input clk,
input Nrst, /* XXX not used yet */
- input stall,
- input flush,
+ input stall_2a,
+ input flush_2a,
- input inbubble,
- input [31:0] pc,
- input [31:0] insn,
- input [31:0] cpsr,
- input [31:0] op0,
- input [31:0] op1,
- input [31:0] op2,
- input carry,
+ input bubble_2a,
+ input [31:0] pc_2a,
+ input [31:0] insn_2a,
+ input [31:0] cpsr_2a,
+ input [31:0] spsr_2a,
+ input [31:0] op0_2a,
+ input [31:0] op1_2a,
+ input [31:0] op2_2a,
+ input carry_2a,
- output reg outstall = 0,
- output reg outbubble = 1,
- output reg [31:0] outcpsr = 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 outstall_2a = 0,
+ output reg bubble_3a = 1,
+ output reg [31:0] cpsr_3a = 0,
+ output reg [31:0] spsr_3a = 0,
+ output reg cpsrup_3a = 0,
+ output reg write_reg_3a = 1'bx,
+ output reg [3:0] write_num_3a = 4'bxxxx,
+ output reg [31:0] write_data_3a = 32'hxxxxxxxx,
+ output reg [31:0] jmppc_2a,
+ output reg jmp_2a,
+ output reg [31:0] pc_3a,
+ output reg [31:0] insn_3a,
+ output reg [31:0] op0_3a, op1_3a, op2_3a
);
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 [31:0] alu_in0_2a, alu_in1_2a;
+ reg [3:0] alu_op_2a;
+ reg alu_setflags_2a;
+ wire [31:0] alu_result_2a, alu_outcpsr_2a;
+ wire alu_setres_2a;
- reg next_outbubble;
- reg [31:0] next_outcpsr;
- reg next_write_reg;
- reg [3:0] next_write_num;
- reg [31:0] next_write_data;
+ reg next_bubble_3a;
+ reg [31:0] next_cpsr_3a, next_spsr_3a;
+ reg next_cpsrup_3a;
+ reg next_write_reg_3a;
+ reg [3:0] next_write_num_3a;
+ reg [31:0] next_write_data_3a;
+
Multiplier multiplier(
.clk(clk), .Nrst(Nrst),
.start(mult_start), .acc0(mult_acc0), .in0(mult_in0),
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));
-
+ .in0(alu_in0_2a), .in1(alu_in1_2a), .cpsr(cpsr_2a), .op(alu_op_2a),
+ .setflags(alu_setflags_2a), .shifter_carry(carry_2a),
+ .result(alu_result_2a), .cpsr_out(alu_outcpsr_2a), .setres(alu_setres_2a));
+
always @(posedge clk)
begin
- if (!stall)
+ if (!stall_2a)
begin
- outbubble <= next_outbubble;
- outcpsr <= next_outcpsr;
- write_reg <= next_write_reg;
- write_num <= next_write_num;
- write_data <= next_write_data;
+ bubble_3a <= next_bubble_3a;
+ cpsr_3a <= next_cpsr_3a;
+ spsr_3a <= next_spsr_3a;
+ cpsrup_3a <= next_cpsrup_3a;
+ write_reg_3a <= next_write_reg_3a;
+ write_num_3a <= next_write_num_3a;
+ write_data_3a <= next_write_data_3a;
+ pc_3a <= pc_2a;
+ insn_3a <= insn_2a;
+ op0_3a <= op0_2a;
+ op1_3a <= op1_2a;
+ op2_3a <= op2_2a;
end
end
-
- reg prevstall = 0;
+
+ reg delayedflush_2a = 0;
always @(posedge clk)
- prevstall <= outstall;
+ if (flush_2a && outstall_2a /* halp! I can't do it now, maybe later? */)
+ delayedflush_2a <= 1;
+ else if (!outstall_2a /* anything has been handled this time around */)
+ delayedflush_2a <= 0;
+ reg outstall_3a = 0;
+ always @(posedge clk)
+ outstall_3a <= outstall_2a;
+
+ always @(*)
+ begin
+ outstall_2a = stall_2a;
+
+ casez (insn_2a)
+ `DECODE_ALU_MULT: /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */
+ outstall_2a = outstall_2a | ((!outstall_3a | !mult_done) && !bubble_2a);
+ endcase
+ end
+
+ /* ALU inputs */
always @(*)
begin
- outstall = stall;
- next_outbubble = inbubble;
- next_outcpsr = cpsr;
- next_write_reg = 0;
- next_write_num = 4'hx;
- next_write_data = 32'hxxxxxxxx;
+ alu_in0_2a = op0_2a;
+ alu_in1_2a = op1_2a;
+ alu_op_2a = insn_2a[24:21];
+ alu_setflags_2a = insn_2a[20] /* S */;
+ end
+
+ /* Register outputs */
+ always @(*)
+ begin
+ next_cpsr_3a = cpsr_2a;
+ next_spsr_3a = spsr_2a;
+ next_cpsrup_3a = 0;
+ next_write_reg_3a = 0;
+ next_write_num_3a = 4'hx;
+ next_write_data_3a = 32'hxxxxxxxx;
+
+ casez(insn_2a)
+ `DECODE_ALU_MULT: /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */
+ begin
