FPU Integration

[dineshannayya]

FPU Integration

[navan93]

FPU top interface

Signal	Direction	Size	Description
clk_i	Input	1	System clock
rst_ni	Input	1	Reset
operand_1	Input	32	Operand 1 for FPU operation
operand_2	Input	32	Operand 2 for FPU operation
operand_3	Input	32	Operand 3 for FPU operation
in_valid	Input	1	Indicate inputs are valid for operation
op_i	input	4	FPU operation command
out_valid_o	output	1	Indicate FPU operation complete and result is ready
result_o	output	32	FPU operation result
status_o	output	4	Status flags as per RiscV F extension FCSR

FPU operation commands:

typedef enum logic [3:0] {
    FMADD,     //(rs1 × rs2) + rs3
    FNMSUB,   //-(rs1 × rs2) + rs3
    ADD,          //rs1 + rs2
    MUL,          //rs1 x rs2 
    DIV,            //rs1 / rs2
    SQRT,       //sqrt(rs1) 
    SGNJ,      //Floating-point to floating-point sign-injection
    MINMAX, //
    CMP,       // (rs1 = rs2, rs1 < rs2, rs1 ≤ rs2)
    CLASSIFY,  // indicates the class of the floating-point numbe
    F2I,  //Float to integer
    I2F,  //Integer to float
  } operation_e;

The files ycr_pipe_idu.sv, ycr_pipe_lsu.sv, ycr_pipe_exu.sv will need modifications to decode "F" extension instructions, perform load/store from RAM to FP register file and then use FPU to perform the operation instead of the ALU.

@dineshannayya please let me know your thoughts.

[dineshannayya]

We will follow up in skype messages