module Decode(
input clk,
- input [31:0] insn,
- input [31:0] inpc,
+ input stall,
+ input [31:0] insn_1a,
+ input [31:0] pc_1a,
input [31:0] incpsr,
input [31:0] inspsr,
output reg [31:0] op0,
output reg [31:0] op1,
output reg [31:0] op2,
output reg carry,
+ output reg [31:0] outcpsr,
output reg [31:0] outspsr,
- output reg [3:0] read_0,
- output reg [3:0] read_1,
- output reg [3:0] read_2,
- input [31:0] rdata_0,
- input [31:0] rdata_1,
- input [31:0] rdata_2
+ output reg [3:0] rf__read_0_1a,
+ output reg [3:0] rf__read_1_1a,
+ output reg [3:0] rf__read_2_1a,
+ input [31:0] rf__rdata_0_1a,
+ input [31:0] rf__rdata_1_1a,
+ input [31:0] rf__rdata_2_1a
);
wire [31:0] regs0, regs1, regs2;
wire shift_cflag_out;
wire [31:0] rotate_res;
- assign regs0 = (read_0 == 4'b1111) ? rpc : rdata_0;
- assign regs1 = (read_1 == 4'b1111) ? rpc : rdata_1;
- assign regs2 = rdata_2; /* use regs2 for things that cannot be r15 */
+ assign regs0 = (rf__read_0_1a == 4'b1111) ? rpc : rf__rdata_0_1a;
+ assign regs1 = (rf__read_1_1a == 4'b1111) ? rpc : rf__rdata_1_1a;
+ assign regs2 = rf__rdata_2_1a; /* use regs2 for things that cannot be r15 */
- IREALLYHATEARMSHIFT shift(.insn(insn),
+ IREALLYHATEARMSHIFT shift(.insn(insn_1a),
.operand(regs1),
.reg_amt(regs2),
.cflag_in(incpsr[`CPSR_C]),
.res(shift_res),
.cflag_out(shift_cflag_out));
- SuckLessRotator whirr(.oper({24'b0, insn[7:0]}),
- .amt(insn[11:8]),
+ SuckLessRotator whirr(.oper({24'b0, insn_1a[7:0]}),
+ .amt(insn_1a[11:8]),
.res(rotate_res));
always @(*)
- casez (insn)
+ casez (insn_1a)
`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) */
`DECODE_BRANCH, /* Branch */
`DECODE_LDCSTC, /* Coprocessor data transfer */
`DECODE_CDP, /* Coprocessor data op */
- `DECODE_MRCMCR, /* Coprocessor register transfer */
`DECODE_SWI: /* SWI */
- rpc = inpc + 8;
+ rpc = pc_1a + 8;
+ `DECODE_MRCMCR: /* Coprocessor register transfer */
+ rpc = pc_1a + 12;
`DECODE_ALU: /* ALU */
- rpc = inpc + (insn[25] ? 8 : (insn[4] ? 12 : 8));
+ rpc = pc_1a + (insn_1a[25] ? 8 : (insn_1a[4] ? 12 : 8));
default: /* X everything else out */
rpc = 32'hxxxxxxxx;
endcase
always @(*) begin
- read_0 = 4'hx;
- read_1 = 4'hx;
- read_2 = 4'hx;
+ rf__read_0_1a = 4'hx;
+ rf__read_1_1a = 4'hx;
+ rf__read_2_1a = 4'hx;
+ casez (insn_1a)
+ `DECODE_ALU_MULT: /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */
+ begin
+ rf__read_0_1a = insn_1a[15:12]; /* Rn */
+ rf__read_1_1a = insn_1a[3:0]; /* Rm */
+ rf__read_2_1a = insn_1a[11:8]; /* Rs */
+ end
+ `DECODE_ALU_MRS: /* MRS (Transfer PSR to register) */
+ begin end
+ `DECODE_ALU_MSR: /* MSR (Transfer register to PSR) */
+ rf__read_0_1a = insn_1a[3:0]; /* Rm */
