X-Git-Url: https://code.delx.au/pulseaudio/blobdiff_plain/f44ba092651aa75055e109e04b4164ea92ae7fdc..6db307360b7ef95211aff13548206464e8909882:/src/pulsecore/memblockq.c

diff --git a/src/pulsecore/memblockq.c b/src/pulsecore/memblockq.c
index ff199f1b..265da37f 100644
--- a/src/pulsecore/memblockq.c
+++ b/src/pulsecore/memblockq.c
@@ -1,18 +1,18 @@
-/* $Id$ */
-
 /***
   This file is part of PulseAudio.
- 
+
+  Copyright 2004-2006 Lennart Poettering
+
   PulseAudio is free software; you can redistribute it and/or modify
   it under the terms of the GNU Lesser General Public License as published
   by the Free Software Foundation; either version 2 of the License,
   or (at your option) any later version.
- 
+
   PulseAudio is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
   General Public License for more details.
- 
+
   You should have received a copy of the GNU Lesser General Public License
   along with PulseAudio; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
@@ -26,7 +26,6 @@
 #include <sys/time.h>
 #include <time.h>
 #include <stdio.h>
-#include <assert.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -34,24 +33,30 @@
 
 #include <pulsecore/log.h>
 #include <pulsecore/mcalign.h>
+#include <pulsecore/macro.h>
+#include <pulsecore/flist.h>
 
 #include "memblockq.h"
 
-struct memblock_list {
-    struct memblock_list *next, *prev;
+struct list_item {
+    struct list_item *next, *prev;
     int64_t index;
     pa_memchunk chunk;
 };
 
+PA_STATIC_FLIST_DECLARE(list_items, 0, pa_xfree);
+
 struct pa_memblockq {
-    struct memblock_list *blocks, *blocks_tail;
+    struct list_item *blocks, *blocks_tail;
+    struct list_item *current_read, *current_write;
     unsigned n_blocks;
-    size_t maxlength, tlength, base, prebuf, minreq;
+    size_t maxlength, tlength, base, prebuf, minreq, maxrewind;
     int64_t read_index, write_index;
-    enum { PREBUF, RUNNING } state;
-    pa_memblock_stat *memblock_stat;
-    pa_memblock *silence;
+    pa_bool_t in_prebuf;
+    pa_memchunk silence;
     pa_mcalign *mcalign;
+    int64_t missing;
+    size_t requested;
 };
 
 pa_memblockq* pa_memblockq_new(
@@ -61,125 +66,196 @@ pa_memblockq* pa_memblockq_new(
         size_t base,
         size_t prebuf,
         size_t minreq,
-        pa_memblock *silence,
-        pa_memblock_stat *s) {
-    
+        size_t maxrewind,
+        pa_memchunk *silence) {
+
     pa_memblockq* bq;
-    
-    assert(base > 0);
-    assert(maxlength >= base);
-    
+
+    pa_assert(base > 0);
+
     bq = pa_xnew(pa_memblockq, 1);
     bq->blocks = bq->blocks_tail = NULL;
+    bq->current_read = bq->current_write = NULL;
     bq->n_blocks = 0;
 
     bq->base = base;
     bq->read_index = bq->write_index = idx;
-    bq->memblock_stat = s;
 
-    pa_log_debug(__FILE__": memblockq requested: maxlength=%lu, tlength=%lu, base=%lu, prebuf=%lu, minreq=%lu",
-        (unsigned long)maxlength, (unsigned long)tlength, (unsigned long)base, (unsigned long)prebuf, (unsigned long)minreq);
+    pa_log_debug("memblockq requested: maxlength=%lu, tlength=%lu, base=%lu, prebuf=%lu, minreq=%lu maxrewind=%lu",
+                 (unsigned long) maxlength, (unsigned long) tlength, (unsigned long) base, (unsigned long) prebuf, (unsigned long) minreq, (unsigned long) maxrewind);
 
-    bq->maxlength = ((maxlength+base-1)/base)*base;
-    assert(bq->maxlength >= base);
+    bq->missing = 0;
+    bq->requested = bq->maxlength = bq->tlength = bq->prebuf = bq->minreq = bq->maxrewind = 0;
+    bq->in_prebuf = TRUE;
 
-    bq->tlength = ((tlength+base-1)/base)*base;
-    if (!bq->tlength || bq->tlength >= bq->maxlength)
-        bq->tlength = bq->maxlength;
+    pa_memblockq_set_maxlength(bq, maxlength);
+    pa_memblockq_set_tlength(bq, tlength);
+    pa_memblockq_set_prebuf(bq, prebuf);
+    pa_memblockq_set_minreq(bq, minreq);
+    pa_memblockq_set_maxrewind(bq, maxrewind);
+
+    pa_log_debug("memblockq sanitized: maxlength=%lu, tlength=%lu, base=%lu, prebuf=%lu, minreq=%lu maxrewind=%lu",
+                 (unsigned long) bq->maxlength, (unsigned long) bq->tlength, (unsigned long) bq->base, (unsigned long) bq->prebuf, (unsigned long) bq->minreq, (unsigned long) bq->maxrewind);
+
+    if (silence) {
+        bq->silence = *silence;
+        pa_memblock_ref(bq->silence.memblock);
+    } else
+        pa_memchunk_reset(&bq->silence);
+
+    bq->mcalign = pa_mcalign_new(bq->base);
 