+ next_cpsr_3a = insn_2a[20] /* S */ ? {mult_result[31] /* N */, mult_result == 0 /* Z */, 1'b0 /* C */, cpsr_2a[28] /* V */, cpsr_2a[27:0]} : cpsr_2a;
+ next_cpsrup_3a = insn_2a[20] /* S */;
+ next_write_reg_3a = 1;
+ next_write_num_3a = insn_2a[19:16] /* Rd -- why the fuck isn't this the same place as ALU */;
+ next_write_data_3a = mult_result;
+ end
+ `DECODE_ALU_MRS: /* MRS (Transfer PSR to register) */
+ begin
+ next_write_reg_3a = 1;
+ next_write_num_3a = insn_2a[15:12];
+ if (insn_2a[22] /* Ps */)
+ next_write_data_3a = spsr_2a;
+ else
+ next_write_data_3a = cpsr_2a;
+ end
+ `DECODE_ALU_MSR, /* MSR (Transfer register to PSR) */
+ `DECODE_ALU_MSR_FLAGS: /* MSR (Transfer register or immediate to PSR, flag bits only) */
+ begin
+ if ((cpsr_2a[4:0] == `MODE_USR) || (insn_2a[16] /* that random bit */ == 1'b0)) /* flags only */
+ begin
+ if (insn_2a[22] /* Ps */)
+ next_spsr_3a = {op0_2a[31:29], spsr_2a[28:0]};
+ else
+ next_cpsr_3a = {op0_2a[31:29], cpsr_2a[28:0]};
+ end else begin
+ if (insn_2a[22] /* Ps */)
+ next_spsr_3a = op0_2a;
+ else
+ next_cpsr_3a = op0_2a;
+ end
+ next_cpsrup_3a = 1;
+ 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
+ if (alu_setres_2a) begin
+ next_write_reg_3a = 1;
+ next_write_num_3a = insn_2a[15:12] /* Rd */;
+ next_write_data_3a = alu_result_2a;
+ end
+
+ if (insn_2a[20] /* S */) begin
+ next_cpsrup_3a = 1;
+ next_cpsr_3a = ((insn_2a[15:12] == 4'b1111) && insn_2a[20]) ? spsr_2a : alu_outcpsr_2a;
+ end
+ end
+ `DECODE_LDRSTR_UNDEFINED, /* Undefined. I hate ARM */
+ `DECODE_LDRSTR, /* Single data transfer */
+ `DECODE_LDMSTM: /* Block data transfer */
+ begin end
+ `DECODE_BRANCH: /* Branch */
+ begin
+ if(insn_2a[24] /* L */) begin
+ next_write_reg_3a = 1;
+ next_write_num_3a = 4'hE; /* link register */
+ next_write_data_3a = pc_2a + 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;
-
- 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 */
+ casez(insn_2a)
+ `DECODE_ALU_MULT:
begin
- if (!prevstall && !inbubble)
+ if (!outstall_3a /* i.e., this is a new one */ && !bubble_2a /* 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 */;
+ mult_acc0 = insn_2a[21] /* A */ ? op0_2a /* Rn */ : 32'h0;
+ mult_in0 = op1_2a /* Rm */;
+ mult_in1 = op2_2a /* 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 */
+ endcase
+ end
+
+ /* Miscellaneous cleanup. */
+ always @(*)
+ begin
+ next_bubble_3a = bubble_2a | flush_2a | delayedflush_2a;
+
+ jmp_2a = 1'b0;
+ jmppc_2a = 32'h00000000;
+
+ casez (insn_2a)
+ `DECODE_ALU_MULT: /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */
+ next_bubble_3a = next_bubble_3a | !mult_done | !outstall_3a;
`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_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_ALU: /* ALU */
+ `DECODE_BRANCH:
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;
+ if(!bubble_2a && !flush_2a && !delayedflush_2a && !outstall_2a /* Let someone else take precedence. */) begin
+ jmppc_2a = pc_2a + op0_2a + 32'h8;
+ jmp_2a = 1'b1;
end
-
- next_outcpsr = alu_outcpsr;
- end
- `DECODE_LDRSTR_UNDEFINED, /* Undefined. I hate ARM */
- `DECODE_LDRSTR, /* Single data transfer */
- `DECODE_LDMSTM, /* Block data transfer */
- `DECODE_BRANCH, /* Branch */
+ end /* Branch */
`DECODE_LDCSTC, /* Coprocessor data transfer */
`DECODE_CDP, /* Coprocessor data op */
`DECODE_MRCMCR, /* Coprocessor register transfer */
end
endmodule
-/* XXX is the interface correct? */
module ALU(
input clk,
input Nrst, /* XXX not used yet */
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;
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
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
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