FLAC__bool seek_to_absolute_sample_ogg_(FLAC__StreamDecoder *decoder, FLAC__uint64 stream_length, FLAC__uint64 target_sample)
{
	FLAC__uint64 left_pos = 0, right_pos = stream_length;
	FLAC__uint64 left_sample = 0, right_sample = FLAC__stream_decoder_get_total_samples(decoder);
	FLAC__uint64 this_frame_sample = (FLAC__uint64)0 - 1;
	FLAC__uint64 pos = 0; /* only initialized to avoid compiler warning */
	FLAC__bool did_a_seek;
	unsigned iteration = 0;

	/* In the first iterations, we will calculate the target byte position
	 * by the distance from the target sample to left_sample and
	 * right_sample (let's call it "proportional search").  After that, we
	 * will switch to binary search.
	 */
	unsigned BINARY_SEARCH_AFTER_ITERATION = 2;

	/* We will switch to a linear search once our current sample is less
	 * than this number of samples ahead of the target sample
	 */
	static const FLAC__uint64 LINEAR_SEARCH_WITHIN_SAMPLES = FLAC__MAX_BLOCK_SIZE * 2;

	/* If the total number of samples is unknown, use a large value, and
	 * force binary search immediately.
	 */
	if(right_sample == 0) {
		right_sample = (FLAC__uint64)(-1);
		BINARY_SEARCH_AFTER_ITERATION = 0;
	}

	decoder->private_->target_sample = target_sample;
	for( ; ; iteration++) {
		if (iteration == 0 || this_frame_sample > target_sample || target_sample - this_frame_sample > LINEAR_SEARCH_WITHIN_SAMPLES) {
			if (iteration >= BINARY_SEARCH_AFTER_ITERATION) {
				pos = (right_pos + left_pos) / 2;
			}
			else {
#ifndef FLAC__INTEGER_ONLY_LIBRARY
				pos = (FLAC__uint64)((FLAC__double)(target_sample - left_sample) / (FLAC__double)(right_sample - left_sample) * (FLAC__double)(right_pos - left_pos));
#else
				/* a little less accurate: */
				if ((target_sample-left_sample <= 0xffffffff) && (right_pos-left_pos <= 0xffffffff))
					pos = (FLAC__int64)(((target_sample-left_sample) * (right_pos-left_pos)) / (right_sample-left_sample));
				else /* @@@ WATCHOUT, ~2TB limit */
					pos = (FLAC__int64)((((target_sample-left_sample)>>8) * ((right_pos-left_pos)>>8)) / ((right_sample-left_sample)>>16));
#endif
				/* @@@ TODO: might want to limit pos to some distance
				 * before EOF, to make sure we land before the last frame,
				 * thereby getting a this_frame_sample and so having a better
				 * estimate.
				 */
			}

			/* physical seek */
			if(decoder->private_->seek_callback((FLAC__StreamDecoder*)decoder, (FLAC__uint64)pos, decoder->private_->client_data) != FLAC__STREAM_DECODER_SEEK_STATUS_OK) {
				decoder->protected_->state = FLAC__STREAM_DECODER_SEEK_ERROR;
				return false;
			}
			if(!FLAC__stream_decoder_flush(decoder)) {
				/* above call sets the state for us */
				return false;
			}
			did_a_seek = true;
		}
		else
			did_a_seek = false;

		decoder->private_->got_a_frame = false;
		if(!FLAC__stream_decoder_process_single(decoder)) {
			decoder->protected_->state = FLAC__STREAM_DECODER_SEEK_ERROR;
			return false;
		}
		if(!decoder->private_->got_a_frame) {
			if(did_a_seek) {
				/* this can happen if we seek to a point after the last frame; we drop
				 * to binary search right away in this case to avoid any wasted
				 * iterations of proportional search.
				 */
				right_pos = pos;
				BINARY_SEARCH_AFTER_ITERATION = 0;
			}
			else {
				/* this can probably only happen if total_samples is unknown and the
				 * target_sample is past the end of the stream
				 */
				decoder->protected_->state = FLAC__STREAM_DECODER_SEEK_ERROR;
				return false;
			}
		}
		/* our write callback will change the state when it gets to the target frame */
		else if(!decoder->private_->is_seeking) {
			break;
		}
		else {
			this_frame_sample = decoder->private_->last_frame.header.number.sample_number;
			FLAC__ASSERT(decoder->private_->last_frame.header.number_type == FLAC__FRAME_NUMBER_TYPE_SAMPLE_NUMBER);

			if (did_a_seek) {
				if (this_frame_sample <= target_sample) {
					/* The 'equal' case should not happen, since
					 * FLAC__stream_decoder_process_single()
					 * should recognize that it has hit the
					 * target sample and we would exit through
					 * the 'break' above.
					 */
					FLAC__ASSERT(this_frame_sample != target_sample);

					left_sample = this_frame_sample;
					/* sanity check to avoid infinite loop */
					if (left_pos == pos) {
						decoder->protected_->state = FLAC__STREAM_DECODER_SEEK_ERROR;
						return false;
					}
					left_pos = pos;
				}
				else if(this_frame_sample > target_sample) {
					right_sample = this_frame_sample;
					/* sanity check to avoid infinite loop */
					if (right_pos == pos) {
						decoder->protected_->state = FLAC__STREAM_DECODER_SEEK_ERROR;
						return false;
					}
					right_pos = pos;
				}
			}
		}
	}

	return true;
}
Unknown