-    bq->prebuf = (prebuf == (size_t) -1) ? bq->tlength/2 : prebuf;
-    bq->prebuf = ((bq->prebuf+base-1)/base)*base;
-    if (bq->prebuf > bq->maxlength)
-        bq->prebuf = bq->maxlength;
-
-    bq->minreq = (minreq/base)*base;
-    
-    if (bq->minreq > bq->tlength - bq->prebuf)
-        bq->minreq = bq->tlength - bq->prebuf;
-
-    if (!bq->minreq)
-        bq->minreq = 1;
-    
-    pa_log_debug(__FILE__": memblockq sanitized: maxlength=%lu, tlength=%lu, base=%lu, prebuf=%lu, minreq=%lu",
-        (unsigned long)bq->maxlength, (unsigned long)bq->tlength, (unsigned long)bq->base, (unsigned long)bq->prebuf, (unsigned long)bq->minreq);
-
-    bq->state = bq->prebuf ? PREBUF : RUNNING;
-    bq->silence = silence ? pa_memblock_ref(silence) : NULL;
-    bq->mcalign = NULL;
-    
     return bq;
 }
 
 void pa_memblockq_free(pa_memblockq* bq) {
-    assert(bq);
+    pa_assert(bq);
 
-    pa_memblockq_flush(bq);
+    pa_memblockq_silence(bq);
 
-    if (bq->silence)
-        pa_memblock_unref(bq->silence);
+    if (bq->silence.memblock)
+        pa_memblock_unref(bq->silence.memblock);
 
     if (bq->mcalign)
         pa_mcalign_free(bq->mcalign);
-    
+
     pa_xfree(bq);
 }
 
-static void drop_block(pa_memblockq *bq, struct memblock_list *q) {
-    assert(bq);
-    assert(q);
+static void fix_current_read(pa_memblockq *bq) {
+    pa_assert(bq);
+
+    if (PA_UNLIKELY(!bq->blocks)) {
+        bq->current_read = NULL;
+        return;
+    }
+
+    if (PA_UNLIKELY(!bq->current_read))
+        bq->current_read = bq->blocks;
+
+    /* Scan left */
+    while (PA_UNLIKELY(bq->current_read->index > bq->read_index))
+
+        if (bq->current_read->prev)
+            bq->current_read = bq->current_read->prev;
+        else
+            break;
+
+    /* Scan right */
+    while (PA_LIKELY(bq->current_read != NULL) && PA_UNLIKELY(bq->current_read->index + (int64_t) bq->current_read->chunk.length <= bq->read_index))
+        bq->current_read = bq->current_read->next;
+
+    /* At this point current_read will either point at or left of the
+       next block to play. It may be NULL in case everything in
+       the queue was already played */
+}
+
+static void fix_current_write(pa_memblockq *bq) {
+    pa_assert(bq);
+
+    if (PA_UNLIKELY(!bq->blocks)) {
+        bq->current_write = NULL;
+        return;
+    }
+
+    if (PA_UNLIKELY(!bq->current_write))
+        bq->current_write = bq->blocks_tail;
+
+    /* Scan right */
+    while (PA_UNLIKELY(bq->current_write->index + (int64_t) bq->current_write->chunk.length <= bq->write_index))
+
+        if (bq->current_write->next)
+            bq->current_write = bq->current_write->next;
+        else
+            break;
+
+    /* Scan left */
+    while (PA_LIKELY(bq->current_write != NULL) && PA_UNLIKELY(bq->current_write->index > bq->write_index))
+        bq->current_write = bq->current_write->prev;
+
+    /* At this point current_write will either point at or right of
+       the next block to write data to. It may be NULL in case
+       everything in the queue is still to be played */
+}
+
+static void drop_block(pa_memblockq *bq, struct list_item *q) {
+    pa_assert(bq);
+    pa_assert(q);
+
+    pa_assert(bq->n_blocks >= 1);
 
-    assert(bq->n_blocks >= 1);
-    
     if (q->prev)
         q->prev->next = q->next;
-    else
+    else {
+        pa_assert(bq->blocks == q);
         bq->blocks = q->next;
-    
+    }
+
     if (q->next)
         q->next->prev = q->prev;
-    else
+    else {
+        pa_assert(bq->blocks_tail == q);
         bq->blocks_tail = q->prev;
+    }
+
+    if (bq->current_write == q)
+        bq->current_write = q->prev;
+
+    if (bq->current_read == q)
+        bq->current_read = q->next;
 
     pa_memblock_unref(q->chunk.memblock);
-    pa_xfree(q);
+
+    if (pa_flist_push(PA_STATIC_FLIST_GET(list_items), q) < 0)
+        pa_xfree(q);
 
     bq->n_blocks--;
 }
 
-static int can_push(pa_memblockq *bq, size_t l) {
+static void drop_backlog(pa_memblockq *bq) {
+    int64_t boundary;
+    pa_assert(bq);
+
+    boundary = bq->read_index - (int64_t) bq->maxrewind;
+
+    while (bq->blocks && (bq->blocks->index + (int64_t) bq->blocks->chunk.length <= boundary))
+        drop_block(bq, bq->blocks);
+}
+
+static pa_bool_t can_push(pa_memblockq *bq, size_t l) {
     int64_t end;
 
