diff --git a/src/ieu/alu.sv b/src/ieu/alu.sv index 7979e065c..46ca2e179 100644 --- a/src/ieu/alu.sv +++ b/src/ieu/alu.sv @@ -54,7 +54,8 @@ module alu #(parameter WIDTH=32) ( logic ALUOp; // 0 for address generation addition or 1 for regular ALU ops logic Asign, Bsign; // Sign bits of A, B logic Rotate; - logic [WIDTH:0] shA; // 65 bit input source to shifter + logic [WIDTH:0] shA; // XLEN+1 bit input source to shifter + logic [WIDTH-1:0] rotA; // XLEN bit input source to shifter if (`ZBS_SUPPORTED) begin: zbsdec @@ -63,15 +64,22 @@ module alu #(parameter WIDTH=32) ( end else assign CondMaskB = B; - if (WIDTH == 64) begin - always_comb - case ({W64, SubArith}) - 2'b00: shA = {{1'b0}, A}; - 2'b01: shA = {A[63], A}; - 2'b10: shA = {{33'b0}, A[31:0]}; - 2'b11: shA = {{33{A[31]}}, A[31:0]}; - endcase - end else assign shA = (SubArith) ? {A[31], A} : {{1'b0},A}; + // Sign/Zero extend mux + if (WIDTH == 64) begin // rv64 must handle word s/z extensions + always_comb + case ({W64, SubArith}) + 2'b00: shA = {{1'b0}, A}; + 2'b01: shA = {A[63], A}; + 2'b10: shA = {{33'b0}, A[31:0]}; + 2'b11: shA = {{33{A[31]}}, A[31:0]}; + endcase + end else assign shA = (SubArith) ? {A[31], A} : {{1'b0},A}; // rv32 does need to handle s/z extensions + + // shifter rotate source select mux + if (`ZBB_SUPPORTED) begin + if (WIDTH == 64) assign rotA = (W64) ? {A[31:0], A[31:0]} : A; + else assign rotA = A; // NOTE: change this for the future! + end else assign rotA = A; if (`ZBA_SUPPORTED) begin: zbamuxes // Zero Extend Mux @@ -101,7 +109,7 @@ module alu #(parameter WIDTH=32) ( assign {Carry, Sum} = CondShiftA + CondInvB + {{(WIDTH-1){1'b0}}, SubArith}; // Shifts - shifternew sh(.shA(shA), .Amt(B[`LOG_XLEN-1:0]), .Right(Funct3[2]), .Arith(SubArith), .W64, .Y(Shift), .Rotate(Rotate)); + shifternew sh(.shA(shA), .rotA(rotA), .Amt(B[`LOG_XLEN-1:0]), .Right(Funct3[2]), .W64(W64), .Y(Shift), .Rotate(Rotate)); // Condition code flags are based on subtraction output Sum = A-B. // Overflow occurs when the numbers being subtracted have the opposite sign diff --git a/src/ieu/shifternew.sv b/src/ieu/shifternew.sv index 12f2bf999..e58a12770 100644 --- a/src/ieu/shifternew.sv +++ b/src/ieu/shifternew.sv @@ -30,120 +30,52 @@ `include "wally-config.vh" module shifternew ( - input logic [`XLEN:0] shA, // Source + input logic [`XLEN:0] shA, // shift Source + input logic [`XLEN-1:0] rotA, // rotate source input logic [`LOG_XLEN-1:0] Amt, // Shift amount - input logic Right, Arith, W64, Rotate, // Shift right, arithmetic, RV64 W-type shift + input logic Right, Rotate, W64, // Shift right, rotate signals output logic [`XLEN-1:0] Y); // Shifted result logic [2*`XLEN-2:0] z, zshift; // Input to funnel shifter, shifted amount before truncated to 32 or 64 bits - logic [`LOG_XLEN-1:0] amttrunc, offset, CondOffsetTrunc; // Shift amount adjusted for RV64, right-shift amount + logic [`LOG_XLEN-1:0] amttrunc, offset; // Shift amount adjusted for RV64, right-shift amount - if (`XLEN==32) begin:shifter // RV32 - always_comb // funnel mux - if (Right) z = {{31{shA[32]}}, shA[31:0]}; - else z = {shA[31:0], 31'b0}; - assign amttrunc = Amt; // shift amount - end else begin:shifter // RV64 - always_comb // funnel mux - if (Right) z = {{63{shA[64]}},shA[63:0]}; - else z = {shA[63:0],{63'b0}}; - assign amttrunc = W64 ? {1'b0, Amt[4:0]} : Amt; // 32- or 64-bit shift - end - // Handle left and right shifts with a funnel shifter. - // For RV32, only 32-bit shifts are needed. - // For RV64, 32- and 64-bit shifts are needed, with