Question about isa-l inflate read_in_length when state->block_state = ISAL_BLOCK_CODED.

[ZhaiMo15]

As far as I know, read_in_length > 0 only occurs when inflator reads past the eob and into the GZIP trailer, thus need to do

state->next_in -= state->read_in_length / 8;
state->avail_in += state->read_in_length / 8;
state->read_in_length = 0;
state->read_in = 0;

to make pointer correct. In this case, state->block_state is either ISAL_BLOCK_INPUT_DONE or ISAL_BLOCK_FINISH.

However, I noticed that read_in_length may greater than 0 when state->block_state = ISAL_BLOCK_CODED, I wondered why this would happen?

Moreover, let's see a example below.
I print some information before and after one isal_inflate.

Before: inputLen: 2969, avail_in: 2969, outputLen: 4096, avail_out: 4096, read_in: 0x2dc607ff, read_in_length: 32, total_out: 32768, block_state: 3
After : inputLen: 2969, avail_in: 2965, outputLen: 4096, avail_out: 0, read_in: 0x1007a044e2dc60, read_in_length: 52, total_out: 36864, block_state: 4

I have 2 questions,

1. How does this inflating only read 4 bytes(2969-2965)? Does this related to read_in_length(which is 32)?
2. If I want to recover the GZIP trailer correctly, should I use 52 or 20(52-32) as "read_in_length" in state->next_in -= state->read_in_length / 8;?

[ZhaiMo15]

Any ideas? @rhpvorderman @gbtucker