-    assert(bq);
+    pa_assert(bq);
 
     if (bq->read_index > bq->write_index) {
-        size_t d =  bq->read_index - bq->write_index;
+        int64_t d = bq->read_index - bq->write_index;
 
-        if (l > d)
-            l -= d;
+        if ((int64_t) l > d)
+            l -= (size_t) d;
         else
-            return 1;
+            return TRUE;
     }
 
-    end = bq->blocks_tail ? bq->blocks_tail->index + bq->blocks_tail->chunk.length : 0;
+    end = bq->blocks_tail ? bq->blocks_tail->index + (int64_t) bq->blocks_tail->chunk.length : bq->write_index;
 
     /* Make sure that the list doesn't get too long */
-    if (bq->write_index + (int64_t)l > end)
-        if (bq->write_index + l - bq->read_index > bq->maxlength)
-            return 0;
+    if (bq->write_index + (int64_t) l > end)
+        if (bq->write_index + (int64_t) l - bq->read_index > (int64_t) bq->maxlength)
+            return FALSE;
 
-    return 1;
+    return TRUE;
 }
 
 int pa_memblockq_push(pa_memblockq* bq, const pa_memchunk *uchunk) {
-    
-    struct memblock_list *q, *n;
+    struct list_item *q, *n;
     pa_memchunk chunk;
-    
-    assert(bq);
-    assert(uchunk);
-    assert(uchunk->memblock);
-    assert(uchunk->length > 0);
-    assert(uchunk->index + uchunk->length <= uchunk->memblock->length);
+    int64_t old, delta;
+
+    pa_assert(bq);
+    pa_assert(uchunk);
+    pa_assert(uchunk->memblock);
+    pa_assert(uchunk->length > 0);
+    pa_assert(uchunk->index + uchunk->length <= pa_memblock_get_length(uchunk->memblock));
 
     if (uchunk->length % bq->base)
         return -1;
@@ -187,44 +263,43 @@ int pa_memblockq_push(pa_memblockq* bq, const pa_memchunk *uchunk) {
     if (!can_push(bq, uchunk->length))
         return -1;
 
+    old = bq->write_index;
     chunk = *uchunk;
-    
-    if (bq->read_index > bq->write_index) {
 
-        /* We currently have a buffer underflow, we need to drop some
-         * incoming data */
+    fix_current_write(bq);
+    q = bq->current_write;
 
-        size_t d = bq->read_index - bq->write_index;
+    /* First we advance the q pointer right of where we want to
+     * write to */
 
-        if (chunk.length > d) {
-            chunk.index += d;
-            chunk.length -= d;
-            bq->write_index = bq->read_index;
-        } else {
-            /* We drop the incoming data completely */
-            bq->write_index += chunk.length;
-            return 0;
-        }
+    if (q) {
+        while (bq->write_index + (int64_t) chunk.length > q->index)
+            if (q->next)
+                q = q->next;
+            else
+                break;
     }
-    
+
+    if (!q)
+        q = bq->blocks_tail;
+
     /* We go from back to front to look for the right place to add
      * this new entry. Drop data we will overwrite on the way */
 
-    q = bq->blocks_tail;
     while (q) {
 
-        if (bq->write_index >= q->index + (int64_t)q->chunk.length)
+        if (bq->write_index >= q->index + (int64_t) q->chunk.length)
             /* We found the entry where we need to place the new entry immediately after */
             break;
-        else if (bq->write_index + (int64_t)chunk.length <= q->index) {
+        else if (bq->write_index + (int64_t) chunk.length <= q->index) {
             /* This entry isn't touched at all, let's skip it */
             q = q->prev;
         } else if (bq->write_index <= q->index &&
-            bq->write_index + chunk.length >= q->index + q->chunk.length) {
+                   bq->write_index + (int64_t) chunk.length >= q->index + (int64_t) q->chunk.length) {
 
             /* This entry is fully replaced by the new entry, so let's drop it */
 
-            struct memblock_list *p;
+            struct list_item *p;
             p = q;
             q = q->prev;
             drop_block(bq, p);
@@ -232,23 +307,25 @@ int pa_memblockq_push(pa_memblockq* bq, const pa_memchunk *uchunk) {
             /* The write index points into this memblock, so let's
              * truncate or split it */
 
-            if (bq->write_index + chunk.length < q->index + q->chunk.length) {
+            if (bq->write_index + (int64_t) chunk.length < q->index + (int64_t) q->chunk.length) {
 
