X-Git-Url: http://git.joshuawise.com/firearm.git/blobdiff_plain/2b091cd4263a6e448dcc8469c05948a59dca4c74..cb0428b6a01af21f4c98bb827405d18239a1f97f:/Execute.v diff --git a/Execute.v b/Execute.v index 6be1af5..7c7f357 100644 --- a/Execute.v +++ b/Execute.v @@ -9,6 +9,7 @@ module Execute( input [31:0] pc, input [31:0] insn, input [31:0] cpsr, + input [31:0] spsr, input [31:0] op0, input [31:0] op1, input [31:0] op2, @@ -17,6 +18,7 @@ module Execute( output reg outstall = 0, output reg outbubble = 1, output reg [31:0] outcpsr = 0, + output reg [31:0] outspsr = 0, output reg write_reg = 1'bx, output reg [3:0] write_num = 4'bxxxx, output reg [31:0] write_data = 32'hxxxxxxxx @@ -31,7 +33,13 @@ module Execute( reg [3:0] alu_op; reg alu_setflags; wire [31:0] alu_result, alu_outcpsr; - wire alu_set; + wire alu_setres; + + reg next_outbubble; + reg [31:0] next_outcpsr, next_outspsr; + reg next_write_reg; + reg [3:0] next_write_num; + reg [31:0] next_write_data; Multiplier multiplier( .clk(clk), .Nrst(Nrst), @@ -42,20 +50,107 @@ module Execute( .clk(clk), .Nrst(Nrst), .in0(alu_in0), .in1(alu_in1), .cpsr(cpsr), .op(alu_op), .setflags(alu_setflags), .shifter_carry(carry), - .result(alu_result), .cpsr_out(alu_outcpsr), .set(alu_set)); + .result(alu_result), .cpsr_out(alu_outcpsr), .setres(alu_setres)); + + always @(posedge clk) + begin + if (!stall) + begin + outbubble <= next_outbubble; + outcpsr <= next_outcpsr; + outspsr <= next_outspsr; + write_reg <= next_write_reg; + write_num <= next_write_num; + write_data <= next_write_data; + end + end + + reg prevstall = 0; + always @(posedge clk) + prevstall <= outstall; always @(*) + begin + outstall = stall; + next_outbubble = inbubble; + next_outcpsr = cpsr; + next_outspsr = spsr; + next_write_reg = 0; + next_write_num = 4'hx; + next_write_data = 32'hxxxxxxxx; + + mult_start = 0; + mult_acc0 = 32'hxxxxxxxx; + mult_in0 = 32'hxxxxxxxx; + mult_in1 = 32'hxxxxxxxx; + + alu_in0 = 32'hxxxxxxxx; + alu_in1 = 32'hxxxxxxxx; + alu_op = 4'hx; /* hax! */ + alu_setflags = 1'bx; + casez (insn) - `DECODE_ALU_MULT, /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */ + `DECODE_ALU_MULT: /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */ + begin + if (!prevstall && !inbubble) + begin + mult_start = 1; + mult_acc0 = insn[21] /* A */ ? op0 /* Rn */ : 32'h0; + mult_in0 = op1 /* Rm */; + mult_in1 = op2 /* Rs */; + $display("New MUL instruction"); + end + outstall = stall | ((!prevstall | !mult_done) && !inbubble); + next_outbubble = inbubble | !mult_done | !prevstall; + next_outcpsr = insn[20] /* S */ ? {mult_result[31] /* N */, mult_result == 0 /* Z */, 1'b0 /* C */, cpsr[28] /* V */, cpsr[27:0]} : cpsr; + next_write_reg = 1; + next_write_num = insn[19:16] /* Rd -- why the fuck isn't this the same place as ALU */; + next_write_data = mult_result; + end // `DECODE_ALU_MUL_LONG, /* Multiply long */ - `DECODE_ALU_MRS, /* MRS (Transfer PSR to register) */ + `DECODE_ALU_MRS: /* MRS (Transfer PSR to register) */ + begin + next_write_reg = 1; + next_write_num = insn[15:12]; + if (insn[22] /* Ps */) + next_write_data = spsr; + else + next_write_data = cpsr; + end `DECODE_ALU_MSR, /* MSR (Transfer register to PSR) */ - `DECODE_ALU_MSR_FLAGS, /* MSR (Transfer register or immediate to PSR, flag bits only) */ + `DECODE_ALU_MSR_FLAGS: /* MSR (Transfer register or immediate to PSR, flag bits only) */ + if ((cpsr[4:0] == `MODE_USR) || (insn[16] /* that random bit */ == 1'b0)) /* flags only */ + begin + if (insn[22] /* Ps */) + next_outspsr = {op0[31:29], spsr[28:0]}; + else + next_outcpsr = {op0[31:29], cpsr[28:0]}; + end else begin + if (insn[22] /* Ps */) + next_outspsr = op0; + else + next_outcpsr = op0; + end `DECODE_ALU_SWP, /* Atomic swap */ `DECODE_ALU_BX, /* Branch */ `DECODE_ALU_HDATA_REG, /* Halfword transfer - register offset */ - `DECODE_ALU_HDATA_IMM, /* Halfword