bool LLKDUMemIn::get(int comp_idx, kdu_line_buf &line, int x_tnum)
{
int idx = comp_idx - this->first_comp_idx;
assert((idx >= 0) && (idx < num_components));
x_tnum = x_tnum*num_components+idx;
image_line_buf *scan, *prev=NULL;
for (scan = incomplete_lines; scan != NULL; prev = scan, scan = scan->next)
{
assert(scan->next_x_tnum >= x_tnum);
if (scan->next_x_tnum == x_tnum)
{
break;
}
}
if (scan == NULL)
{ // Need to read a new image line.
assert(x_tnum == 0); // Must consume in very specific order.
if (num_unread_rows == 0)
{
return false;
}
if ((scan = free_lines) == NULL)
{
scan = new image_line_buf(cols+3,num_components);
}
free_lines = scan->next;
if (prev == NULL)
{
incomplete_lines = scan;
}
else
{
prev->next = scan;
}
// Copy from image buffer into scan.
memcpy(scan->buf, mData+mCurPos, cols*num_components);
mCurPos += cols*num_components;
num_unread_rows--;
scan->accessed_samples = 0;
scan->next_x_tnum = 0;
}
assert((cols-scan->accessed_samples) >= line.get_width());
int comp_offset = idx;
kdu_byte *sp = scan->buf+num_components*scan->accessed_samples + comp_offset;
int n=line.get_width();
if (line.get_buf32() != NULL)
{
kdu_sample32 *dp = line.get_buf32();
if (line.is_absolute())
{ // 32-bit absolute integers
for (; n > 0; n--, sp+=num_components, dp++)
{
dp->ival = ((kdu_int32)(*sp)) - 128;
}
}
else
{ // true 32-bit floats
for (; n > 0; n--, sp+=num_components, dp++)
{
dp->fval = (((float)(*sp)) / 256.0F) - 0.5F;
}
}
}
else
{
kdu_sample16 *dp = line.get_buf16();
if (line.is_absolute())
{ // 16-bit absolute integers
for (; n > 0; n--, sp+=num_components, dp++)
{
dp->ival = ((kdu_int16)(*sp)) - 128;
}
}
else
{ // 16-bit normalized representation.
for (; n > 0; n--, sp+=num_components, dp++)
{
dp->ival = (((kdu_int16)(*sp)) - 128) << (KDU_FIX_POINT-8);
}
}
}
scan->next_x_tnum++;
if (idx == (num_components-1))
{
scan->accessed_samples += line.get_width();
}
if (scan->accessed_samples == cols)
{ // Send empty line to free list.
assert(scan == incomplete_lines);
incomplete_lines = scan->next;
scan->next = free_lines;
free_lines = scan;
}
return true;
}