+ `DECODE_ALU_MSR_FLAGS: /* MSR (Transfer register or immediate to PSR, flag bits only) */
+ rf__read_0_1a = insn_1a[3:0]; /* Rm */
+ `DECODE_ALU_SWP: /* Atomic swap */
+ begin
+ rf__read_0_1a = insn_1a[19:16]; /* Rn */
+ rf__read_1_1a = insn_1a[3:0]; /* Rm */
+ end
+ `DECODE_ALU_BX: /* Branch and exchange */
+ rf__read_0_1a = insn_1a[3:0]; /* Rn */
+ `DECODE_ALU_HDATA_REG: /* Halfword transfer - register offset */
+ begin
+ rf__read_0_1a = insn_1a[19:16];
+ rf__read_1_1a = insn_1a[3:0];
+ rf__read_2_1a = insn_1a[15:12];
+ end
+ `DECODE_ALU_HDATA_IMM: /* Halfword transfer - immediate offset */
+ begin
+ rf__read_0_1a = insn_1a[19:16];
+ rf__read_1_1a = insn_1a[15:12];
+ end
+ `DECODE_ALU: /* ALU */
+ begin
+ rf__read_0_1a = insn_1a[19:16]; /* Rn */
+ rf__read_1_1a = insn_1a[3:0]; /* Rm */
+ rf__read_2_1a = insn_1a[11:8]; /* Rs for shift */
+ end
+ `DECODE_LDRSTR_UNDEFINED: /* Undefined. I hate ARM */
+ begin end
+ `DECODE_LDRSTR: /* Single data transfer */
+ begin
+ rf__read_0_1a = insn_1a[19:16]; /* Rn */
+ rf__read_1_1a = insn_1a[3:0]; /* Rm */
+ rf__read_2_1a = insn_1a[15:12];
+ end
+ `DECODE_LDMSTM: /* Block data transfer */
+ rf__read_0_1a = insn_1a[19:16];
+ `DECODE_BRANCH: /* Branch */
+ begin end
+ `DECODE_LDCSTC: /* Coprocessor data transfer */
+ rf__read_0_1a = insn_1a[19:16];
+ `DECODE_CDP: /* Coprocessor data op */
+ begin end
+ `DECODE_MRCMCR: /* Coprocessor register transfer */
+ rf__read_0_1a = insn_1a[15:12];
+ `DECODE_SWI: /* SWI */
+ begin end
+ default:
+ $display("Undecoded instruction");
+ endcase
+ end
+
+ always @(*) begin
op0_out = 32'hxxxxxxxx;
op1_out = 32'hxxxxxxxx;
op2_out = 32'hxxxxxxxx;
carry_out = 1'bx;
- casez (insn)
+ casez (insn_1a)
`DECODE_ALU_MULT: /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */
begin
- read_0 = insn[15:12]; /* Rn */
- read_1 = insn[3:0]; /* Rm */
- read_2 = insn[11:8]; /* Rs */
-
op0_out = regs0;
op1_out = regs1;
op2_out = regs2;
end
-// `DECODE_ALU_MUL_LONG: /* Multiply long */
-// begin
-// read_0 = insn[11:8]; /* Rn */
-// read_1 = insn[3:0]; /* Rm */
-// read_2 = 4'b0; /* anyus */
-//
-// op1_res = regs1;
-// end
`DECODE_ALU_MRS: /* MRS (Transfer PSR to register) */
begin end
`DECODE_ALU_MSR: /* MSR (Transfer register to PSR) */
- begin
- read_0 = insn[3:0]; /* Rm */
-
op0_out = regs0;
- end
`DECODE_ALU_MSR_FLAGS: /* MSR (Transfer register or immediate to PSR, flag bits only) */
- begin
- read_0 = insn[3:0]; /* Rm */
-
- if(insn[25]) begin /* the constant case */
+ if(insn_1a[25]) begin /* the constant case */
op0_out = rotate_res;
end else begin
op0_out = regs0;
end
- end
`DECODE_ALU_SWP: /* Atomic swap */
begin
