X-Git-Url: http://git.joshuawise.com/firearm.git/blobdiff_plain/732b7730ab749590dcf0e05b3c9a0669bfd24418..33bb01526ab02a38259e52144097c930d115b456:/Execute.v?ds=sidebyside diff --git a/Execute.v b/Execute.v index ac759bb..c1049ba 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, @@ -17,9 +18,16 @@ module Execute( output reg outstall = 0, output reg outbubble = 1, output reg [31:0] outcpsr = 0, + output reg [31:0] outspsr = 0, + output reg outcpsrup = 0, output reg write_reg = 1'bx, output reg [3:0] write_num = 4'bxxxx, - output reg [31:0] write_data = 32'hxxxxxxxx + output reg [31:0] write_data = 32'hxxxxxxxx, + output reg [31:0] jmppc, + output reg jmp, + output reg [31:0] outpc, + output reg [31:0] outinsn, + output reg [31:0] outop0, outop1, outop2 ); reg mult_start; @@ -34,11 +42,13 @@ module Execute( wire alu_setres; reg next_outbubble; - reg [31:0] next_outcpsr; + reg [31:0] next_outcpsr, next_outspsr; + reg next_outcpsrup; reg next_write_reg; reg [3:0] next_write_num; + reg [31:0] next_write_data; - + Multiplier multiplier( .clk(clk), .Nrst(Nrst), .start(mult_start), .acc0(mult_acc0), .in0(mult_in0), @@ -49,39 +59,101 @@ module Execute( .in0(alu_in0), .in1(alu_in1), .cpsr(cpsr), .op(alu_op), .setflags(alu_setflags), .shifter_carry(carry), .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; + outcpsrup <= next_outcpsrup; write_reg <= next_write_reg; write_num <= next_write_num; write_data <= next_write_data; + outpc <= pc; + outinsn <= insn; + outop0 <= op0; + outop1 <= op1; + outop2 <= op2; end end + + reg delayedflush = 0; + always @(posedge clk) + if (flush && outstall /* halp! I can't do it now, maybe later? */) + delayedflush <= 1; + else if (!outstall /* anything has been handled this time around */) + delayedflush <= 0; + reg prevstall = 0; + always @(posedge clk) + prevstall <= outstall; + always @(*) begin outstall = stall; - next_outbubble = inbubble; + + casez (insn) + `DECODE_ALU_MULT: /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */ + outstall = outstall | ((!prevstall | !mult_done) && !inbubble); + endcase + end + + /* ALU inputs */ + always @(*) + begin + alu_in0 = op0; + alu_in1 = op1; + alu_op = insn[24:21]; + alu_setflags = insn[20] /* S */; + end + + /* Register outputs */ + always @(*) + begin next_outcpsr = cpsr; + next_outspsr = spsr; + next_outcpsrup = 0; next_write_reg = 0; next_write_num = 4'hx; next_write_data = 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_MUL_LONG, /* Multiply long */ - `DECODE_ALU_MRS, /* MRS (Transfer PSR to register) */ + casez(insn) + `DECODE_ALU_MULT: /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */ + begin + next_outcpsr = insn[20] /* S */ ? {mult_result[31] /* N */, mult_result == 0 /* Z */, 1'b0 /* C */, cpsr[28] /* V */, cpsr[27:0]} : cpsr; + next_outcpsrup = insn[20] /* S */; + 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_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) */ + begin + 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 + next_outcpsrup = 1; + end `DECODE_ALU_SWP, /* Atomic swap */ `DECODE_ALU_BX, /* Branch */ `DECODE_ALU_HDATA_REG, /* Halfword transfer - register offset */ @@ -89,23 +161,85 @@ module Execute( begin end `DECODE_ALU: /* ALU */ begin - alu_in0 = op0; - alu_in1 = op1; - alu_op = insn[24:21]; - alu_setflags = insn[20] /* I */; - if (alu_setres) begin next_write_reg = 1; next_write_num = insn[15:12] /* Rd */; next_write_data = alu_result; end - next_outcpsr = alu_outcpsr; + if (insn[20] /* S */) begin + next_outcpsrup = 1; + next_outcpsr = ((insn[15:12] == 4'b1111) && insn[20]) ? spsr : alu_outcpsr; + end end `DECODE_LDRSTR_UNDEFINED, /* Undefined. I hate ARM */ `DECODE_LDRSTR, /* Single data transfer */ - `DECODE_LDMSTM, /* Block data transfer */ - `DECODE_BRANCH, /* Branch */ + `DECODE_LDMSTM: /* Block data transfer */ + begin end + `DECODE_BRANCH: /* Branch */ + begin + if(insn[24] /* L */) begin + next_write_reg = 1; + next_write_num = 4'hE; /* link register */ + next_write_data = pc + 32'h4; + end + end + endcase + end + + /* Multiplier inputs */ + always @(*) + begin + mult_start = 0; + mult_acc0 = 32'hxxxxxxxx; + mult_in0 = 32'hxxxxxxxx; + mult_in1 = 32'hxxxxxxxx; + + casez(insn) + `DECODE_ALU_MULT: + begin + if (!prevstall /* i.e., this is a new one */ && !inbubble /* i.e., this is a real one */) + 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 + end + endcase + end + + /* Miscellaneous cleanup. */ + always @(*) + begin + next_outbubble = inbubble | flush | delayedflush; + + jmp = 1'b0; + jmppc = 32'h00000000; + + casez (insn) + `DECODE_ALU_MULT: /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */ + next_outbubble = next_outbubble | !mult_done | !prevstall; + `DECODE_ALU_MRS, /* MRS (Transfer PSR to register) */ + `DECODE_ALU_MSR, /* MSR (Transfer register to PSR) */ + `DECODE_ALU_MSR_FLAGS, /* MSR (Transfer register or immediate to PSR, flag bits only) */ + `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_LDRSTR_UNDEFINED, /* Undefined. I hate ARM */ + `DECODE_LDRSTR, /* Single data transfer */ + `DECODE_LDMSTM: /* Block data transfer */ + begin end + `DECODE_BRANCH: + begin + if(!inbubble && !flush && !delayedflush && !outstall /* Let someone else take precedence. */) begin + jmppc = pc + op0 + 32'h8; + jmp = 1'b1; + end + end /* Branch */ `DECODE_LDCSTC, /* Coprocessor data transfer */ `DECODE_CDP, /* Coprocessor data op */ `DECODE_MRCMCR, /* Coprocessor register transfer */ @@ -154,7 +288,6 @@ module Multiplier( end endmodule -/* XXX is the interface correct? */ module ALU( input clk, input Nrst, /* XXX not used yet */ @@ -170,15 +303,18 @@ module ALU( output reg [31:0] cpsr_out, output reg setres ); - wire [31:0] res; - wire flag_n, flag_z, flag_c, flag_v, setres; + reg [31:0] res; + reg flag_n, flag_z, flag_c, flag_v; 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 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; @@ -197,26 +333,36 @@ module ALU( end `ALU_SUB: begin {flag_c, result} = diff; + flag_c = !flag_c; + flag_v = diff_v; setres = 1'b1; end `ALU_RSB: begin {flag_c, result} = rdiff; + flag_c = !flag_c; + flag_v = rdiff_v; setres = 1'b1; end `ALU_ADD: begin {flag_c, result} = sum; + flag_v = sum_v; setres = 1'b1; end `ALU_ADC: begin {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, result} = diff - {32'b0, (~cpsr[`CPSR_C])}; + flag_c = !flag_c; + flag_v = diff_v | (diff[31] & ~result[31]); setres = 1'b1; end `ALU_RSC: begin {flag_c, result} = rdiff - {32'b0, (~cpsr[`CPSR_C])}; + flag_c = !flag_c; + flag_v = rdiff_v | (rdiff[31] & ~result[31]); setres = 1'b1; end `ALU_TST: begin @@ -231,10 +377,13 @@ module ALU( end `ALU_CMP: begin {flag_c, result} = diff; + flag_c = !flag_c; + flag_v = diff_v; setres = 1'b0; end `ALU_CMN: begin {flag_c, result} = sum; + flag_v = sum_v; setres = 1'b0; end `ALU_ORR: begin