1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * altera-comp.c
  4 *
  5 * altera FPGA driver
  6 *
  7 * Copyright (C) Altera Corporation 1998-2001
  8 * Copyright (C) 2010 NetUP Inc.
  9 * Copyright (C) 2010 Igor M. Liplianin <liplianin@netup.ru>
 10 */
 11
 12#include <linux/kernel.h>
 13#include "altera-exprt.h"
 14
 15#define	SHORT_BITS		16
 16#define	CHAR_BITS		8
 17#define	DATA_BLOB_LENGTH	3
 18#define	MATCH_DATA_LENGTH	8192
 19#define ALTERA_REQUEST_SIZE	1024
 20#define ALTERA_BUFFER_SIZE	(MATCH_DATA_LENGTH + ALTERA_REQUEST_SIZE)
 21
 22static u32 altera_bits_req(u32 n)
 23{
 24	u32 result = SHORT_BITS;
 25
 26	if (n == 0)
 27		result = 1;
 28	else {
 29		/* Look for the highest non-zero bit position */
 30		while ((n & (1 << (SHORT_BITS - 1))) == 0) {
 31			n <<= 1;
 32			--result;
 33		}
 34	}
 35
 36	return result;
 37}
 38
 39static u32 altera_read_packed(u8 *buffer, u32 bits, u32 *bits_avail,
 40							u32 *in_index)
 41{
 42	u32 result = 0;
 43	u32 shift = 0;
 44	u32 databyte = 0;
 45
 46	while (bits > 0) {
 47		databyte = buffer[*in_index];
 48		result |= (((databyte >> (CHAR_BITS - *bits_avail))
 49			& (0xff >> (CHAR_BITS - *bits_avail))) << shift);
 50
 51		if (bits <= *bits_avail) {
 52			result &= (0xffff >> (SHORT_BITS - (bits + shift)));
 53			*bits_avail -= bits;
 54			bits = 0;
 55		} else {
 56			++(*in_index);
 57			shift += *bits_avail;
 58			bits -= *bits_avail;
 59			*bits_avail = CHAR_BITS;
 60		}
 61	}
 62
 63	return result;
 64}
 65
 66u32 altera_shrink(u8 *in, u32 in_length, u8 *out, u32 out_length, s32 version)
 67{
 68	u32 i, j, data_length = 0L;
 69	u32 offset, length;
 70	u32 match_data_length = MATCH_DATA_LENGTH;
 71	u32 bits_avail = CHAR_BITS;
 72	u32 in_index = 0L;
 73
 74	if (version > 0)
 75		--match_data_length;
 76
 77	for (i = 0; i < out_length; ++i)
 78		out[i] = 0;
 79
 80	/* Read number of bytes in data. */
 81	for (i = 0; i < sizeof(in_length); ++i) {
 82		data_length = data_length | (
 83			altera_read_packed(in,
 84					CHAR_BITS,
 85					&bits_avail,
 86					&in_index) << (i * CHAR_BITS));
 87	}
 88
 89	if (data_length > out_length) {
 90		data_length = 0L;
 91		return data_length;
 92	}
 93
 94	i = 0;
 95	while (i < data_length) {
 96		/* A 0 bit indicates literal data. */
 97		if (altera_read_packed(in, 1, &bits_avail,
 98						&in_index) == 0) {
 99			for (j = 0; j < DATA_BLOB_LENGTH; ++j) {
100				if (i < data_length) {
101					out[i] = (u8)altera_read_packed(in,
102							CHAR_BITS,
103							&bits_avail,
104							&in_index);
105					i++;
106				}
107			}
108		} else {
109			/* A 1 bit indicates offset/length to follow. */
110			offset = altera_read_packed(in, altera_bits_req((s16)
111					(i > match_data_length ?
112						match_data_length : i)),
113					&bits_avail,
114					&in_index);
115			length = altera_read_packed(in, CHAR_BITS,
116					&bits_avail,
117					&in_index);
118			for (j = 0; j < length; ++j) {
119				if (i < data_length) {
120					out[i] = out[i - offset];
121					i++;
122				}
123			}
124		}
125	}
126
127	return data_length;
128}