sign extension. - /* - // Funnel shifter input (see CMOS VLSI Design 4e Section 11.8.1, note Table 11.11 shift types wrong) - if (`XLEN==32) begin:shifter // RV32 - always_comb // funnel mux - if (Right) - if (Arith) z = {{31{A[31]}}, A}; - else z = {31'b0, A}; - else z = {A, 31'b0}; - assign amttrunc = Amt; // shift amount - end else begin:shifter // RV64 - always_comb // funnel mux - if (W64) begin // 32-bit shifts - if (Right) - if (Arith) z = {64'b0, {31{A[31]}}, A[31:0]}; - else z = {95'b0, A[31:0]}; - else z = {32'b0, A[31:0], 63'b0}; - end else begin - if (Right) - if (Arith) z = {{63{A[63]}}, A}; - else z = {63'b0, A}; - else z = {A, 63'b0}; - end - assign amttrunc = W64 ? {1'b0, Amt[4:0]} : Amt; // 32- or 64-bit shift - end - */ - /* - - if (`ZBB_SUPPORTED) begin: rotFunnel // HANDLES ROTATE + if (`ZBB_SUPPORTED) begin: rotfunnel + if (`XLEN==32) begin // rv32 with rotates + always_comb // funnel mux + case({Right, Rotate}) + 2'b00: z = {shA[31:0], 31'b0}; + 2'b01: z = {rotA,rotA[31:1]}; + 2'b10: z = {{31{shA[32]}}, shA[31:0]}; + 2'b11: z = {rotA[30:0],rotA}; + endcase + assign amttrunc = Amt; // shift amount + end else begin // rv64 with rotates + always_comb // funnel mux + case ({Right, Rotate}) + 2'b00: z = {shA[63:0],{63'b0}}; + 2'b01: z = {rotA, rotA[63:1]}; + 2'b10: z = {{63{shA[64]}},shA[63:0]}; + 2'b11: z = {rotA[62:0],rotA[63:0]}; + endcase + assign amttrunc = W64 ? {1'b0, Amt[4:0]} : Amt; // 32- or 64-bit shift + end + end else begin: norotfunnel if (`XLEN==32) begin:shifter // RV32 always_comb // funnel mux - if (Right) - if (Rotate) z = {A[30:0], A[31:0]}; //ror (rv32) - else - if (Arith) z = {{31{A[31]}}, A}; - else z = {31'b0, A}; - else - if (Rotate) z = {A[31:0], A[31:1]}; //rol (rv32) - else z = {A, 31'b0}; + if (Right) z = {{31{shA[32]}}, shA[31:0]}; + else z = {shA[31:0], 31'b0}; assign amttrunc = Amt; // shift amount end else begin:shifter // RV64 always_comb // funnel mux - if (W64) begin // 32-bit shifts - if (Right) - if (Rotate) z = {{64'b0},A[30:0],A[31:0]}; //rorw - else - if (Arith) z = {64'b0, {31{A[31]}}, A[31:0]}; - else z = {95'b0, A[31:0]}; - else - if (Rotate) z = {{64'b0},A[31:0],A[31:1]}; //rolw - else z = {32'b0, A[31:0], 63'b0}; - end else begin - if (Right) - if (Rotate) z = {A[62:0], A[63:0]}; //ror - else - if (Arith) z = {{63{A[63]}}, A}; - else z = {63'b0, A}; - else - if (Rotate) z = {A[63:0], A[63:1]}; //rol - else z = {A, 63'b0}; - end - assign amttrunc = W64 ? {1'b0, Amt[4:0]} : Amt; // 32- or 64-bit shift - end - end else begin: norotFunnel - if (`XLEN==32) begin:shifter // RV32 - always_comb // funnel mux - if (Right) - if (Arith) z = {{31{A[31]}}, A}; - else z = {31'b0, A}; - else z = {A, 31'b0}; - assign amttrunc = Amt; // shift amount - end else begin:shifter // RV64 - always_comb // funnel mux - if (W64) begin // 32-bit shifts - if (Right) - if (Arith) z = {64'b0, {31{A[31]}}, A[31:0]}; - else z = {95'b0, A[31:0]}; - else z = {32'b0, A[31:0], 63'b0}; - end else begin - if (Right) - if (Arith) z = {{63{A[63]}}, A}; - else z = {63'b0, A}; - else z = {A, 63'b0}; - end + if (Right) z = {{63{shA[64]}},shA[63:0]}; + else z = {shA[63:0],{63'b0}}; assign amttrunc = W64 ? {1'b0, Amt[4:0]} : Amt; // 32- or 64-bit shift end end - */ + // Opposite offset for right shifts assign offset = Right ? amttrunc : ~amttrunc; - //if (`XLEN == 64) assign CondOffsetTrunc = (W64 & Rotate) ? {{1'b0}, offset[4:0]} : offset; - //else assign CondOffsetTrunc = offset; // Funnel operation assign zshift = z >> offset;