1/*
  2 * altera-comp.c
  3 *
  4 * altera FPGA driver
  5 *
  6 * Copyright (C) Altera Corporation 1998-2001
  7 * Copyright (C) 2010 NetUP Inc.
  8 * Copyright (C) 2010 Igor M. Liplianin <liplianin@netup.ru>
  9 *
 10 * This program is free software; you can redistribute it and/or modify
 11 * it under the terms of the GNU General Public License as published by
 12 * the Free Software Foundation; either version 2 of the License, or
 13 * (at your option) any later version.
 14 *
 15 * This program is distributed in the hope that it will be useful,
 16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 18 *
 19 * GNU General Public License for more details.
 20 *
 21 * You should have received a copy of the GNU General Public License
 22 * along with this program; if not, write to the Free Software
 23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 24 */
 25
 26#include <linux/kernel.h>
 27#include "altera-exprt.h"
 28
 29#define	SHORT_BITS		16
 30#define	CHAR_BITS		8
 31#define	DATA_BLOB_LENGTH	3
 32#define	MATCH_DATA_LENGTH	8192
 33#define ALTERA_REQUEST_SIZE	1024
 34#define ALTERA_BUFFER_SIZE	(MATCH_DATA_LENGTH + ALTERA_REQUEST_SIZE)
 35
 36static u32 altera_bits_req(u32 n)
 37{
 38	u32 result = SHORT_BITS;
 39
 40	if (n == 0)
 41		result = 1;
 42	else {
 43		/* Look for the highest non-zero bit position */
 44		while ((n & (1 << (SHORT_BITS - 1))) == 0) {
 45			n <<= 1;
 46			--result;
 47		}
 48	}
 49
 50	return result;
 51}
 52
 53static u32 altera_read_packed(u8 *buffer, u32 bits, u32 *bits_avail,
 54							u32 *in_index)
 55{
 56	u32 result = 0;
 57	u32 shift = 0;
 58	u32 databyte = 0;
 59
 60	while (bits > 0) {
 61		databyte = buffer[*in_index];
 62		result |= (((databyte >> (CHAR_BITS - *bits_avail))
 63			& (0xff >> (CHAR_BITS - *bits_avail))) << shift);
 64
 65		if (bits <= *bits_avail) {
 66			result &= (0xffff >> (SHORT_BITS - (bits + shift)));
 67			*bits_avail -= bits;
 68			bits = 0;
 69		} else {
 70			++(*in_index);
 71			shift += *bits_avail;
 72			bits -= *bits_avail;
 73			*bits_avail = CHAR_BITS;
 74		}
 75	}
 76
 77	return result;
 78}
 79
 80u32 altera_shrink(u8 *in, u32 in_length, u8 *out, u32 out_length, s32 version)
 81{
 82	u32 i, j, data_length = 0L;
 83	u32 offset, length;
 84	u32 match_data_length = MATCH_DATA_LENGTH;
 85	u32 bits_avail = CHAR_BITS;
 86	u32 in_index = 0L;
 87
 88	if (version > 0)
 89		--match_data_length;
 90
 91	for (i = 0; i < out_length; ++i)
 92		out[i] = 0;
 93
 94	/* Read number of bytes in data. */
 95	for (i = 0; i < sizeof(in_length); ++i) {
 96		data_length = data_length | (
 97			altera_read_packed(in,
 98					CHAR_BITS,
 99					&bits_avail,
100					&in_index) << (i * CHAR_BITS));
101	}
102
103	if (data_length > out_length) {
104		data_length = 0L;
105		return data_length;
106	}
107
108	i = 0;
109	while (i < data_length) {
110		/* A 0 bit indicates literal data. */
111		if (altera_read_packed(in, 1, &bits_avail,
112						&in_index) == 0) {
113			for (j = 0; j < DATA_BLOB_LENGTH; ++j) {
114				if (i < data_length) {
115					out[i] = (u8)altera_read_packed(in,
116							CHAR_BITS,
117							&bits_avail,
118							&in_index);
119					i++;
120				}
121			}
122		} else {
123			/* A 1 bit indicates offset/length to follow. */
124			offset = altera_read_packed(in, altera_bits_req((s16)
125					(i > match_data_length ?
126						match_data_length : i)),
127					&bits_avail,
128					&in_index);
129			length = altera_read_packed(in, CHAR_BITS,
130					&bits_avail,
131					&in_index);
132			for (j = 0; j < length; ++j) {
133				if (i < data_length) {
134					out[i] = out[i - offset];
135					i++;
136				}
137			}
138		}
139	}
140
141	return data_length;
142}