github.com/olofk.serv
1
0
Fork 0
mirror of https://github.com/olofk/serv.git synced 2026-05-05 15:53:34 +00:00
Code Issues Releases Wiki Activity

Refactor and Use ALU subtractor for comparisons

Browse Source
This commit is contained in:
Olof Kindgren
2020-08-04 22:46:01 +02:00
parent 1c4e793885
commit 88a1a43438
3 changed files with 26 additions and 33 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
rtl/serv_decode.v
View File

@@ -29,7 +29,7 @@ module serv_decode
output wire o_alu_sub,
output wire [1:0] o_alu_bool_op,
output wire o_alu_cmp_eq,
output wire o_alu_cmp_uns,
output wire o_alu_cmp_sig,
output wire o_alu_sh_signed,
output wire o_alu_sh_right,
output wire [3:0] o_alu_rd_sel,
@@ -117,7 +117,10 @@ module serv_decode
(!opcode[2] & opcode[4] & opcode[0]) |
(!opcode[2] & !opcode[3] & !opcode[0])) & (|o_rf_rd_addr);
assign o_alu_sub = opcode[3] & imm30/*alu_sub_r*/;
//True for sub, sll*, b*, slt*
//False for add*, sr*
assign o_alu_sub = (!funct3[2] & (funct3[0] | (opcode[3] & imm30))) | funct3[1] | opcode[4];
/*
300 0_000 mstatus RWSC
@@ -154,7 +157,7 @@ module serv_decode
assign o_alu_cmp_eq = funct3[2:1] == 2'b00;
assign o_alu_cmp_uns = (funct3[0] & funct3[1]) | (funct3[1] & funct3[2]);
assign o_alu_cmp_sig = ~((funct3[0] & funct3[1]) | (funct3[1] & funct3[2]));
assign o_alu_sh_signed = imm30;
assign o_alu_sh_right = funct3[2];