drivers/misc/altera-stapl/altera-comp.c

   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
  36 static 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
  53 static 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
  80 u32 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 }