path: root/filter/faxd.c

#include <fitz.h>

#include "faxd.h"
#include "faxc.h"

enum
{
	SNORMAL,	/* neutral state, waiting for any code */
	SMAKEUP,	/* got a 1d makeup code, waiting for terminating code */
	SEOL,		/* at eol, needs output buffer space */
	SH1, SH2	/* in H part 1 and 2 (both makeup and terminating codes) */
};

#define DEBUG 1

#ifdef noDEBUG
#define DPRINT(...) fprintf(stderr, __VA_ARGS__)
#else
#define DPRINT(...)
#endif

/* TODO: uncompressed */

typedef struct fz_faxd_s fz_faxd;

struct fz_faxd_s
{
	fz_filter super;
	
	int k;
	int endofline;
	int encodedbytealign;
	int columns;
	int rows;
	int endofblock;
	int blackis1;

	int stride;
	int ridx;

	int bidx;
	unsigned int word;

	int stage, a, c, dim, eolc;
	unsigned char *ref;
	unsigned char *dst;
};

fz_error *
fz_newfaxd(fz_filter **fp, fz_obj *params)
{
	fz_obj *obj;

	FZ_NEWFILTER(fz_faxd, fax, faxd);

	fax->ref = nil;
	fax->dst = nil;

	fax->k = 0;
	fax->endofline = 0;
	fax->encodedbytealign = 0;
	fax->columns = 1728;
	fax->rows = 0;
	fax->endofblock = 1;
	fax->blackis1 = 0;

	obj = fz_dictgets(params, "K");
	if (obj) fax->k = fz_toint(obj);

	obj = fz_dictgets(params, "EndOfLine");
	if (obj) fax->endofline = fz_tobool(obj);

	obj = fz_dictgets(params, "EncodedByteAlign");
	if (obj) fax->encodedbytealign = fz_tobool(obj);

	obj = fz_dictgets(params, "Columns");
	if (obj) fax->columns = fz_toint(obj);

	obj = fz_dictgets(params, "Rows");
	if (obj) fax->rows = fz_toint(obj);

	obj = fz_dictgets(params, "EndOfBlock");
	if (obj) fax->endofblock = fz_tobool(obj);

	obj = fz_dictgets(params, "BlackIs1");
	if (obj) fax->blackis1 = fz_tobool(obj);

	fax->stride = ((fax->columns - 1) >> 3) + 1;
	fax->ridx = 0;
	fax->bidx = 32;
	fax->word = 0;

	fax->stage = SNORMAL;
	fax->a = -1;
	fax->c = 0;
	fax->dim = fax->k < 0 ? 2 : 1;
	fax->eolc = 0;

	fax->ref = fz_malloc(fax->stride);
	if (!fax->ref) { fz_free(fax); return fz_outofmem; }

	fax->dst = fz_malloc(fax->stride);
	if (!fax->dst) { fz_free(fax); fz_free(fax->ref); return fz_outofmem; }

	memset(fax->ref, 0, fax->stride);
	memset(fax->dst, 0, fax->stride);

	DPRINT("FAXD k=%d eol=%d eba=%d cols=%d rows=%d eob=%d black1=%d stride=%d\n",
		fax->k, fax->endofline, fax->encodedbytealign,
		fax->columns, fax->rows, fax->endofblock, fax->blackis1,
		fax->stride);

	return nil;
}

void
fz_dropfaxd(fz_filter *p)
{
	fz_faxd *fax = (fz_faxd*) p;
	fz_free(fax->ref);
	fz_free(fax->dst);
}

static inline void eatbits(fz_faxd *fax, int nbits)
{
	fax->word <<= nbits;
	fax->bidx += nbits;
}

static inline fz_error * fillbits(fz_faxd *fax, fz_buffer *in)
{
	while (fax->bidx >= 8)
	{
		if (in->rp + 1 > in->wp)
			return fz_ioneedin;
		fax->bidx -= 8;
		fax->word |= *in->rp << fax->bidx;
		in->rp ++;
	}
	return nil;
}

static int
getcode(fz_faxd *fax, const cfd_node *table, int initialbits)
{
	unsigned int word = fax->word;
	int tidx = word >> (32 - initialbits);
	int val = table[tidx].val;
	int nbits = table[tidx].nbits;

