/* Copyright (C) 1991, 1996, 1997, 1998, 1999 Aladdin Enterprises.  All rights reserved.

   This file is part of Aladdin Ghostscript.

   Aladdin Ghostscript is distributed with NO WARRANTY OF ANY KIND.  No author
   or distributor accepts any responsibility for the consequences of using it,
   or for whether it serves any particular purpose or works at all, unless he
   or she says so in writing.  Refer to the Aladdin Ghostscript Free Public
   License (the "License") for full details.

   Every copy of Aladdin Ghostscript must include a copy of the License,
   normally in a plain ASCII text file named PUBLIC.  The License grants you
   the right to copy, modify and redistribute Aladdin Ghostscript, but only
   under certain conditions described in the License.  Among other things, the
   License requires that the copyright notice and this notice be preserved on
   all copies.
 */

/*$Id: sfilter2.c $ */
/* Simple Level 2 filters */
#include "stdio_.h"		/* includes std.h */
#include "memory_.h"
#include "gdebug.h"
#include "strimpl.h"
#include "sa85x.h"
#include "sbtx.h"
#include "scanchar.h"

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

private_st_A85E_state();

/* Initialize the state */
private int
s_A85E_init(stream_state * st)
{
    stream_A85E_state *const ss = (stream_A85E_state *) st;

    return s_A85E_init_inline(ss);
}

/* Process a buffer */
#define LINE_LIMIT 79		/* not 80, to satisfy Genoa FTS */
private int
s_A85E_process(stream_state * st, stream_cursor_read * pr,
	       stream_cursor_write * pw, bool last)
{
    stream_A85E_state *const ss = (stream_A85E_state *) st;
    register const byte *p = pr->ptr;
    register byte *q = pw->ptr;
    byte *qn = q + (LINE_LIMIT - ss->count); /* value of q before next EOL */
    const byte *rlimit = pr->limit;
    byte *wlimit = pw->limit;
    int status = 0;
    int count;

    if_debug3('w', "[w85]initial ss->count = %d, rcount = %d, wcount = %d\n",
	      ss->count, (int)(rlimit - p), (int)(wlimit - q));
    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 (q >= qn) {
		if (wlimit - q < 2) {
		    status = 1;
		    break;
		}
		*++q = '\n';
		qn = q + LINE_LIMIT;
		if_debug1('w', "[w85]EOL at %d bytes written\n",
			  (int)(q - pw->ptr));
	    } else {
		if (q >= wlimit) {
		    status = 1;
		    break;
		}
	    }
	    *++q = 'z';
	} else {
	    ulong v4 = word / 85;	/* max 85^4 */
	    ulong v3 = v4 / 85;	/* max 85^3 */
	    uint v2 = v3 / 85;	/* max 85^2 */
	    uint v1 = v2 / 85;	/* max 85 */

put:	    if (q + 5 > qn) {
		if (q >= wlimit) {
		    status = 1;
		    break;
		}
		*++q = '\n';
		qn = q + LINE_LIMIT;
		if_debug1('w', "[w85]EOL at %d bytes written\n",
			  (int)(q - pw->ptr));
		goto put;
	    }
	    if (wlimit - q < 5) {
		status = 1;
		break;
	    }
	    q[1] = (byte) v1 + '!';
	    q[2] = (byte) (v2 - v1 * 85) + '!';
	    q[3] = (byte) ((uint) v3 - v2 * 85) + '!';
	    q[4] = (byte) ((uint) v4 - (uint) v3 * 85) + '!';
	    q[5] = (byte) ((uint) word - (uint) v4 * 85) + '!';
	    /*
	     * Two consecutive '%' characters at the beginning
	     * of the line will confuse some document managers:
	     * insert (an) EOL(s) if necessary to prevent this.
	     */
	    if (q[1] == '%') {
		if (q == pw->ptr) {
		    /*
		     * The very first character written is a %.
		     * Add an EOL before it in case the last
		     * character of the previous batch was a %.
		     */
		    *++q = '\n';
		    qn = q + LINE_LIMIT;
		    if_debug1('w', "[w85]EOL at %d bytes written\n",
			      (int)(q - pw->ptr));
		    goto put;
		}
		if (q[2] == '%' && *q == '\n') {
		    /*
		     * We may have to insert more than one EOL if
		     * there are more than two %s in a row.
		     */
		    int extra =
			(q[3] != '%' ? 1 : q[4] != '%' ? 2 :
			 q[5] != '%' ? 3 : 4);

		    if (wlimit - q < 5 + extra) {
			status = 1;
			break;
		    }
		    switch (extra) {
			case 4:
			    q[9] = '%', q[8] = '\n';
			    goto e3;
			case 3:
			    q[8] = q[5];
			  e3:q[7] = '%', q[6] = '\n';
			    goto e2;
			case 2:
			    q[7] = q[5], q[6] = q[4];
			  e2:q[5] = '%', q[4] = '\n';
			    goto e1;
			case 1:
			    q[6] = q[5], q[5] = q[4], q[4] = q[3];
			  e1:q[3] = '%', q[2] = '\n';
		    }
		    if_debug1('w', "[w85]EOL at %d bytes written\n",
			      (int)(q + 2 * extra - pw->ptr));
		    qn = q + 2 * extra + LINE_LIMIT;
		    q += extra;
		}
	    }
	    q += 5;
	}
    }
 end:
    ss->count = LINE_LIMIT - (qn - q);
    /* Check for final partial word. */
    if (last && status == 0 && count < 4) {
	int nchars = (count == 0 ? 2 : count + 3);

	if (wlimit - q < nchars)
	    status = 1;
	else if (q + nchars > qn) {
	    *++q = '\n';
	    qn = q + LINE_LIMIT;
	    goto end;
	}
	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 = '>';
	}
    }
    if_debug3('w', "[w85]final ss->count = %d, %d bytes read, %d written\n",
	      ss->count, (int)(p - pr->ptr), (int)(q - pw->ptr));
    pr->ptr = p;
    pw->ptr = q;
    return status;
}
#undef LINE_LIMIT

/* Stream template */
const stream_template s_A85E_template = {
    &st_A85E_state, s_A85E_init, s_A85E_process, 4, 6
};

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

private_st_BT_state();

/* 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)
{
    stream_BT_state *const ss = (stream_BT_state *) st;
    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;
}

/* Stream template */
const stream_template s_BTE_template = {
    &st_BT_state, NULL, s_BT_process, 1, 1
};
const stream_template s_BTD_template = {
    &st_BT_state, NULL, s_BT_process, 1, 1
};
