diff options
Diffstat (limited to 'usrp2/sdr_lib/round.v')
| -rw-r--r-- | usrp2/sdr_lib/round.v | 22 |
1 files changed, 19 insertions, 3 deletions
diff --git a/usrp2/sdr_lib/round.v b/usrp2/sdr_lib/round.v index 7a137d702..5b83981c6 100644 --- a/usrp2/sdr_lib/round.v +++ b/usrp2/sdr_lib/round.v @@ -2,7 +2,7 @@ // // USRP - Universal Software Radio Peripheral // -// Copyright (C) 2007 Matt Ettus +// Copyright (C) 2011 Matt Ettus // // This program is free software; you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by @@ -24,12 +24,28 @@ module round #(parameter bits_in=0, - parameter bits_out=0) + parameter bits_out=0, + parameter round_to_zero=0, // original behavior + parameter round_to_nearest=1, // lowest noise + parameter trunc=0) // round to negative infinity (input [bits_in-1:0] in, output [bits_out-1:0] out, output [bits_in-bits_out:0] err); - assign out = in[bits_in-1:bits_in-bits_out] + (in[bits_in-1] & |in[bits_in-bits_out-1:0]); + wire round_corr; + wire round_corr_trunc = 0; + wire round_corr_rtz = (in[bits_in-1] & |in[bits_in-bits_out-1:0]); + wire round_corr_nearest = in[bits_in-bits_out-1]; + wire round_corr_nearest_safe = (~in[bits_in-1] & (&in[bits_in-2:bits_out])) ? 0 : + round_corr_nearest; + + assign round_corr = round_to_nearest ? round_corr_nearest_safe : + trunc ? round_corr_trunc : + round_to_zero ? round_corr_rtz : + 0; // default to trunc + + assign out = in[bits_in-1:bits_in-bits_out] + round_corr; + assign err = in - {out,{(bits_in-bits_out){1'b0}}}; endmodule // round |