cvw/wally-pipelined/src/fpu/fsgn.sv
2021-07-22 12:30:46 -04:00

34 lines
990 B
Systemverilog
Executable File

//performs the fsgnj/fsgnjn/fsgnjx RISCV instructions
module fsgn (
input logic XSgnE, YSgnE,
input logic [63:0] FSrcXE,
input logic XExpMaxE,
input logic FmtE,
input logic [1:0] SgnOpCodeE,
output logic [63:0] SgnResE,
output logic SgnNVE);
logic AonesExp;
logic ResSgn;
//op code designation:
//
//00 - fsgnj - directly copy over sign value of FSrcYE
//01 - fsgnjn - negate sign value of FSrcYE
//10 - fsgnjx - XOR sign values of FSrcXE & FSrcYE
//
assign ResSgn = SgnOpCodeE[1] ? (XSgnE ^ YSgnE) : (YSgnE ^ SgnOpCodeE[0]);
assign SgnResE = FmtE ? {ResSgn, FSrcXE[62:0]} : {FSrcXE[63:32], ResSgn, FSrcXE[30:0]};
//If the exponent is all ones, then the value is either Inf or NaN,
//both of which will produce a QNaN/SNaN value of some sort. This will
//set the invalid flag high.
//the only flag that can occur during this operation is invalid
//due to changing sign on already existing NaN
assign SgnNVE = XExpMaxE & SgnResE[63];
endmodule