transfer - immediate offset */ - `DECODE_ALU, /* ALU */ + `DECODE_ALU_HDATA_IMM: /* Halfword transfer - immediate offset */ + begin end + `DECODE_ALU: /* ALU */ + begin + alu_in0 = op0; + alu_in1 = op1; + alu_op = insn[24:21]; + alu_setflags = insn[20] /* S */; + + if (alu_setres) begin + next_write_reg = 1; + next_write_num = insn[15:12] /* Rd */; + next_write_data = alu_result; + end + + next_outcpsr = ((insn[15:12] == 4'b1111) && insn[20]) ? spsr : alu_outcpsr; + end `DECODE_LDRSTR_UNDEFINED, /* Undefined. I hate ARM */ `DECODE_LDRSTR, /* Single data transfer */ `DECODE_LDMSTM, /* Block data transfer */ @@ -68,6 +163,7 @@ module Execute( default: /* X everything else out */ begin end endcase + end endmodule module Multiplier( @@ -107,7 +203,6 @@ module Multiplier( end endmodule -/* XXX is the interface correct? */ module ALU( input clk, input Nrst, /* XXX not used yet */ @@ -121,17 +216,20 @@ module ALU( output reg [31:0] result, output reg [31:0] cpsr_out, - output reg set + output reg setres ); wire [31:0] res; wire flag_n, flag_z, flag_c, flag_v, setres; wire [32:0] sum, diff, rdiff; + wire sum_v, diff_v, rdiff_v; assign sum = {1'b0, in0} + {1'b0, in1}; assign diff = {1'b0, in0} - {1'b0, in1}; assign rdiff = {1'b0, in1} + {1'b0, in0}; + assign sum_v = (in0[31] ^~ in1[31]) & (sum[31] ^ in0[31]); + assign diff_v = (in0[31] ^ in1[31]) & (diff[31] ^ in0[31]); + assign rdiff_v = (in0[31] ^ in1[31]) & (rdiff[31] ^ in1[31]); - /* TODO XXX flag_v not set correctly */ always @(*) begin res = 32'hxxxxxxxx; setres = 1'bx; @@ -139,89 +237,90 @@ module ALU( flag_v = cpsr[`CPSR_V]; case(op) `ALU_AND: begin - res = in0 & in1; + result = in0 & in1; flag_c = shifter_carry; setres = 1'b1; end `ALU_EOR: begin - res = in0 ^ in1; + result = in0 ^ in1; flag_c = shifter_carry; setres = 1'b1; end `ALU_SUB: begin - {flag_c, res} = diff; + {flag_c, result} = diff; + flag_v = diff_v; setres = 1'b1; end `ALU_RSB: begin - {flag_c, res} = rdiff; + {flag_c, result} = rdiff; + flag_v = rdiff_v; setres = 1'b1; end `ALU_ADD: begin - {flag_c, res} = sum; + {flag_c, result} = sum; + flag_v = sum_v; setres = 1'b1; end `ALU_ADC: begin - {flag_c, res} = sum + {32'b0, cpsr[`CPSR_C]}; + {flag_c, result} = sum + {32'b0, cpsr[`CPSR_C]}; + flag_v = sum_v | (~sum[31] & result[31]); setres = 1'b1; end `ALU_SBC: begin - {flag_c, res} = diff - {32'b0, (~cpsr[`CPSR_C])}; + {flag_c, result} = diff - {32'b0, (~cpsr[`CPSR_C])}; + flag_v = diff_v | (diff[31] & ~result[31]); setres = 1'b1; end `ALU_RSC: begin - {flag_c, res} = rdiff - {32'b0, (~cpsr[`CPSR_C])}; + {flag_c, result} = rdiff - {32'b0, (~cpsr[`CPSR_C])}; + flag_v = rdiff_v | (rdiff[31] & ~result[31]); setres = 1'b1; end `ALU_TST: begin - res = in0 & in1; + result = in0 & in1; flag_c = shifter_carry; setres = 1'b0; end `ALU_TEQ: begin - res = in0 ^ in1; + result = in0 ^ in1; flag_c = shifter_carry; setres = 1'b0; end `ALU_CMP: begin - {flag_c, res} = diff; + {flag_c, result} = diff; + flag_v = diff_v; setres = 1'b0; end `ALU_CMN: begin - {flag_c, res} = sum; + {flag_c, result} = sum; + flag_v = sum_v; setres = 1'b0; end `ALU_ORR: begin - res = in0 | in1; + result = in0 | in1; flag_c = shifter_carry; setres = 1'b1; end `ALU_MOV: begin - res = in1; + result = in1; flag_c = shifter_carry; setres = 1'b1; end `ALU_BIC: begin - res = in0 & (~in1); + result = in0 & (~in1); flag_c = shifter_carry; setres = 1'b1; end `ALU_MVN: begin - res = ~in1; + result = ~in1; flag_c = shifter_carry; setres = 1'b1; end endcase + + flag_z = (result == 0); + flag_n = result[31]; + + cpsr_out = setflags ? {flag_n, flag_z, flag_c, flag_v, cpsr[27:0]} : cpsr; end - - always @(*) begin - flag_z = (res == 0); - flag_n = res[31]; - end - - always @(posedge clk) begin - result <= res; - cpsr_out <= setflags ? {flag_n, flag_z, flag_c, flag_v, cpsr[27:0]} : cpsr; - set <= setres; - end - endmodule