                 /* We need to save the end of this memchunk */
-                struct memblock_list *p;
+                struct list_item *p;
                 size_t d;
 
                 /* Create a new list entry for the end of thie memchunk */
-                p = pa_xnew(struct memblock_list, 1);
+                if (!(p = pa_flist_pop(PA_STATIC_FLIST_GET(list_items))))
+                    p = pa_xnew(struct list_item, 1);
+
                 p->chunk = q->chunk;
                 pa_memblock_ref(p->chunk.memblock);
 
                 /* Calculate offset */
-                d = bq->write_index + chunk.length - q->index;
-                assert(d > 0);
+                d = (size_t) (bq->write_index + (int64_t) chunk.length - q->index);
+                pa_assert(d > 0);
 
                 /* Drop it from the new entry */
-                p->index = q->index + d;
+                p->index = q->index + (int64_t) d;
                 p->chunk.length -= d;
 
                 /* Add it to the list */
@@ -263,8 +340,8 @@ int pa_memblockq_push(pa_memblockq* bq, const pa_memchunk *uchunk) {
             }
 
             /* Truncate the chunk */
-            if (!(q->chunk.length = bq->write_index - q->index)) {
-                struct memblock_list *p;
+            if (!(q->chunk.length = (size_t) (bq->write_index - q->index))) {
+                struct list_item *p;
                 p = q;
                 q = q->prev;
                 drop_block(bq, p);
@@ -275,45 +352,45 @@ int pa_memblockq_push(pa_memblockq* bq, const pa_memchunk *uchunk) {
         } else {
             size_t d;
 
-            assert(bq->write_index + (int64_t)chunk.length > q->index &&
+            pa_assert(bq->write_index + (int64_t)chunk.length > q->index &&
                    bq->write_index + (int64_t)chunk.length < q->index + (int64_t)q->chunk.length &&
                    bq->write_index < q->index);
-            
+
             /* The job overwrites the current entry at the end, so let's drop the beginning of this entry */
 
-            d = bq->write_index + chunk.length - q->index;
-            q->index += d;
+            d = (size_t) (bq->write_index + (int64_t) chunk.length - q->index);
+            q->index += (int64_t) d;
             q->chunk.index += d;
             q->chunk.length -= d;
-            
+
             q = q->prev;
         }
-        
     }
 
     if (q) {
-        assert(bq->write_index >=  q->index + (int64_t)q->chunk.length);
-        assert(!q->next || (bq->write_index + (int64_t)chunk.length <= q->next->index));
-               
+        pa_assert(bq->write_index >=  q->index + (int64_t)q->chunk.length);
+        pa_assert(!q->next || (bq->write_index + (int64_t)chunk.length <= q->next->index));
+
         /* Try to merge memory blocks */
-        
+
         if (q->chunk.memblock == chunk.memblock &&
-            q->chunk.index + (int64_t)q->chunk.length == chunk.index &&
-            bq->write_index == q->index + (int64_t)q->chunk.length) {
-            
+            q->chunk.index + q->chunk.length == chunk.index &&
+            bq->write_index == q->index + (int64_t) q->chunk.length) {
+
             q->chunk.length += chunk.length;
-            bq->write_index += chunk.length;
-            return 0;
+            bq->write_index += (int64_t) chunk.length;
+            goto finish;
         }
     } else
-        assert(!bq->blocks || (bq->write_index + (int64_t)chunk.length <= bq->blocks->index));
+        pa_assert(!bq->blocks || (bq->write_index + (int64_t)chunk.length <= bq->blocks->index));
 
+    if (!(n = pa_flist_pop(PA_STATIC_FLIST_GET(list_items))))
+        n = pa_xnew(struct list_item, 1);
 
-    n = pa_xnew(struct memblock_list, 1);
     n->chunk = chunk;
     pa_memblock_ref(n->chunk.memblock);
     n->index = bq->write_index;
-    bq->write_index += n->chunk.length;
+    bq->write_index += (int64_t) n->chunk.length;
 
     n->next = q ? q->next : bq->blocks;
     n->prev = q;
@@ -327,47 +404,95 @@ int pa_memblockq_push(pa_memblockq* bq, const pa_memchunk *uchunk) {
         n->prev->next = n;
     else
         bq->blocks = n;
-    
+
     bq->n_blocks++;
+
+finish:
+
+    delta = bq->write_index - old;
+
+    if (delta >= (int64_t) bq->requested) {
+        delta -= (int64_t) bq->requested;
+        bq->requested = 0;
+    } else {
+        bq->requested -= (size_t) delta;
+        delta = 0;
+    }
+
+    bq->missing -= delta;
+
     return 0;
 }
 
