code.delx.au - pulseaudio/blob - src/polypcore/mcalign.c

   1 /* $Id$ */
   2
   3 /***
   4   This file is part of polypaudio.
   5
   6   polypaudio is free software; you can redistribute it and/or modify
   7   it under the terms of the GNU Lesser General Public License as
   8   published by the Free Software Foundation; either version 2.1 of the
   9   License, or (at your option) any later version.
  10
  11   polypaudio is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public
  17   License along with polypaudio; if not, write to the Free Software
  18   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  19   USA.
  20 ***/
  21
  22 #ifdef HAVE_CONFIG_H
  23 #include <config.h>
  24 #endif
  25
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <assert.h>
  29 #include <string.h>
  30
  31 #include "mcalign.h"
  32 #include "xmalloc.h"
  33
  34 struct pa_mcalign {
  35     size_t base;
  36     pa_memchunk leftover, current;
  37     pa_memblock_stat *memblock_stat;
  38 };
  39
  40 pa_mcalign *pa_mcalign_new(size_t base, pa_memblock_stat *s) {
  41     pa_mcalign *m;
  42     assert(base);
  43
  44     m = pa_xnew(pa_mcalign, 1);
  45     m->base = base;
  46     pa_memchunk_reset(&m->leftover);
  47     pa_memchunk_reset(&m->current);
  48     m->memblock_stat = s;
  49
  50     return m;
  51 }
  52
  53 void pa_mcalign_free(pa_mcalign *m) {
  54     assert(m);
  55
  56     if (m->leftover.memblock)
  57         pa_memblock_unref(m->leftover.memblock);
  58
  59     if (m->current.memblock)
  60         pa_memblock_unref(m->current.memblock);
  61
  62     pa_xfree(m);
  63 }
  64
  65 void pa_mcalign_push(pa_mcalign *m, const pa_memchunk *c) {
  66     assert(m && c && c->memblock && c->length);
  67
  68     /* Append to the leftover memory block */
  69     if (m->leftover.memblock) {
  70         assert(!m->current.memblock);
  71
  72         /* Try to merge */
  73         if (m->leftover.memblock == c->memblock &&
  74             m->leftover.index + m->leftover.length == c->index) {
  75
  76             /* Merge */
  77             m->leftover.length += c->length;
  78
  79             /* If the new chunk is larger than m->base, move it to current */
  80             if (m->leftover.length >= m->base) {
  81                 m->current = m->leftover;
  82                 pa_memchunk_reset(&m->leftover);
  83             }
  84
  85         } else {
  86             size_t l;
  87
  88             /* We have to copy */
  89             assert(m->leftover.length < m->base);
  90             l = m->base - m->leftover.length;
  91
  92             if (l > c->length)
  93                 l = c->length;
  94
  95             /* Can we use the current block? */
  96             pa_memchunk_make_writable(&m->leftover, m->memblock_stat, m->base);
  97
  98             memcpy((uint8_t*) m->leftover.memblock->data + m->leftover.index + m->leftover.length, (uint8_t*) c->memblock->data + c->index, l);
  99             m->leftover.length += l;
 100
 101             assert(m->leftover.length <= m->base && m->leftover.length <= m->leftover.memblock->length);
 102
 103             if (c->length > l) {
 104                 /* Save the remainder of the memory block */
 105                 m->current = *c;
 106                 m->current.index += l;
 107                 m->current.length -= l;
 108                 pa_memblock_ref(m->current.memblock);
 109             }
 110         }
 111     } else {
 112         assert(!m->leftover.memblock && !m->current.memblock);
 113
 114         /* Nothing to merge or copy, just store it */
 115
 116         if (c->length >= m->base)
 117             m->current = *c;
 118         else
 119             m->leftover = *c;
 120
 121         pa_memblock_ref(c->memblock);
 122     }
 123 }
 124
 125 int pa_mcalign_pop(pa_mcalign *m, pa_memchunk *c) {
 126     assert(m && c);
 127
 128     /* First test if there's a leftover memory block available */
 129     if (m->leftover.memblock) {
 130         assert(m->leftover.length > 0 && m->leftover.length <= m->base);
 131
 132         /* The leftover memory block is not yet complete */
 133         if (m->leftover.length < m->base)
 134             return -1;
 135
 136         /* Return the leftover memory block */
 137         *c = m->leftover;
 138         pa_memchunk_reset(&m->leftover);
 139
 140         /* If the current memblock is too small move it the leftover */
 141         if (m->current.memblock && m->current.length < m->base) {
 142             m->leftover = m->current;
 143             pa_memchunk_reset(&m->current);
 144         }
 145
 146         return 0;
 147     }
 148
 149     /* Now let's see if there is other data available */
 150     if (m->current.memblock) {
 151         size_t l;
 152         assert(m->current.length >= m->base);
 153
 154         /* The length of the returned memory block */
 155         l = m->current.length;
 156         l /= m->base;
 157         l *= m->base;
 158         assert(l > 0);
 159
 160         /* Prepare the returned block */
 161         *c = m->current;
 162         pa_memblock_ref(c->memblock);
 163         c->length = l;
 164
 165         /* Drop that from the current memory block */
 166         assert(l <= m->current.length);
 167         m->current.index += l;
 168         m->current.length -= l;
 169
 170         /* In case the whole block was dropped ... */
 171         if (m->current.length == 0)
 172             pa_memblock_unref(m->current.memblock);
 173         else {
 174             /* Move the raimainder to leftover */
 175             assert(m->current.length < m->base && !m->leftover.memblock);
 176
 177             m->leftover = m->current;
 178         }
 179
 180         pa_memchunk_reset(&m->current);
 181
 182         return 0;
 183     }
 184
 185     /* There's simply nothing */
 186     return -1;
 187
 188 }