	if (nbits > initialbits)
	{
		int mask = (1 << (32 - initialbits)) - 1;
		tidx = val + ((word & mask) >> (32 - nbits));
		val = table[tidx].val;
		nbits = initialbits + table[tidx].nbits;
	}

	eatbits(fax, nbits);

	return val;
}

/* decode one 1d code */
static fz_error *
dec1d(fz_faxd *fax)
{
	int code;

	if (fax->a == -1)
		fax->a = 0;

	if (fax->c)
		code = getcode(fax, cf_black_decode, cfd_black_initial_bits);
	else
		code = getcode(fax, cf_white_decode, cfd_white_initial_bits);

	DPRINT("%c %d\n", fax->c?'b':'w', code);

	if (code == UNCOMPRESSED)
		return fz_throw("ioerror: uncompressed data in faxd");

	if (code < 0)
		return fz_throw("ioerror: invalid 1d code in faxd");

	if (fax->a + code > fax->columns)
		return fz_throw("ioerror: invalid 1d data in faxd");

	if (fax->c)
		setbits(fax->dst, fax->a, fax->a + code);

	fax->a += code;

	if (code < 64)
	{
		fax->c = !fax->c;
		fax->stage = SNORMAL;
	}
	else
		fax->stage = SMAKEUP;

	return nil;
}

/* decode one 2d code */
static fz_error *
dec2d(fz_faxd *fax)
{
	int code, b1, b2;

	if (fax->stage == SH1 || fax->stage == SH2)
	{
		if (fax->a == -1)
			fax->a = 0;

		if (fax->c)
			code = getcode(fax, cf_black_decode, cfd_black_initial_bits);
		else
			code = getcode(fax, cf_white_decode, cfd_white_initial_bits);

		DPRINT("%c %d\n", fax->c ? 'b' : 'w', code);

		if (code == UNCOMPRESSED)
			return fz_throw("ioerror: uncompressed data in faxd");

		if (code < 0)
			return fz_throw("ioerror: invalid 2d code in faxd");

		if (fax->a + code > fax->columns)
			return fz_throw("ioerror: invalid 2d data in faxd");

		if (fax->c)
			setbits(fax->dst, fax->a, fax->a + code);

		fax->a += code;

		if (code < 64)
		{
			fax->c = !fax->c;
			if (fax->stage == SH1)
				fax->stage = SH2;
			else if (fax->stage == SH2)
				fax->stage = SNORMAL;
		}

		return nil;
	}

	code = getcode(fax, cf_2d_decode, cfd_2d_initial_bits);

	switch (code)
	{
		case H:
			fax->stage = SH1;
			DPRINT("H\n");
			break;

		case P:
			b1 = findchangingcolor(fax->ref, fax->a, fax->columns, !fax->c);
			b2 = findchanging(fax->ref, b1, fax->columns);
			DPRINT("P\n");
			if (fax->c) setbits(fax->dst, fax->a, b2);
			fax->a = b2;
			break;

		case V0:
			b1 = findchangingcolor(fax->ref, fax->a, fax->columns, !fax->c);
			DPRINT("V0\n");
			if (fax->c) setbits(fax->dst, fax->a, b1);
			fax->a = b1;
			fax->c = !fax->c;
			break;

		case VR1:
			b1 = findchangingcolor(fax->ref, fax->a, fax->columns, !fax->c);
			DPRINT("VR1\n");
			if (fax->c) setbits(fax->dst, fax->a, b1 + 1);
			fax->a = b1 + 1;
			fax->c = !fax->c;
			break;

		case VR2:
			b1 = findchangingcolor(fax->ref, fax->a, fax->columns, !fax->c);
			DPRINT("VR2\n");
			if (fax->c) setbits(fax->dst, fax->a, b1 + 2);
			fax->a = b1 + 2;
			fax->c = !fax->c;
			break;

		case VR3:
			b1 = findchangingcolor(fax->ref, fax->a, fax->columns, !fax->c);
			DPRINT("VR3\n");
			if (fax->c) setbits(fax->dst, fax->a, b1 + 3);
			fax->a = b1 + 3;
			fax->c = !fax->c;
			break;