-int pa_memblockq_peek(pa_memblockq* bq, pa_memchunk *chunk) {
-    assert(bq);
-    assert(chunk);
+pa_bool_t pa_memblockq_prebuf_active(pa_memblockq *bq) {
+    pa_assert(bq);
+
+    if (bq->in_prebuf)
+        return pa_memblockq_get_length(bq) < bq->prebuf;
+    else
+        return bq->prebuf > 0 && bq->read_index >= bq->write_index;
+}
+
+static pa_bool_t update_prebuf(pa_memblockq *bq) {
+    pa_assert(bq);
 
-    if (bq->state == PREBUF) {
+    if (bq->in_prebuf) {
 
-        /* We need to pre-buffer */
         if (pa_memblockq_get_length(bq) < bq->prebuf)
-            return -1;
+            return TRUE;
 
-        bq->state = RUNNING;
+        bq->in_prebuf = FALSE;
+        return FALSE;
+    } else {
 
-    } else if (bq->prebuf > 0 && bq->read_index >= bq->write_index) {
+        if (bq->prebuf > 0 && bq->read_index >= bq->write_index) {
+            bq->in_prebuf = TRUE;
+            return TRUE;
+        }
 
-        /* Buffer underflow protection */
-        bq->state = PREBUF;
-        return -1;
+        return FALSE;
     }
-    
+}
+
+int pa_memblockq_peek(pa_memblockq* bq, pa_memchunk *chunk) {
+    int64_t d;
+    pa_assert(bq);
+    pa_assert(chunk);
+
+    /* We need to pre-buffer */
+    if (update_prebuf(bq))
+        return -1;
+
+    fix_current_read(bq);
+
     /* Do we need to spit out silence? */
-    if (!bq->blocks || bq->blocks->index > bq->read_index) {
+    if (!bq->current_read || bq->current_read->index > bq->read_index) {
 
         size_t length;
 
         /* How much silence shall we return? */
-        length = bq->blocks ? bq->blocks->index - bq->read_index : 0;
+        if (bq->current_read)
+            length = (size_t) (bq->current_read->index - bq->read_index);
+        else if (bq->write_index > bq->read_index)
+            length = (size_t) (bq->write_index - bq->read_index);
+        else
+            length = 0;
 
         /* We need to return silence, since no data is yet available */
-        if (bq->silence) {
-            chunk->memblock = pa_memblock_ref(bq->silence);
+        if (bq->silence.memblock) {
+            *chunk = bq->silence;
+            pa_memblock_ref(chunk->memblock);
+
+            if (length > 0 && length < chunk->length)
+                chunk->length = length;
 
-            if (!length || length > chunk->memblock->length)
-                length = chunk->memblock->length;
-                
-            chunk->length = length;
         } else {
+
+            /* If the memblockq is empty, return -1, otherwise return
+             * the time to sleep */
+            if (length <= 0)
+                return -1;
+
             chunk->memblock = NULL;
             chunk->length = length;
         }
@@ -377,260 +502,432 @@ int pa_memblockq_peek(pa_memblockq* bq, pa_memchunk *chunk) {
     }
 
     /* Ok, let's pass real data to the caller */
-    assert(bq->blocks->index == bq->read_index);
-    
-    *chunk = bq->blocks->chunk;
+    *chunk = bq->current_read->chunk;
     pa_memblock_ref(chunk->memblock);
 
+    pa_assert(bq->read_index >= bq->current_read->index);
+    d = bq->read_index - bq->current_read->index;
+    chunk->index += (size_t) d;
+    chunk->length -= (size_t) d;
+
     return 0;
 }
 
-void pa_memblockq_drop(pa_memblockq *bq, const pa_memchunk *chunk, size_t length) {
-    assert(bq);
-    assert(length % bq->base == 0);
-
-    assert(!chunk || length <= chunk->length);
-
-    if (chunk) {
-
-        if (bq->blocks && bq->blocks->index == bq->read_index) {
-            /* The first item in queue is valid */
-
-            /* Does the chunk match with what the user supplied us? */
-            if (memcmp(chunk, &bq->blocks->chunk, sizeof(pa_memchunk)) != 0)
-                return;
-
-        } else {
-            size_t l;
-
-            /* The first item in the queue is not yet relevant */
-
-            assert(!bq->blocks || bq->blocks->index > bq->read_index);
-            l = bq->blocks ? bq->blocks->index - bq->read_index : 0;
-
-            if (bq->silence) {
-
-                if (!l || l > bq->silence->length)
-                    l = bq->silence->length;
+void pa_memblockq_drop(pa_memblockq *bq, size_t length) {
+    int64_t old, delta;
+    pa_assert(bq);
+    pa_assert(length % bq->base == 0);
 
-            }
-
-            /* Do the entries still match? */
-            if (chunk->index != 0 || chunk->length != l || chunk->memblock != bq->silence)
-                return;
-        }
-    }
+    old = bq->read_index;
 
     while (length > 0) {
 
-        if (bq->blocks) {
-            size_t d;
+        /* Do not drop any data when we are in prebuffering mode */
+        if (update_prebuf(bq))
+            break;
 
-            assert(bq->blocks->index >= bq->read_index);
+        fix_current_read(bq);
 
