src/pulsecore/mcalign.c

   1 /***
   2   This file is part of PulseAudio.
   3
   4   Copyright 2004-2006 Lennart Poettering
   5
   6   PulseAudio 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   PulseAudio 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 PulseAudio; 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 <string.h>
  29
  30 #include <pulse/xmalloc.h>
  31 #include <pulsecore/macro.h>
  32
  33 #include "mcalign.h"
  34
  35 struct pa_mcalign {
  36     size_t base;
  37     pa_memchunk leftover, current;
  38 };
  39
  40 pa_mcalign *pa_mcalign_new(size_t base) {
  41     pa_mcalign *m;
  42     pa_assert(base);
  43
  44     m = pa_xnew(pa_mcalign, 1);
  45
  46     m->base = base;
  47     pa_memchunk_reset(&m->leftover);
  48     pa_memchunk_reset(&m->current);
  49
  50     return m;
  51 }
  52
  53 void pa_mcalign_free(pa_mcalign *m) {
  54     pa_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     pa_assert(m);
  67     pa_assert(c);
  68
  69     pa_assert(c->memblock);
  70     pa_assert(c->length > 0);
  71
  72     pa_assert(!m->current.memblock);
  73
  74     /* Append to the leftover memory block */
  75     if (m->leftover.memblock) {
  76
  77         /* Try to merge */
  78         if (m->leftover.memblock == c->memblock &&
  79             m->leftover.index + m->leftover.length == c->index) {
  80
  81             /* Merge */
  82             m->leftover.length += c->length;
  83
  84             /* If the new chunk is larger than m->base, move it to current */
  85             if (m->leftover.length >= m->base) {
  86                 m->current = m->leftover;
  87                 pa_memchunk_reset(&m->leftover);
  88             }
  89
  90         } else {
  91             size_t l;
  92             void *lo_data, *m_data;
  93
  94             /* We have to copy */
  95             pa_assert(m->leftover.length < m->base);
  96             l = m->base - m->leftover.length;
  97
  98             if (l > c->length)
  99                 l = c->length;
 100
 101             /* Can we use the current block? */
 102             pa_memchunk_make_writable(&m->leftover, m->base);
 103
 104             lo_data = pa_memblock_acquire(m->leftover.memblock);
 105             m_data = pa_memblock_acquire(c->memblock);
 106             memcpy((uint8_t*) lo_data + m->leftover.index + m->leftover.length, (uint8_t*) m_data + c->index, l);
 107             pa_memblock_release(m->leftover.memblock);
 108             pa_memblock_release(c->memblock);
 109             m->leftover.length += l;
 110
 111             pa_assert(m->leftover.length <= m->base);
 112             pa_assert(m->leftover.length <= pa_memblock_get_length(m->leftover.memblock));
 113
 114             if (c->length > l) {
 115                 /* Save the remainder of the memory block */
 116                 m->current = *c;
 117                 m->current.index += l;
 118                 m->current.length -= l;
 119                 pa_memblock_ref(m->current.memblock);
 120             }
 121         }
 122     } else {
 123         /* Nothing to merge or copy, just store it */
 124
 125         if (c->length >= m->base)
 126             m->current = *c;
 127         else
 128             m->leftover = *c;
 129
 130         pa_memblock_ref(c->memblock);
 131     }
 132 }
 133
 134 int pa_mcalign_pop(pa_mcalign *m, pa_memchunk *c) {
 135     pa_assert(m);
 136     pa_assert(c);
 137
 138     /* First test if there's a leftover memory block available */
 139     if (m->leftover.memblock) {
 140         pa_assert(m->leftover.length > 0);
 141         pa_assert(m->leftover.length <= m->base);
 142
 143         /* The leftover memory block is not yet complete */
 144         if (m->leftover.length < m->base)
 145             return -1;
 146
 147         /* Return the leftover memory block */
 148         *c = m->leftover;
 149         pa_memchunk_reset(&m->leftover);
 150
 151         /* If the current memblock is too small move it the leftover */
 152         if (m->current.memblock && m->current.length < m->base) {
 153             m->leftover = m->current;
 154             pa_memchunk_reset(&m->current);
 155         }
 156
 157         return 0;
 158     }
 159
 160     /* Now let's see if there is other data available */
 161     if (m->current.memblock) {
 162         size_t l;
 163         pa_assert(m->current.length >= m->base);
 164
 165         /* The length of the returned memory block */
 166         l = m->current.length;
 167         l /= m->base;
 168         l *= m->base;
 169         pa_assert(l > 0);
 170
 171         /* Prepare the returned block */
 172         *c = m->current;
 173         pa_memblock_ref(c->memblock);
 174         c->length = l;
 175
 176         /* Drop that from the current memory block */
 177         pa_assert(l <= m->current.length);
 178         m->current.index += l;
 179         m->current.length -= l;
 180
 181         /* In case the whole block was dropped ... */
 182         if (m->current.length == 0)
 183             pa_memblock_unref(m->current.memblock);
 184         else {
 185             /* Move the raimainder to leftover */
 186             pa_assert(m->current.length < m->base && !m->leftover.memblock);
 187
 188             m->leftover = m->current;
 189         }
 190
 191         pa_memchunk_reset(&m->current);
 192
 193         return 0;
 194     }
 195
 196     /* There's simply nothing */
 197     return -1;
 198 }
 199
 200 size_t pa_mcalign_csize(pa_mcalign *m, size_t l) {
 201     pa_assert(m);
 202     pa_assert(l > 0);
 203
 204     pa_assert(!m->current.memblock);
 205
 206     if (m->leftover.memblock)
 207         l += m->leftover.length;
 208
 209     return (l/m->base)*m->base;
 210 }
 211
 212 void pa_mcalign_flush(pa_mcalign *m) {
 213     pa_memchunk chunk;
 214     pa_assert(m);
 215
 216     while (pa_mcalign_pop(m, &chunk) >= 0)
 217         pa_memblock_unref(chunk.memblock);
 218 }