int inflate_seek(int pos, void* appdata)
// Try to go to pos. Return actual pos.
{
inflater_impl* inf = (inflater_impl*) appdata;
if (inf->m_error)
{
return inf->m_logical_stream_pos;
}
// If we're seeking backwards, then restart from the beginning.
if (pos < inf->m_logical_stream_pos)
{
inf->reset();
}
unsigned char temp[ZBUF_SIZE];
// Now seek forwards, by just reading data in blocks.
while (inf->m_logical_stream_pos < pos)
{
int to_read = pos - inf->m_logical_stream_pos;
int to_read_this_time = imin_swf(to_read, ZBUF_SIZE);
assert(to_read_this_time > 0);
int bytes_read = inf->inflate_from_stream(temp, to_read_this_time);
assert(bytes_read <= to_read_this_time);
if (bytes_read == 0)
{
// Trouble; can't seek any further.
break;
}
}
assert(inf->m_logical_stream_pos <= pos);
return inf->m_logical_stream_pos;
}
void adpcm_expand(
void* out_data_void,
stream* in,
int sample_count, // in stereo, this is number of *pairs* of samples
bool stereo)
// Utility function: uncompress ADPCM data from in stream to
// out_data[]. The output buffer must have (sample_count*2)
// bytes for mono, or (sample_count*4) bytes for stereo.
{
Sint16* out_data = (Sint16*) out_data_void;
// Read header.
int n_bits = in->read_uint(2) + 2; // 2 to 5 bits
while (sample_count)
{
// Read initial sample & index values.
int sample = in->read_sint(16);
int stepsize_index = in->read_uint(6);
assert(STEPSIZE_CT >= (1 << 6)); // ensure we don't need to clamp.
int samples_this_block = imin_swf(sample_count, 4096);
sample_count -= samples_this_block;
if (stereo == false)
{
#define DO_MONO(n) DO_MONO_BLOCK(&out_data, n, samples_this_block, in, sample, stepsize_index)
switch (n_bits)
{
default: assert(0); break;
case 2: DO_MONO(2); break;
case 3: DO_MONO(3); break;
case 4: DO_MONO(4); break;
case 5: DO_MONO(5); break;
}
}
else
{
// Stereo.
// Got values for left channel; now get initial sample
// & index for right channel.
int right_sample = in->read_sint(16);
int right_stepsize_index = in->read_uint(6);
assert(STEPSIZE_CT >= (1 << 6)); // ensure we don't need to clamp.
#define DO_STEREO(n) \
DO_STEREO_BLOCK( \
&out_data, n, samples_this_block, \
in, sample, stepsize_index, \
right_sample, right_stepsize_index)
switch (n_bits)
{
default: assert(0); break;
case 2: DO_STEREO(2); break;
case 3: DO_STEREO(3); break;
case 4: DO_STEREO(4); break;
case 5: DO_STEREO(5); break;
}
}
}
}
