,
  stream_cursor_write *pw, bool last)
{	register const byte *p = pr->ptr;
	register byte *q = pw->ptr;
	const byte *rlimit = pr->limit;
	byte *wlimit = pw->limit;
	int status = 0;
	int count;
	for ( ; (count = rlimit - p) >= 4; p += 4 )
	{	ulong word =
			((ulong)(((uint)p[1] << 8) + p[2]) << 16) +
			(((uint)p[3] << 8) + p[4]);
		if ( word == 0 )
		{	if ( wlimit - q < 2 )
			{	status = 1;
				break;
			}
			*++q = 'z';
		}
		else
		{	ulong v = word / (85L*85*85*85);  /* actually only a byte */
			ushort w1;
			if ( wlimit - q < 6 )
			{	status = 1;
				break;
			}
			q[1] = (byte)v + '!';
			word -= v * (85L*85*85*85);
			v = word / (85L*85*85);
			q[2] = (byte)v + '!';
			word -= v * (85L*85*85);
			v = word / (85*85);
			q[3] = (byte)v + '!';
			w1 = (ushort)(word - v * (85L*85));
			q[4] = (byte)(w1 / 85) + '!';
			q[5] = (byte)(w1 % 85) + '!';
			q += 5;
		}
		if ( !(count & 60) )
			*++q = '\n';
	}
	/* Check for final partial word. */
	if ( last && status == 0 && count < 4 )
	{	if ( wlimit - q < (count == 0 ? 2 : count + 3) )
			status = 1;
		else
		{	ulong word = 0;
			ulong divisor = 85L*85*85*85;
			switch ( count )
			{
			case 3:
				word += (uint)p[3] << 8;
			case 2:
				word += (ulong)p[2] << 16;
			case 1:
				word += (ulong)p[1] << 24;
				p += count;
				while ( count-- >= 0 )
				{	ulong v = word / divisor;  /* actually only a byte */
					*++q = (byte)v + '!';
					word -= v * divisor;
					divisor /= 85;
				}
			/*case 0:*/
			}
			*++q = '~';
			*++q = '>';
		}
	}
	pr->ptr = p;
	pw->ptr = q;
	return status;
}

/* Stream template */
const stream_template s_A85E_template =
{	&st_stream_state, NULL, s_A85E_process, 4, 6
};

/* ------ ASCII85Decode ------ */

private_st_A85D_state();

#define ss ((stream_A85D_state *)st)

/* Initialize the state */
private int
s_A85D_init(stream_state *st)
{	return s_A85D_init_inline(ss);
}

/* Process a buffer */
private int a85d_finish(P3(int, ulong, stream_cursor_write *));
private int
s_A85D_process(stream_state *st, stream_cursor_read *pr,
  stream_cursor_write *pw, bool last)
{	register const byte *p = pr->ptr;
	register byte *q = pw->ptr;
	const byte *rlimit = pr->limit;
	byte *wlimit = pw->limit;
	int ccount = ss->odd;
	ulong word = ss->word;
	int status = 0;
	while ( p < rlimit )
	{	int ch = *++p;
		uint ccode = ch - '!';
		if ( ccode < 85 )		/* catches ch < '!' as well */
		{	if ( wlimit - q < 4 )
			{	p--;
				status = 1;
				break;
			}
			word = word * 85 + ccode;
			if ( ++ccount == 5 )
			{	q[1] = word >> 24;
				q[2] = (byte)(word >> 16);
				q[3] = (byte)((uint)word >> 8);
				q[4] = (byte)word;
				q += 4;
				word = 0;
				ccount = 0;
			}
		}
		else if ( ch == 'z' && ccount == 0 )
		{	if ( wlimit - q < 4 )
			{	p--;
				status = 1;
				break;
			}
			q[1] = q[2] = q[3] = q[4] = 0,
			q += 4;
		}
		else if ( scan_char_decoder[ch] == ctype_space )
			;
		else if ( ch == '~' )
		{	/* Handle odd bytes. */
			if ( p == rlimit )
			{	if ( last )
				  status = ERRC;
				else
				  p--;
				break;
			}
			if ( (int)(wlimit - q) < ccount - 1 )
			{	status = 1;
				p--;
				break;
			}
			if ( *++p != '>' )
			{	status = ERRC;
				break;
			}
			pw->ptr = q;
			status = a85d_finish(ccount, word, pw);
			q = pw->ptr;
			break;
		}
		else			/* syntax error or exception */
		{	status = ERRC;
			break;
		}
	}
	pw->ptr = q;
	if ( status == 0 && last )
	{	if ( (int)(wlimit - q) < ccount - 1 )
		  status = 1;
		else
		  status = a85d_finish(ccount, word, pw);
	}
	pr->ptr = p;
	ss->odd = ccount;
	ss->word = word;
	return status;
}
/* Handle the end of input data. */
private int
a85d_finish(int ccount, ulong word, stream_cursor_write *pw)
{	/* Assume there is enough room in the output buffer! */
	byte *q = pw->ptr;
	int status = EOFC;
	switch ( ccount )
	{
	case 0:
		break;
	case 1:			/* syntax error */
		status = ERRC;
		break;
	case 2:			/* 1 odd byte */
		word = word * (85L*85*85) + 0xffffffL;
		goto o1;
	case 3:			/* 2 odd bytes */
		word = word * (85L*85) + 0xffffL;
		goto o2;
	case 4:			/* 3 odd bytes */
		word = word * 85 + 0xffL;
		q[3] = (byte)(word >> 8);
o2:		q[2] = (byte)(word >> 16);
o1:		q[1] = (byte)(word >> 24);
		q += ccount - 1;
		pw->ptr = q;
	}
	return status;
}

#undef ss

/* Stream template */
const stream_template s_A85D_template =
{	&st_A85D_state, s_A85D_init, s_A85D_process, 2, 4
};

/* ------ ByteTranslateEncode/Decode ------ */

private_st_BT_state();

#define ss ((stream_BT_state *)st)

/* Process a buffer.  Note that the same code serves for both streams. */

private int
s_BT_process(stream_state *st, stream_cursor_read *pr,
  stream_cursor_write *pw, bool last)
{	const byte *p = pr->ptr;
	byte *q = pw->ptr;
	uint rcount = pr->limit - p;
	uint wcount = pw->limit - q;
	uint count;
	int status;

	if ( rcount <= wcount )
	  count = rcount, status = 0;
	else
	  count = wcount, status = 1;

	while ( count-- )
	  *++q = ss->table[*++p];

	pr->ptr = p;
	pw->ptr = q;
	return status;
}

#undef ss

/* Stream template */

const stream_template s_BT_template =
{	&st_BT_state, NULL, s_BT_process, 1, 1
};