libgfortran/io/fbuf.c

   1 /* Copyright (C) 2008 Free Software Foundation, Inc.
   2    Contributed by Janne Blomqvist
   3
   4 This file is part of the GNU Fortran runtime library (libgfortran).
   5
   6 Libgfortran is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 In addition to the permissions in the GNU General Public License, the
  12 Free Software Foundation gives you unlimited permission to link the
  13 compiled version of this file into combinations with other programs,
  14 and to distribute those combinations without any restriction coming
  15 from the use of this file.  (The General Public License restrictions
  16 do apply in other respects; for example, they cover modification of
  17 the file, and distribution when not linked into a combine
  18 executable.)
  19
  20 Libgfortran is distributed in the hope that it will be useful,
  21 but WITHOUT ANY WARRANTY; without even the implied warranty of
  22 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  23 GNU General Public License for more details.
  24
  25 You should have received a copy of the GNU General Public License
  26 along with Libgfortran; see the file COPYING.  If not, write to
  27 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
  28 Boston, MA 02110-1301, USA.  */
  29
  30
  31 #include "io.h"
  32 #include <string.h>
  33 #include <stdlib.h>
  34
  35
  36 void
  37 fbuf_init (gfc_unit * u, size_t len)
  38 {
  39   if (len == 0)
  40     len = 512;                  /* Default size.  */
  41
  42   u->fbuf = get_mem (sizeof (fbuf));
  43   u->fbuf->buf = get_mem (len);
  44   u->fbuf->len = len;
  45   u->fbuf->act = u->fbuf->flushed = u->fbuf->pos = 0;
  46 }
  47
  48
  49 void
  50 fbuf_reset (gfc_unit * u)
  51 {
  52   u->fbuf->act = u->fbuf->flushed = u->fbuf->pos = 0;
  53 }
  54
  55
  56 void
  57 fbuf_destroy (gfc_unit * u)
  58 {
  59   if (u->fbuf == NULL)
  60     return;
  61   if (u->fbuf->buf)
  62     free_mem (u->fbuf->buf);
  63   free_mem (u->fbuf);
  64 }
  65
  66
  67 /* Return a pointer to the current position in the buffer, and increase
  68    the pointer by len. Makes sure that the buffer is big enough,
  69    reallocating if necessary. If the buffer is not big enough, there are
  70    three cases to consider:
  71    1. If we haven't flushed anything, realloc
  72    2. If we have flushed enough that by discarding the flushed bytes
  73       the request fits into the buffer, do that.
  74    3. Else allocate a new buffer, memcpy unflushed active bytes from old
  75       buffer. */
  76
  77 char *
  78 fbuf_alloc (gfc_unit * u, size_t len)
  79 {
  80   size_t newlen;
  81   char *dest;
  82   if (u->fbuf->pos + len > u->fbuf->len)
  83     {
  84       if (u->fbuf->flushed == 0)
  85         {
  86           /* Round up to nearest multiple of the current buffer length.  */
  87           newlen = ((u->fbuf->pos + len) / u->fbuf->len + 1) * u->fbuf->len;
  88           dest = realloc (u->fbuf->buf, newlen);
  89           if (dest == NULL)
  90             return NULL;
  91           u->fbuf->buf = dest;
  92           u->fbuf->len = newlen;
  93         }
  94       else if (u->fbuf->act - u->fbuf->flushed + len < u->fbuf->len)
  95         {
  96           memmove (u->fbuf->buf, u->fbuf->buf + u->fbuf->flushed,
  97                    u->fbuf->act - u->fbuf->flushed);
  98           u->fbuf->act -= u->fbuf->flushed;
  99           u->fbuf->pos -= u->fbuf->flushed;
 100           u->fbuf->flushed = 0;
 101         }
 102       else
 103         {
 104           /* Most general case, flushed != 0, request doesn't fit.  */
 105           newlen = ((u->fbuf->pos - u->fbuf->flushed + len)
 106                     / u->fbuf->len + 1) * u->fbuf->len;
 107           dest = get_mem (newlen);
 108           memcpy (dest, u->fbuf->buf + u->fbuf->flushed,
 109                   u->fbuf->act - u->fbuf->flushed);
 110           u->fbuf->act -= u->fbuf->flushed;
 111           u->fbuf->pos -= u->fbuf->flushed;
 112           u->fbuf->flushed = 0;
 113           u->fbuf->buf = dest;
 114           u->fbuf->len = newlen;
 115         }
 116     }
 117
 118   dest = u->fbuf->buf + u->fbuf->pos;
 119   u->fbuf->pos += len;
 120   if (u->fbuf->pos > u->fbuf->act)
 121     u->fbuf->act = u->fbuf->pos;
 122   return dest;
 123 }
 124
 125
 126
 127
 128 int
 129 fbuf_flush (gfc_unit * u, int record_done)
 130 {
 131   int status;
 132   size_t nbytes;
 133
 134   if (!u->fbuf)
 135     return 0;
 136   if (u->fbuf->act - u->fbuf->flushed != 0)
 137     {
 138       if (record_done)
 139         nbytes = u->fbuf->act - u->fbuf->flushed;
 140       else
 141         nbytes = u->fbuf->pos - u->fbuf->flushed;
 142       status = swrite (u->s, u->fbuf->buf + u->fbuf->flushed, &nbytes);
 143       u->fbuf->flushed += nbytes;
 144     }
 145   else
 146     status = 0;
 147   if (record_done)
 148     fbuf_reset (u);
 149   return status;
 150 }
 151
 152
 153 int
 154 fbuf_seek (gfc_unit * u, gfc_offset off)
 155 {
 156   gfc_offset pos = u->fbuf->pos + off;
 157   /* Moving to the left past the flushed marked would imply moving past
 158      the left tab limit, which is never allowed. So return error if
 159      that is attempted.  */
 160   if (pos < u->fbuf->flushed)
 161     return -1;
 162   u->fbuf->pos = pos;
 163   return 0;
 164 }