- read_0 = insn[19:16]; /* Rn */
- read_1 = insn[3:0]; /* Rm */
-
op0_out = regs0;
op1_out = regs1;
end
`DECODE_ALU_BX: /* Branch and exchange */
- begin
- read_0 = insn[3:0]; /* Rn */
-
op0_out = regs0;
- end
`DECODE_ALU_HDATA_REG: /* Halfword transfer - register offset */
begin
- read_0 = insn[19:16];
- read_1 = insn[3:0];
-
op0_out = regs0;
op1_out = regs1;
+ op2_out = regs2;
end
`DECODE_ALU_HDATA_IMM: /* Halfword transfer - immediate offset */
begin
- read_0 = insn[19:16];
-
op0_out = regs0;
- op1_out = {24'b0, insn[11:8], insn[3:0]};
+ op1_out = {24'b0, insn_1a[11:8], insn_1a[3:0]};
+ op2_out = regs1;
end
`DECODE_ALU: /* ALU */
begin
- read_0 = insn[19:16]; /* Rn */
- read_1 = insn[3:0]; /* Rm */
- read_2 = insn[11:8]; /* Rs for shift */
-
op0_out = regs0;
- if(insn[25]) begin /* the constant case */
+ if(insn_1a[25]) begin /* the constant case */
carry_out = incpsr[`CPSR_C];
op1_out = rotate_res;
end else begin
op1_out = shift_res;
end
end
- `DECODE_LDRSTR_UNDEFINED: /* Undefined. I hate ARM */
- begin
- /* eat shit */
- end
`DECODE_LDRSTR: /* Single data transfer */
begin
- read_0 = insn[19:16]; /* Rn */
- read_1 = insn[3:0]; /* Rm */
-
op0_out = regs0;
- if(insn[25]) begin
- op1_out = {20'b0, insn[11:0]};
+ if(!insn_1a[25] /* immediate */) begin
+ op1_out = {20'b0, insn_1a[11:0]};
carry_out = incpsr[`CPSR_C];
end else begin
op1_out = shift_res;
carry_out = shift_cflag_out;
end
+ op2_out = regs2;
end
`DECODE_LDMSTM: /* Block data transfer */
begin
- read_0 = insn[19:16];
-
op0_out = regs0;
- op1_out = {16'b0, insn[15:0]};
+ op1_out = {16'b0, insn_1a[15:0]};
end
`DECODE_BRANCH: /* Branch */
- begin
- op0_out = {{6{insn[23]}}, insn[23:0], 2'b0};
- end
+ op0_out = {{6{insn_1a[23]}}, insn_1a[23:0], 2'b0};
`DECODE_LDCSTC: /* Coprocessor data transfer */
begin
- read_0 = insn[19:16];
-
op0_out = regs0;
- op1_out = {24'b0, insn[7:0]};
+ op1_out = {24'b0, insn_1a[7:0]};
end
`DECODE_CDP: /* Coprocessor data op */
- begin
- end
+ begin end
`DECODE_MRCMCR: /* Coprocessor register transfer */
- begin
- read_0 = insn[15:12];
-
op0_out = regs0;
- end
`DECODE_SWI: /* SWI */
- begin
- end
- default:
- $display("Undecoded instruction");
+ begin end
endcase
end
-
always @ (posedge clk) begin
- op0 <= op0_out; /* Rn - always */
- op1 <= op1_out; /* 'operand 2' - Rm */
- op2 <= op2_out; /* thirdedge - Rs */
- carry <= carry_out;
- outspsr <= inspsr;
+ if (!stall)
+ begin
+ op0 <= op0_out; /* Rn - always */
+ op1 <= op1_out; /* 'operand 2' - Rm */
+ op2 <= op2_out; /* thirdedge - Rs */
+ carry <= carry_out;
+ outcpsr <= incpsr;
+ outspsr <= inspsr;
+ end
end
endmodule
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