+ let mut mask = mask;
+ let mut ima1 = IMAState::new();
+ let mut ima2 = IMAState::new();
+ for _ in 0..nblocks {
+ if (mask & 1) != 0 {
+ for i in 0..self.blk_align * 2 {
+ dst[doff + i] = 0;
+ }
+ doff += self.blk_align * 2;
+ mask >>= 1;
+ continue;
+ }
+ let pred1 = br.read_u16le()? as i16;
+ let pred2 = br.read_u16le()? as i16;
+ let step1 = br.read_byte()?;
+ let step2 = br.read_byte()?;
+ validate!((step1 as usize) < IMA_STEP_TABLE.len());
+ validate!((step2 as usize) < IMA_STEP_TABLE.len());
+ ima1.reset(pred1, step1);
+ ima2.reset(pred2, step2);
+ for _ in 0..self.blk_align {
+ let b = br.read_byte()?;
+ dst[doff] = ima1.expand_sample(b >> 4);
+ doff += 1;
+ dst[doff] = ima2.expand_sample(b & 0xF);
+ doff += 1;
+ }
+ mask >>= 1;
+ }