-            d = (size_t) (bq->blocks->index - bq->read_index);
-            
-            if (d >= length) {
-                /* The first block is too far in the future */
-                
-                bq->read_index += length;
-                break;
-            } else {
-                
-                length -= d;
-                bq->read_index += d;
-            }
+        if (bq->current_read) {
+            int64_t p, d;
 
-            assert(bq->blocks->index == bq->read_index);
+            /* We go through this piece by piece to make sure we don't
+             * drop more than allowed by prebuf */
 
-            if (bq->blocks->chunk.length <= length) {
-                /* We need to drop the full block */
+            p = bq->current_read->index + (int64_t) bq->current_read->chunk.length;
+            pa_assert(p >= bq->read_index);
+            d = p - bq->read_index;
 
-                length -= bq->blocks->chunk.length;
-                bq->read_index += bq->blocks->chunk.length;
+            if (d > (int64_t) length)
+                d = (int64_t) length;
 
-                drop_block(bq, bq->blocks);
-            } else {
-                /* Only the start of this block needs to be dropped */
+            bq->read_index += d;
+            length -= (size_t) d;
 
-                bq->blocks->chunk.index += length;
-                bq->blocks->chunk.length -= length;
-                bq->blocks->index += length;
-                bq->read_index += length;
-                break;
-            }
-            
         } else {
 
             /* The list is empty, there's nothing we could drop */
-            bq->read_index += length;
+            bq->read_index += (int64_t) length;
             break;
         }
     }
-}
 
-int pa_memblockq_is_readable(pa_memblockq *bq) {
-    assert(bq);
+    drop_backlog(bq);
 
-    if (bq->prebuf > 0) {
-        size_t l = pa_memblockq_get_length(bq);
-        
-        if (bq->state == PREBUF && l < bq->prebuf)
-            return 0;
+    delta = bq->read_index - old;
+    bq->missing += delta;
+}
 
-        if (l <= 0)
-            return 0;
-    }
+void pa_memblockq_rewind(pa_memblockq *bq, size_t length) {
+    pa_assert(bq);
+    pa_assert(length % bq->base == 0);
+
+    /* This is kind of the inverse of pa_memblockq_drop() */
 
-    return 1;
+    bq->read_index -= (int64_t) length;
+    bq->missing -= (int64_t) length;
 }
 
-int pa_memblockq_is_writable(pa_memblockq *bq, size_t length) {
-    assert(bq);
+pa_bool_t pa_memblockq_is_readable(pa_memblockq *bq) {
+    pa_assert(bq);
 
-    if (length % bq->base)
-        return 0;
-    
-    return pa_memblockq_get_length(bq) + length <= bq->tlength;
+    if (pa_memblockq_prebuf_active(bq))
+        return FALSE;
+
+    if (pa_memblockq_get_length(bq) <= 0)
+        return FALSE;
+
+    return TRUE;
 }
 
 size_t pa_memblockq_get_length(pa_memblockq *bq) {
-    assert(bq);
+    pa_assert(bq);
 
     if (bq->write_index <= bq->read_index)
         return 0;
-    
+
     return (size_t) (bq->write_index - bq->read_index);
 }
 
 size_t pa_memblockq_missing(pa_memblockq *bq) {
     size_t l;
-    assert(bq);
+    pa_assert(bq);
 
     if ((l = pa_memblockq_get_length(bq)) >= bq->tlength)
         return 0;
 
     l = bq->tlength - l;
-    return (l >= bq->minreq) ? l : 0;
-}
-
-size_t pa_memblockq_get_minreq(pa_memblockq *bq) {
-    assert(bq);
 
-    return bq->minreq;
+    return l >= bq->minreq ? l : 0;
 }
 
 void pa_memblockq_seek(pa_memblockq *bq, int64_t offset, pa_seek_mode_t seek) {
-    assert(bq);
+    int64_t old, delta;
+    pa_assert(bq);
+
+    old = bq->write_index;
 
     switch (seek) {
         case PA_SEEK_RELATIVE:
             bq->write_index += offset;
-            return;
+            break;
         case PA_SEEK_ABSOLUTE:
             bq->write_index = offset;
-            return;
+            break;
         case PA_SEEK_RELATIVE_ON_READ:
             bq->write_index = bq->read_index + offset;
-            return;
+            break;
         case PA_SEEK_RELATIVE_END:
-            bq->write_index = (bq->blocks_tail ? bq->blocks_tail->index + (int64_t)bq->blocks_tail->chunk.length : bq->read_index) + offset;
-            return;
+            bq->write_index = (bq->blocks_tail ? bq->blocks_tail->index + (int64_t) bq->blocks_tail->chunk.length : bq->read_index) + offset;
+            break;
+        default:
+            pa_assert_not_reached();
+    }
+
+    drop_backlog(bq);
+
+    delta = bq->write_index - old;
+
+    if (delta >= (int64_t) bq->requested) {
+        delta -= (int64_t) bq->requested;
+        bq->requested = 0;
+    } else if (delta >= 0) {
+        bq->requested -= (size_t) delta;
+        delta = 0;
     }
 
