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,
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
+ output reg [31:0] write_data = 32'hxxxxxxxx,
+ output reg [31:0] outpc,
+ output reg outflush
);
reg mult_start;
wire mult_done;
wire [31:0] mult_result;
+ reg [31:0] alu_in0, alu_in1;
+ reg [3:0] alu_op;
+ reg alu_setflags;
+ wire [31:0] alu_result, alu_outcpsr;
+ 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),
.start(mult_start), .acc0(mult_acc0), .in0(mult_in0),
.in1(mult_in1), .done(mult_done), .result(mult_result));
+
+ ALU alu(
+ .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), .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 */
+ 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) */
+ 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) */
+ 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 */
+ 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 */
+ begin end
+ `DECODE_BRANCH:
+ begin
+ outpc = pc + op0;
+ if(insn[24]) begin
+ next_write_reg = 1;
+ next_write_num = 4'hE; /* link register */
+ next_write_data = pc + 32'h4;
+ end
+ end /* Branch */
+ `DECODE_LDCSTC, /* Coprocessor data transfer */
+ `DECODE_CDP, /* Coprocessor data op */
+ `DECODE_MRCMCR, /* Coprocessor register transfer */
+ `DECODE_SWI: /* SWI */
+ begin end
+ default: /* X everything else out */
+ begin end
+ endcase
+ end
endmodule
module Multiplier(
end
end
endmodule
+
+module ALU(
+ input clk,
+ input Nrst, /* XXX not used yet */
+
+ input [31:0] in0,
+ input [31:0] in1,
+ input [31:0] cpsr,
+ input [3:0] op,
+ input setflags,
+ input shifter_carry,
+
+ output reg [31:0] result,
+ output reg [31:0] cpsr_out,
+ 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]);
+
+ always @(*) begin
+ res = 32'hxxxxxxxx;
+ setres = 1'bx;
+ flag_c = cpsr[`CPSR_C];
+ flag_v = cpsr[`CPSR_V];
+ case(op)
+ `ALU_AND: begin
+ result = in0 & in1;
+ flag_c = shifter_carry;
+ setres = 1'b1;
+ end
+ `ALU_EOR: begin
+ result = in0 ^ in1;
+ flag_c = shifter_carry;
+ setres = 1'b1;
+ end
+ `ALU_SUB: begin
+ {flag_c, result} = diff;
+ flag_v = diff_v;
+ setres = 1'b1;
+ end
+ `ALU_RSB: begin
+ {flag_c, result} = rdiff;
+ 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_v = diff_v | (diff[31] & ~result[31]);
+ setres = 1'b1;
+ end
+ `ALU_RSC: begin
+ {flag_c, result} = rdiff - {32'b0, (~cpsr[`CPSR_C])};
+ flag_v = rdiff_v | (rdiff[31] & ~result[31]);
+ setres = 1'b1;
+ end
+ `ALU_TST: begin
+ result = in0 & in1;
+ flag_c = shifter_carry;
+ setres = 1'b0;
+ end
+ `ALU_TEQ: begin
+ result = in0 ^ in1;
+ flag_c = shifter_carry;
+ setres = 1'b0;
+ end
+ `ALU_CMP: begin
+ {flag_c, result} = diff;
+ 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
+ result = in0 | in1;
+ flag_c = shifter_carry;
+ setres = 1'b1;
+ end
+ `ALU_MOV: begin
+ result = in1;
+ flag_c = shifter_carry;
+ setres = 1'b1;
+ end
+ `ALU_BIC: begin
+ result = in0 & (~in1);
+ flag_c = shifter_carry;
+ setres = 1'b1;
+ end
+ `ALU_MVN: begin
+ 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
+endmodule
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