[otbn] Fix immediate for BN.LID/BN.SID
Immediate bits in decoder for sign-extended offset from BN.LID and
BN.SID did not match encoding in ISA. Possibly due to an earlier
encoding change that failed to update the decoder.
Signed-off-by: Greg Chadwick <gac@lowrisc.org>
diff --git a/hw/ip/otbn/rtl/otbn_decoder.sv b/hw/ip/otbn/rtl/otbn_decoder.sv
index 0b6126b..77d3ca6 100644
--- a/hw/ip/otbn/rtl/otbn_decoder.sv
+++ b/hw/ip/otbn/rtl/otbn_decoder.sv
@@ -104,7 +104,7 @@
// l type immediate is for the loop count in the LOOPI instruction and is not from the RISC-V ISA
assign imm_l_type_base = { 22'b0, insn[19:15], insn[11:7] };
// x type immediate is for BN.LID/BN.SID instructions and is not from the RISC-V ISA
- assign imm_x_type_base = { {17{insn[24]}}, insn[11:9], insn[31:25], 5'b0 };
+ assign imm_x_type_base = { {17{insn[11]}}, insn[11:9], insn[31:25], 5'b0 };
logic [WLEN-1:0] imm_i_type_bignum;