		case VL1:
			b1 = findchangingcolor(fax->ref, fax->a, fax->columns, !fax->c);
			DPRINT("VL1\n");
			if (fax->c) setbits(fax->dst, fax->a, b1 - 1);
			fax->a = b1 - 1;
			fax->c = !fax->c;
			break;

		case VL2:
			b1 = findchangingcolor(fax->ref, fax->a, fax->columns, !fax->c);
			DPRINT("VL2\n");
			if (fax->c) setbits(fax->dst, fax->a, b1 - 2);
			fax->a = b1 - 2;
			fax->c = !fax->c;
			break;

		case VL3:
			b1 = findchangingcolor(fax->ref, fax->a, fax->columns, !fax->c);
			DPRINT("VL3\n");
			if (fax->c) setbits(fax->dst, fax->a, b1 - 3);
			fax->a = b1 - 3;
			fax->c = !fax->c;
			break;

		case UNCOMPRESSED:
			return fz_throw("ioerror: uncompressed data in faxd");

		case ERROR:
			return fz_throw("ioerror: invalid 2d code in faxd");

		default:
			return fz_throw("ioerror: invalid 2d code in faxd (%d)", code);
	}

	return 0;
}

fz_error *
fz_processfaxd(fz_filter *f, fz_buffer *in, fz_buffer *out)
{
	fz_faxd *fax = (fz_faxd*)f;
	fz_error * err;
	int i;

	if (fax->stage == SEOL)
		goto eol;

loop:

	if (fillbits(fax, in))
	{
		if (in->eof) {
			if (fax->bidx > 31) {
				if (fax->a > 0)
					goto eol;
				goto rtc;
			}
		}
		else {
			return fz_ioneedin;
		}
	}

	if ((fax->word >> (32 - 12)) == 0)
	{
		eatbits(fax, 1);
		goto loop;
	}

	if ((fax->word >> (32 - 12)) == 1)
	{
		DPRINT("EOL\n");
		eatbits(fax, 12);
		fax->eolc ++;

		if (fax->k > 0) {
			if ((fax->word >> (32 - 1)) == 1)
				fax->dim = 1;
			else
				fax->dim = 2;
			eatbits(fax, 1);
			DPRINT("DIM %d\n", fax->dim);
		}
	}
	else if (fax->dim == 1)
	{
		fax->eolc = 0;
		err = dec1d(fax);
		if (err) return err;

	}
	else if (fax->dim == 2)
	{
		fax->eolc = 0;
		err = dec2d(fax);
		if (err) return err;
	}

	/* no eol check after makeup codes nor in the middle of an H code */
	if (fax->stage == SMAKEUP || fax->stage == SH1 || fax->stage == SH2)
		goto loop;

	/* check for eol conditions */
	if (fax->eolc || fax->a >= fax->columns)
	{
		if (fax->a > 0)
			goto eol;
		if (fax->eolc == (fax->k < 0 ? 2 : 6))
			goto rtc;
	}

	goto loop;

eol:
	fax->stage = SEOL;
	if (out->wp + fax->stride > out->ep)
		return fz_ioneedout;

	if (fax->blackis1)
		memcpy(out->wp, fax->dst, fax->stride);
	else
		for (i = 0; i < fax->stride; i++)
			out->wp[i] = ~fax->dst[i];

	memcpy(fax->ref, fax->dst, fax->stride);
	memset(fax->dst, 0, fax->stride);
	out->wp += fax->stride;

	fax->stage = SNORMAL;
	fax->c = 0;
	fax->a = -1;
	fax->ridx ++;

	if (!fax->endofblock && fax->rows) {
		if (fax->ridx >= fax->rows)
			goto rtc;
	}

	/* we have not read dim from eol, make a guess */
	if (fax->k > 0 && !fax->eolc)
	{
		if (fax->ridx % fax->k == 0)
			fax->dim = 1;
		else
			fax->dim = 2;
	}

	DPRINT("%dd scanline %d\n", fax->dim, fax->ridx + 1);

	/* if endofline & encodedbytealign, EOLs are *not* optional */
	if (fax->encodedbytealign) {
		if (fax->endofline)
			eatbits(fax, (12 - fax->bidx) & 7);
		else
			eatbits(fax, (8 - fax->bidx) & 7);
	}

	goto loop;

rtc:
	DPRINT("RTC\n");
	out->eof = 1;
	return fz_iodone;
}