Error changing bit width precision for an RNN

Created by: olaiya

Hello

I'm using hls4ml of the main branch. Looking at hls4ml.version I get 0.8.0.dev11+gabaea98a

I'm looking at converting an RNN into vhdl using hls4ml. It works, but when I try and change the the bit width of the RNN precision I get errors. I have generated an example in github to demonstrate the problem.

The example can be found here:

https://github.com/olaiya/rnn_hls4ml/blob/master/rnn_hls4ml.py

If I uncomment line 106, I get errors (error snippet attached at the end).

Is this a problem, or am I setting the precision incorrectly?

You can simply run the example with

git clone https://github.com/olaiya/rnn_hls4ml.git

cd rnn_hls4ml/

python3 rnn_hls4ml.py

Thanks

Manny

In file included from firmware/parameters.h:15, from firmware/myproject.cpp:4: firmware/nnet_utils/nnet_recurrent.h: In instantiation of ‘void nnet::gru_static(bool, data_T*, res_T*, typename CONFIG_T::weight_t*, typename CONFIG_T::weight_t*, typename CONFIG_T::bias_t*, typename CONFIG_T::bias_t*) [with data_T = ap_fixed<16, 6>; res_T = ap_fixed<16, 6>; CONFIG_T = config2; typename CONFIG_T::weight_t = ap_fixed<16, 6>; typename CONFIG_T::bias_t = ap_fixed<16, 6>]’: firmware/nnet_utils/nnet_recurrent.h:539:96: required from ‘void nnet::gru_stack(hls::stream&, hls::stream&, typename CONFIG_T::weight_t*, typename CONFIG_T::weight_t*, typename CONFIG_T::bias_t*, typename CONFIG_T::bias_t*) [with data_T = nnet::array<ap_fixed<16, 6>, 1>; res_T = nnet::array<ap_fixed<16, 6>, 20>; CONFIG_T = config2; typename CONFIG_T::weight_t = ap_fixed<16, 6>; typename CONFIG_T::bias_t = ap_fixed<16, 6>]’ firmware/myproject.cpp:41:88: required from here firmware/nnet_utils/nnet_recurrent.h:440:100: error: cannot convert ‘config2::accum_t [40]’ {aka ‘ap_fixed<48, 24> [40]’} to ‘ap_fixed<16, 6>*’ 440 | typename CONFIG_T::ACT_CONFIG_GRU>::activation(inputacc_zr, tmpres_zr); | ^~~~~~~~~

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