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] jmppc,
+ output reg jmp,
output reg [31:0] outpc,
- output reg outflush
+ output reg [31:0] outinsn,
+ output reg [31:0] outop0, outop1, outop2
);
reg mult_start;
wire alu_setres;
reg next_outbubble;
- reg [31:0] next_outcpsr;
+ 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),
.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;
+ 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)
always @(*)
begin
outstall = stall;
- next_outbubble = inbubble;
+ next_outbubble = inbubble | flush | delayedflush;
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;
-
+
+ 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 */
begin
mult_in1 = op2 /* Rs */;
$display("New MUL instruction");
end
- outstall = stall | ((!prevstall | !mult_done) && !inbubble);
- next_outbubble = inbubble | !mult_done | !prevstall;
+ outstall = outstall | ((!prevstall | !mult_done) && !inbubble);
+ next_outbubble = next_outbubble | !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 */
alu_in0 = op0;
alu_in1 = op1;
alu_op = insn[24:21];
- alu_setflags = insn[20] /* I */;
+ alu_setflags = insn[20] /* S */;
if (alu_setres) begin
next_write_reg = 1;
next_write_data = alu_result;
end
- next_outcpsr = alu_outcpsr;
+ 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 */
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;
+ if(!inbubble && !flush && !delayedflush) begin
+ jmppc = pc + op0 + 32'h8;
+ if(insn[24]) begin
+ next_write_reg = 1;
+ next_write_num = 4'hE; /* link register */
+ next_write_data = pc + 32'h4;
+ end
+ jmp = 1'b1;
end
end /* Branch */
`DECODE_LDCSTC, /* Coprocessor data transfer */
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]);
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