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 #include "git-compat-util.h"
  20 #include "ewok.h"
  21 #include "strbuf.h"
  22
  23 int ewah_serialize_to(struct ewah_bitmap *self,
  24                       int (*write_fun)(void *, const void *, size_t),
  25                       void *data)
  26 {
  27         size_t i;
  28         eword_t dump[2048];
  29         const size_t words_per_dump = sizeof(dump) / sizeof(eword_t);
  30         uint32_t bitsize, word_count, rlw_pos;
  31
  32         const eword_t *buffer;
  33         size_t words_left;
  34
  35         /* 32 bit -- bit size for the map */
  36         bitsize =  htonl((uint32_t)self->bit_size);
  37         if (write_fun(data, &bitsize, 4) != 4)
  38                 return -1;
  39
  40         /** 32 bit -- number of compressed 64-bit words */
  41         word_count =  htonl((uint32_t)self->buffer_size);
  42         if (write_fun(data, &word_count, 4) != 4)
  43                 return -1;
  44
  45         /** 64 bit x N -- compressed words */
  46         buffer = self->buffer;
  47         words_left = self->buffer_size;
  48
  49         while (words_left >= words_per_dump) {
  50                 for (i = 0; i < words_per_dump; ++i, ++buffer)
  51                         dump[i] = htonll(*buffer);
  52
  53                 if (write_fun(data, dump, sizeof(dump)) != sizeof(dump))
  54                         return -1;
  55
  56                 words_left -= words_per_dump;
  57         }
  58
  59         if (words_left) {
  60                 for (i = 0; i < words_left; ++i, ++buffer)
  61                         dump[i] = htonll(*buffer);
  62
  63                 if (write_fun(data, dump, words_left * 8) != words_left * 8)
  64                         return -1;
  65         }
  66
  67         /** 32 bit -- position for the RLW */
  68         rlw_pos = (uint8_t*)self->rlw - (uint8_t *)self->buffer;
  69         rlw_pos = htonl(rlw_pos / sizeof(eword_t));
  70
  71         if (write_fun(data, &rlw_pos, 4) != 4)
  72                 return -1;
  73
  74         return (3 * 4) + (self->buffer_size * 8);
  75 }
  76
  77 static int write_strbuf(void *user_data, const void *data, size_t len)
  78 {
  79         struct strbuf *sb = user_data;
  80         strbuf_add(sb, data, len);
  81         return len;
  82 }
  83
  84 int ewah_serialize_strbuf(struct ewah_bitmap *self, struct strbuf *sb)
  85 {
  86         return ewah_serialize_to(self, write_strbuf, sb);
  87 }
  88
  89 ssize_t ewah_read_mmap(struct ewah_bitmap *self, const void *map, size_t len)
  90 {
  91         const uint8_t *ptr = map;
  92         size_t data_len;
  93         size_t i;
  94
  95         if (len < sizeof(uint32_t))
  96                 return error("corrupt ewah bitmap: eof before bit size");
  97         self->bit_size = get_be32(ptr);
  98         ptr += sizeof(uint32_t);
  99         len -= sizeof(uint32_t);
 100
 101         if (len < sizeof(uint32_t))
 102                 return error("corrupt ewah bitmap: eof before length");
 103         self->buffer_size = self->alloc_size = get_be32(ptr);
 104         ptr += sizeof(uint32_t);
 105         len -= sizeof(uint32_t);
 106
 107         REALLOC_ARRAY(self->buffer, self->alloc_size);
 108
 109         /*
 110          * Copy the raw data for the bitmap as a whole chunk;
 111          * if we're in a little-endian platform, we'll perform
 112          * the endianness conversion in a separate pass to ensure
 113          * we're loading 8-byte aligned words.
 114          */
 115         data_len = st_mult(self->buffer_size, sizeof(eword_t));
 116         if (len < data_len)
 117                 return error("corrupt ewah bitmap: eof in data "
 118                              "(%"PRIuMAX" bytes short)",
 119                              (uintmax_t)(data_len - len));
 120         memcpy(self->buffer, ptr, data_len);
 121         ptr += data_len;
 122         len -= data_len;
 123
 124         for (i = 0; i < self->buffer_size; ++i)
 125                 self->buffer[i] = ntohll(self->buffer[i]);
 126
 127         if (len < sizeof(uint32_t))
 128                 return error("corrupt ewah bitmap: eof before rlw");
 129         self->rlw = self->buffer + get_be32(ptr);
 130         ptr += sizeof(uint32_t);
 131         len -= sizeof(uint32_t);
 132
 133         return ptr - (const uint8_t *)map;
 134 }