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Add initial support for SYSTEM instructions to the decoder

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This commit is contained in:
Graham Edgecombe 2017-12-12 21:53:59 +00:00
parent 9259065656
commit d6f5bb2218
2 changed files with 46 additions and 0 deletions
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35
rv32_decode.sv
View file

@ -68,6 +68,7 @@ module rv32_decode (
logic [31:0] imm_j;
logic [31:0] shamt;
logic [31:0] zimm;
assign funct7 = instr_in[31:25];
assign rs2 = instr_in[24:20];
@ -85,6 +86,7 @@ module rv32_decode (
assign imm_j = {{12{sign}}, instr_in[19:12], instr_in[20], instr_in[30:25], instr_in[24:21], 1'b0};
assign shamt = {27'bx, rs2};
assign zimm = {27'b0, rs1};
assign rs1_unreg_out = rs1;
assign rs2_unreg_out = rs2;
@ -510,6 +512,39 @@ module rv32_decode (
/* FENCE.I */
valid_out <= 1;
end
{`RV32_OPCODE_SYSTEM, `RV32_FUNCT3_SYSTEM_PRIV, `RV32_FUNCT7_ANY}: begin
// TODO: EBREAK/ECALL
end
{`RV32_OPCODE_SYSTEM, `RV32_FUNCT3_SYSTEM_CSRRW, `RV32_FUNCT7_ANY}: begin
/* CSRRW */
valid_out <= 1;
// TODO
end
{`RV32_OPCODE_SYSTEM, `RV32_FUNCT3_SYSTEM_CSRRS, `RV32_FUNCT7_ANY}: begin
/* CSRRS */
valid_out <= 1;
// TODO
end
{`RV32_OPCODE_SYSTEM, `RV32_FUNCT3_SYSTEM_CSRRC, `RV32_FUNCT7_ANY}: begin
/* CSRRC */
valid_out <= 1;
// TODO
end
{`RV32_OPCODE_SYSTEM, `RV32_FUNCT3_SYSTEM_CSRRWI, `RV32_FUNCT7_ANY}: begin
/* CSRRWI */
valid_out <= 1;
// TODO
end
{`RV32_OPCODE_SYSTEM, `RV32_FUNCT3_SYSTEM_CSRRSI, `RV32_FUNCT7_ANY}: begin
/* CSRRSI */
valid_out <= 1;
// TODO
end
{`RV32_OPCODE_SYSTEM, `RV32_FUNCT3_SYSTEM_CSRRCI, `RV32_FUNCT7_ANY}: begin
/* CSRRCI */
valid_out <= 1;
// TODO
end
endcase
if (flush_in) begin

11
rv32_opcodes.sv
View file

@ -45,12 +45,23 @@
`define RV32_FUNCT3_MISC_MEM_FENCE 3'b000
`define RV32_FUNCT3_MISC_MEM_FENCE_I 3'b001
`define RV32_FUNCT3_SYSTEM_PRIV 3'b000
`define RV32_FUNCT3_SYSTEM_CSRRW 3'b001
`define RV32_FUNCT3_SYSTEM_CSRRS 3'b010
`define RV32_FUNCT3_SYSTEM_CSRRC 3'b011
`define RV32_FUNCT3_SYSTEM_CSRRWI 3'b101
`define RV32_FUNCT3_SYSTEM_CSRRSI 3'b110
`define RV32_FUNCT3_SYSTEM_CSRRCI 3'b111
`define RV32_FUNCT7_ANY 7'b???????
`define RV32_FUNCT7_ZERO 7'b0000000
`define RV32_FUNCT7_OP_SRA 7'b0100000
`define RV32_FUNCT7_OP_SUB 7'b0100000
`define RV32_FUNCT12_SYSTEM_PRIV_ECALL 12'b000000000000
`define RV32_FUNCT12_SYSTEM_PRIV_EBREAK 12'b000000000001
`define RV32_INSTR_NOP {12'bx, 5'b0, 3'bx, 5'b0, `RV32_OPCODE_OP_IMM}
`endif