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Code Issues Releases Wiki Activity

cache: move ringbuffer read into a separate function

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No functional changes yet.
This commit is contained in:
wm4 2014-04-09 19:03:23 +02:00
parent 4c4c7bdeda
commit e7a5124b36
1 changed files with 32 additions and 17 deletions
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49
stream/cache.c
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@ -176,6 +176,35 @@ static void cache_drop_contents(struct priv *s)
s->eof = false;
}
// Copy at most dst_size from the cache at the given absolute file position pos.
// Return number of bytes that could actually be read.
// Does not advance the file position, or change anything else.
// Can be called from anywhere, as long as the mutex is held.
static size_t read_buffer(struct priv *s, unsigned char *dst,
size_t dst_size, int64_t pos)
{
if (pos >= s->max_filepos || pos < s->min_filepos)
return 0;
int64_t newb = s->max_filepos - pos; // new bytes in the buffer
pos = pos - s->offset; // file pos to buffer memory pos
if (pos < 0) {
pos += s->buffer_size;
} else if (pos >= s->buffer_size) {
pos -= s->buffer_size;
}
if (newb > s->buffer_size - pos)
newb = s->buffer_size - pos; // handle wrap...
newb = MPMIN(newb, dst_size);
assert(newb >= 0 && newb <= dst_size);
assert(pos >= 0 && pos + newb <= s->buffer_size);
memcpy(&dst[0], &s->buffer[pos], newb);
return newb;
}
// Runs in the main thread
// mutex must be held, but is sometimes temporarily dropped
static int cache_read(struct priv *s, unsigned char *buf, int size)
@ -194,23 +223,9 @@ static int cache_read(struct priv *s, unsigned char *buf, int size)
return 0;
}
int64_t newb = s->max_filepos - s->read_filepos; // new bytes in the buffer
int64_t pos = s->read_filepos - s->offset; // file pos to buffer memory pos
if (pos < 0)
pos += s->buffer_size;
else if (pos >= s->buffer_size)
pos -= s->buffer_size;
if (newb > s->buffer_size - pos)
newb = s->buffer_size - pos; // handle wrap...
newb = FFMIN(newb, size);
memcpy(buf, &s->buffer[pos], newb);
s->read_filepos += newb;
return newb;
int readb = read_buffer(s, buf, size, s->read_filepos);
s->read_filepos += readb;
return readb;
}
// Runs in the cache thread.