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DecoderBuffer: add method _need()

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Move code from the FAAD decoder plugin.
This commit is contained in:
Max Kellermann 2014-07-12 01:33:12 +02:00
parent eabec967ec
commit b2b95cad20
3 changed files with 42 additions and 31 deletions
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25
src/decoder/DecoderBuffer.cxx
View File

@ -117,21 +117,40 @@ decoder_buffer_fill(DecoderBuffer *buffer)
return true;
}
static const void *
decoder_buffer_head(const DecoderBuffer *buffer)
{
return buffer->data + buffer->consumed;
}
size_t
decoder_buffer_available(const DecoderBuffer *buffer)
{
return buffer->length - buffer->consumed;;
return buffer->length - buffer->consumed;
}
ConstBuffer<void>
decoder_buffer_read(const DecoderBuffer *buffer)
{
return {
buffer->data + buffer->consumed,
buffer->length - buffer->consumed
decoder_buffer_head(buffer),
decoder_buffer_available(buffer),
};
}
ConstBuffer<void>
decoder_buffer_need(DecoderBuffer *buffer, size_t min_size)
{
while (true) {
const auto available = decoder_buffer_available(buffer);
if (available >= min_size)
return { decoder_buffer_head(buffer), available };
if (!decoder_buffer_fill(buffer))
return nullptr;
}
}
void
decoder_buffer_consume(DecoderBuffer *buffer, size_t nbytes)
{

7
src/decoder/DecoderBuffer.hxx
View File

@ -90,6 +90,13 @@ gcc_pure
ConstBuffer<void>
decoder_buffer_read(const DecoderBuffer *buffer);
/**
* Wait until this number of bytes are available. Returns nullptr on
* error.
*/
ConstBuffer<void>
decoder_buffer_need(DecoderBuffer *buffer, size_t min_size);
/**
* Consume (delete, invalidate) a part of the buffer. The "nbytes"
* parameter must not be larger than the length returned by

41
src/decoder/plugins/FaadDecoderPlugin.cxx
View File

@ -66,15 +66,10 @@ static size_t
adts_find_frame(DecoderBuffer *buffer)
{
while (true) {
auto data = ConstBuffer<uint8_t>::FromVoid(decoder_buffer_read(buffer));
if (data.size < 8) {
/* not enough data yet */
if (!decoder_buffer_fill(buffer))
/* failed */
return 0;
continue;
}
auto data = ConstBuffer<uint8_t>::FromVoid(decoder_buffer_need(buffer, 8));
if (data.IsNull())
/* failed */
return 0;
/* find the 0xff marker */
const uint8_t *p = (const uint8_t *)
@ -100,17 +95,10 @@ adts_find_frame(DecoderBuffer *buffer)
continue;
}
if (data.size < frame_length) {
/* available buffer size is smaller than the
frame will be - attempt to read more
data */
if (!decoder_buffer_fill(buffer)) {
/* not enough data; discard this frame
to prevent a possible buffer
overflow */
decoder_buffer_clear(buffer);
}
if (decoder_buffer_need(buffer, frame_length).IsNull()) {
/* not enough data; discard this frame to
prevent a possible buffer overflow */
decoder_buffer_clear(buffer);
continue;
}
@ -181,9 +169,8 @@ faad_song_duration(DecoderBuffer *buffer, InputStream &is)
const auto size = is.GetSize();
const size_t fileread = size >= 0 ? size : 0;
decoder_buffer_fill(buffer);
auto data = ConstBuffer<uint8_t>::FromVoid(decoder_buffer_read(buffer));
if (data.IsEmpty())
auto data = ConstBuffer<uint8_t>::FromVoid(decoder_buffer_need(buffer, 5));
if (data.IsNull())
return -1;
size_t tagsize = 0;
@ -195,13 +182,11 @@ faad_song_duration(DecoderBuffer *buffer, InputStream &is)
tagsize += 10;
const bool success = decoder_buffer_skip(buffer, tagsize) &&
decoder_buffer_fill(buffer);
if (!success)
if (!decoder_buffer_skip(buffer, tagsize))
return -1;
data = ConstBuffer<uint8_t>::FromVoid(decoder_buffer_read(buffer));
if (data.IsEmpty())
data = ConstBuffer<uint8_t>::FromVoid(decoder_buffer_need(buffer, 5));
if (data.IsNull())
return -1;
}