ewah/ewah_io.c

   1 /**
   2  * Copyright 2013, GitHub, Inc
   3  * Copyright 2009-2013, Daniel Lemire, Cliff Moon,
   4  *      David McIntosh, Robert Becho, Google Inc. and Veronika Zenz
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version 2
   9  * of the License, or (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #define DISABLE_SIGN_COMPARE_WARNINGS
  21
  22 #include "git-compat-util.h"
  23 #include "ewok.h"
  24 #include "strbuf.h"
  25
  26 int ewah_serialize_to(struct ewah_bitmap *self,
  27                       int (*write_fun)(void *, const void *, size_t),
  28                       void *data)
  29 {
  30         size_t i;
  31         eword_t dump[2048];
  32         const size_t words_per_dump = sizeof(dump) / sizeof(eword_t);
  33         uint32_t bitsize, word_count, rlw_pos;
  34
  35         const eword_t *buffer;
  36         size_t words_left;
  37
  38         /* 32 bit -- bit size for the map */
  39         bitsize =  htonl((uint32_t)self->bit_size);
  40         if (write_fun(data, &bitsize, 4) != 4)
  41                 return -1;
  42
  43         /** 32 bit -- number of compressed 64-bit words */
  44         word_count =  htonl((uint32_t)self->buffer_size);
  45         if (write_fun(data, &word_count, 4) != 4)
  46                 return -1;
  47
  48         /** 64 bit x N -- compressed words */
  49         buffer = self->buffer;
  50         words_left = self->buffer_size;
  51
  52         while (words_left >= words_per_dump) {
  53                 for (i = 0; i < words_per_dump; ++i, ++buffer)
  54                         dump[i] = htonll(*buffer);
  55
  56                 if (write_fun(data, dump, sizeof(dump)) != sizeof(dump))
  57                         return -1;
  58
  59                 words_left -= words_per_dump;
  60         }
  61
  62         if (words_left) {
  63                 for (i = 0; i < words_left; ++i, ++buffer)
  64                         dump[i] = htonll(*buffer);
  65
  66                 if (write_fun(data, dump, words_left * 8) != words_left * 8)
  67                         return -1;
  68         }
  69
  70         /** 32 bit -- position for the RLW */
  71         rlw_pos = (uint8_t*)self->rlw - (uint8_t *)self->buffer;
  72         rlw_pos = htonl(rlw_pos / sizeof(eword_t));
  73
  74         if (write_fun(data, &rlw_pos, 4) != 4)
  75                 return -1;
  76
  77         return (3 * 4) + (self->buffer_size * 8);
  78 }
  79
  80 static int write_strbuf(void *user_data, const void *data, size_t len)
  81 {
  82         struct strbuf *sb = user_data;
  83         strbuf_add(sb, data, len);
  84         return len;
  85 }
  86
  87 int ewah_serialize_strbuf(struct ewah_bitmap *self, struct strbuf *sb)
  88 {
  89         return ewah_serialize_to(self, write_strbuf, sb);
  90 }
  91
  92 ssize_t ewah_read_mmap(struct ewah_bitmap *self, const void *map, size_t len)
  93 {
  94         const uint8_t *ptr = map;
  95         size_t data_len;
  96         size_t i;
  97
  98         if (len < sizeof(uint32_t))
  99                 return error("corrupt ewah bitmap: eof before bit size");
 100         self->bit_size = get_be32(ptr);
 101         ptr += sizeof(uint32_t);
 102         len -= sizeof(uint32_t);
 103
 104         if (len < sizeof(uint32_t))
 105                 return error("corrupt ewah bitmap: eof before length");
 106         self->buffer_size = self->alloc_size = get_be32(ptr);
 107         ptr += sizeof(uint32_t);
 108         len -= sizeof(uint32_t);
 109
 110         REALLOC_ARRAY(self->buffer, self->alloc_size);
 111
 112         /*
 113          * Copy the raw data for the bitmap as a whole chunk;
 114          * if we're in a little-endian platform, we'll perform
 115          * the endianness conversion in a separate pass to ensure
 116          * we're loading 8-byte aligned words.
 117          */
 118         data_len = st_mult(self->buffer_size, sizeof(eword_t));
 119         if (len < data_len)
 120                 return error("corrupt ewah bitmap: eof in data "
 121                              "(%"PRIuMAX" bytes short)",
 122                              (uintmax_t)(data_len - len));
 123         memcpy(self->buffer, ptr, data_len);
 124         ptr += data_len;
 125         len -= data_len;
 126
 127         for (i = 0; i < self->buffer_size; ++i)
 128                 self->buffer[i] = ntohll(self->buffer[i]);
 129
 130         if (len < sizeof(uint32_t))
 131                 return error("corrupt ewah bitmap: eof before rlw");
 132         self->rlw = self->buffer + get_be32(ptr);
 133         ptr += sizeof(uint32_t);
 134         len -= sizeof(uint32_t);
 135
 136         return ptr - (const uint8_t *)map;
 137 }