-    assert(0);
+    bq->missing -= delta;
 }
 
-void pa_memblockq_flush(pa_memblockq *bq) {
-    assert(bq);
-    
-    while (bq->blocks)
-        drop_block(bq, bq->blocks);
+void pa_memblockq_flush_write(pa_memblockq *bq) {
+    int64_t old, delta;
+    pa_assert(bq);
 
-    assert(bq->n_blocks == 0);
+    pa_memblockq_silence(bq);
 
+    old = bq->write_index;
     bq->write_index = bq->read_index;
 
     pa_memblockq_prebuf_force(bq);
+
+    delta = bq->write_index - old;
+
+    if (delta >= (int64_t) bq->requested) {
+        delta -= (int64_t) bq->requested;
+        bq->requested = 0;
+    } else if (delta >= 0) {
+        bq->requested -= (size_t) delta;
+        delta = 0;
+    }
+
+    bq->missing -= delta;
+}
+
+void pa_memblockq_flush_read(pa_memblockq *bq) {
+    int64_t old, delta;
+    pa_assert(bq);
+
+    pa_memblockq_silence(bq);
+
+    old = bq->read_index;
+    bq->read_index = bq->write_index;
+
+    pa_memblockq_prebuf_force(bq);
+
+    delta = bq->read_index - old;
+    bq->missing += delta;
 }
 
 size_t pa_memblockq_get_tlength(pa_memblockq *bq) {
-    assert(bq);
-    
+    pa_assert(bq);
+
     return bq->tlength;
 }
 
+size_t pa_memblockq_get_minreq(pa_memblockq *bq) {
+    pa_assert(bq);
+
+    return bq->minreq;
+}
+
 int64_t pa_memblockq_get_read_index(pa_memblockq *bq) {
-    assert(bq);
+    pa_assert(bq);
+
     return bq->read_index;
 }
 
 int64_t pa_memblockq_get_write_index(pa_memblockq *bq) {
-    assert(bq);
+    pa_assert(bq);
+
     return bq->write_index;
 }
 
 int pa_memblockq_push_align(pa_memblockq* bq, const pa_memchunk *chunk) {
     pa_memchunk rchunk;
 
-    assert(bq);
-    assert(chunk && bq->base);
- 	
+    pa_assert(bq);
+    pa_assert(chunk);
+
     if (bq->base == 1)
         return pa_memblockq_push(bq, chunk);
- 	
-    if (!bq->mcalign)
-        bq->mcalign = pa_mcalign_new(bq->base, bq->memblock_stat);
 
     if (!can_push(bq, pa_mcalign_csize(bq->mcalign, chunk->length)))
         return -1;
-    
+
     pa_mcalign_push(bq->mcalign, chunk);
- 	
+
     while (pa_mcalign_pop(bq->mcalign, &rchunk) >= 0) {
         int r;
         r = pa_memblockq_push(bq, &rchunk);
         pa_memblock_unref(rchunk.memblock);
 
-        if (r < 0)
+        if (r < 0) {
+            pa_mcalign_flush(bq->mcalign);
             return -1;
+        }
     }
 
     return 0;
 }
 
-void pa_memblockq_shorten(pa_memblockq *bq, size_t length) {
-    size_t l;
-    assert(bq);
-
-    l = pa_memblockq_get_length(bq);
-
-    if (l > length)
-        pa_memblockq_drop(bq, NULL, l - length);
-}
-
 void pa_memblockq_prebuf_disable(pa_memblockq *bq) {
-    assert(bq);
+    pa_assert(bq);
 
-    if (bq->state == PREBUF)
-        bq->state = RUNNING;
+    bq->in_prebuf = FALSE;
 }
 
 void pa_memblockq_prebuf_force(pa_memblockq *bq) {
-    assert(bq);
+    pa_assert(bq);
 
-    if (bq->state == RUNNING && bq->prebuf > 0)
-        bq->state = PREBUF;
+    if (bq->prebuf > 0)
+        bq->in_prebuf = TRUE;
 }
 
 size_t pa_memblockq_get_maxlength(pa_memblockq *bq) {
-    assert(bq);
+    pa_assert(bq);
 
     return bq->maxlength;
 }
 
 size_t pa_memblockq_get_prebuf(pa_memblockq *bq) {
-    assert(bq);
+    pa_assert(bq);
 
     return bq->prebuf;
 }
+
+size_t pa_memblockq_pop_missing(pa_memblockq *bq) {
+    size_t l;
+
+    pa_assert(bq);
+
+/*     pa_log("pop: %lli", bq->missing); */
+
+    if (bq->missing <= 0)
+        return 0;
+
+    l = (size_t) bq->missing;
+    bq->missing = 0;
+    bq->requested += l;
+
+    return l;
+}
+
+void pa_memblockq_set_maxlength(pa_memblockq *bq, size_t maxlength) {
+    pa_assert(bq);
+
+    bq->maxlength = ((maxlength+bq->base-1)/bq->base)*bq->base;
+
+    if (bq->maxlength < bq->base)
+        bq->maxlength = bq->base;
+
+    if (bq->tlength > bq->maxlength)
+        pa_memblockq_set_tlength(bq, bq->maxlength);
+
+    if (bq->prebuf > bq->maxlength)
+        pa_memblockq_set_prebuf(bq, bq->maxlength);
+}
+
+void pa_memblockq_set_tlength(pa_memblockq *bq, size_t tlength) {
+    size_t old_tlength;
+    pa_assert(bq);
+
+    if (tlength <= 0)
+        tlength = bq->maxlength;
+
+    old_tlength = bq->tlength;
+    bq->tlength = ((tlength+bq->base-1)/bq->base)*bq->base;
+
+    if (bq->tlength > bq->maxlength)
+        bq->tlength = bq->maxlength;
+
+    if (bq->prebuf > bq->tlength)
+        pa_memblockq_set_prebuf(bq, bq->tlength);
+
+    if (bq->minreq > bq->tlength)
+        pa_memblockq_set_minreq(bq, bq->tlength);
+
+    bq->missing += (int64_t) bq->tlength - (int64_t) old_tlength;
+}
+
+void pa_memblockq_set_prebuf(pa_memblockq *bq, size_t prebuf) {
+    pa_assert(bq);
+
+    if (prebuf == (size_t) -1)
+        prebuf = bq->tlength;
+
+    bq->prebuf = ((prebuf+bq->base-1)/bq->base)*bq->base;
+
+    if (prebuf > 0 && bq->prebuf < bq->base)
+        bq->prebuf = bq->base;
+
+    if (bq->prebuf > bq->tlength)
+        bq->prebuf = bq->tlength;
+
+    if (bq->prebuf <= 0 || pa_memblockq_get_length(bq) >= bq->prebuf)
+        bq->in_prebuf = FALSE;
+
+    if (bq->minreq > bq->prebuf)
+        pa_memblockq_set_minreq(bq, bq->prebuf);
+}
+
+void pa_memblockq_set_minreq(pa_memblockq *bq, size_t minreq) {
+    pa_assert(bq);
+
+    bq->minreq = (minreq/bq->base)*bq->base;
+
+    if (bq->minreq > bq->tlength)
+        bq->minreq = bq->tlength;
+
+    if (bq->minreq > bq->prebuf)
+        bq->minreq = bq->prebuf;
+
+    if (bq->minreq < bq->base)
+        bq->minreq = bq->base;
+}
+
+void pa_memblockq_set_maxrewind(pa_memblockq *bq, size_t maxrewind) {
+    pa_assert(bq);
+
+    bq->maxrewind = (maxrewind/bq->base)*bq->base;
+}
+
+int pa_memblockq_splice(pa_memblockq *bq, pa_memblockq *source) {
+
+    pa_assert(bq);
+    pa_assert(source);
+
+    pa_memblockq_prebuf_disable(bq);
+
+    for (;;) {
+        pa_memchunk chunk;
+
+        if (pa_memblockq_peek(source, &chunk) < 0)
+            return 0;
+
+        pa_assert(chunk.length > 0);
+
+        if (chunk.memblock) {
+
+            if (pa_memblockq_push_align(bq, &chunk) < 0) {
+                pa_memblock_unref(chunk.memblock);
+                return -1;
+            }
+
+            pa_memblock_unref(chunk.memblock);
+        } else
+            pa_memblockq_seek(bq, (int64_t) chunk.length, PA_SEEK_RELATIVE);
+
+        pa_memblockq_drop(bq, chunk.length);
+    }
+}
+
+void pa_memblockq_willneed(pa_memblockq *bq) {
+    struct list_item *q;
+
+    pa_assert(bq);
+
+    fix_current_read(bq);
+
+    for (q = bq->current_read; q; q = q->next)
+        pa_memchunk_will_need(&q->chunk);
+}
+
+void pa_memblockq_set_silence(pa_memblockq *bq, pa_memchunk *silence) {
+    pa_assert(bq);
+
+    if (bq->silence.memblock)
+        pa_memblock_unref(bq->silence.memblock);
+
+    if (silence) {
+        bq->silence = *silence;
+        pa_memblock_ref(bq->silence.memblock);
+    } else
+        pa_memchunk_reset(&bq->silence);
+}
+
+pa_bool_t pa_memblockq_is_empty(pa_memblockq *bq) {
+    pa_assert(bq);
+
+    return !bq->blocks;
+}
+
+void pa_memblockq_silence(pa_memblockq *bq) {
+    pa_assert(bq);
+
+    while (bq->blocks)
+        drop_block(bq, bq->blocks);
+
+    pa_assert(bq->n_blocks == 0);
+}
+
+unsigned pa_memblockq_get_nblocks(pa_memblockq *bq) {
+    pa_assert(bq);
+
+    return bq->n_blocks;
+}
+
+size_t pa_memblockq_get_base(pa_memblockq *bq) {
+    pa_assert(bq);
+
+    return bq->base;
+}