module Decode(
input clk,
- input [31:0] insn,
- input [31:0] inpc,
- input [31:0] incpsr,
- output reg [31:0] op0,
- output reg [31:0] op1,
- output reg [31:0] op2,
- output reg carry,
+ input stall,
+ input [31:0] insn_1a,
+ input [31:0] pc_1a,
+ input [31:0] cpsr_1a,
+ input [31:0] spsr_1a,
+ output reg [31:0] op0_2a,
+ output reg [31:0] op1_2a,
+ output reg [31:0] op2_2a,
+ output reg carry_2a,
+ output reg [31:0] cpsr_2a,
+ output reg [31:0] spsr_2a,
- output [3:0] read_0,
- output [3:0] read_1,
- output [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, rpc;
- wire [31:0] op0_out, op1_out, op2_out;
- wire carry_out;
+ wire [31:0] regs0, regs1, regs2;
+ reg [31:0] rpc;
+ reg [31:0] op0_1a, op1_1a, op2_1a;
+ reg carry_1a;
/* shifter stuff */
wire [31:0] shift_oper;
wire [31:0] shift_res;
wire shift_cflag_out;
+ wire [31:0] rotate_res;
+
+ 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 */
- 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 */
+ IREALLYHATEARMSHIFT shift(.insn(insn_1a),
+ .operand(regs1),
+ .reg_amt(regs2),
+ .cflag_in(cpsr_1a[`CPSR_C]),
+ .res(shift_res),
+ .cflag_out(shift_cflag_out));
- IREALLYHATEARMSHIFT blowme(.insn(insn),
- .operand(regs1),
- .reg_amt(regs2),
- .cflag_in(incpsr[`CPSR_C]),
- .res(shift_res),
- .cflag_out(shift_cflag_out));
+ SuckLessRotator whirr(.oper({24'b0, insn_1a[7:0]}),
+ .amt(insn_1a[11:8]),
+ .res(rotate_res));
always @(*)
- casez (insn)
- 32'b????000000??????????????1001????, /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */
-// 32'b????00001???????????????1001????, /* Multiply long */
- 32'b????00010?001111????000000000000, /* MRS (Transfer PSR to register) */
- 32'b????00010?101001111100000000????, /* MSR (Transfer register to PSR) */
- 32'b????00?10?1010001111????????????, /* MSR (Transfer register or immediate to PSR, flag bits only) */
- 32'b????00010?00????????00001001????, /* Atomic swap */
- 32'b????000100101111111111110001????, /* Branch and exchange */
- 32'b????000??0??????????00001??1????, /* Halfword transfer - register offset */
- 32'b????000??1??????????00001??1????, /* Halfword transfer - register offset */
- 32'b????011????????????????????1????, /* Undefined. I hate ARM */
- 32'b????01??????????????????????????, /* Single data transfer */
- 32'b????100?????????????????????????, /* Block data transfer */
- 32'b????101?????????????????????????, /* Branch */
- 32'b????110?????????????????????????, /* Coprocessor data transfer */
- 32'b????1110???????????????????0????, /* Coprocessor data op */
- 32'b????1110???????????????????1????, /* Coprocessor register transfer */
- 32'b????1111????????????????????????: /* SWI */
- rpc = inpc - 8;
- 32'b????00??????????????????????????: /* ALU */
- rpc = inpc - (insn[25] ? 8 : (insn[4] ? 12 : 8));
- default: /* X everything else out */
+ 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_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 and exchange */
+ `DECODE_ALU_HDATA_REG, /* Halfword transfer - register offset */
+ `DECODE_ALU_HDATA_IMM, /* Halfword transfer - register offset */
+ `DECODE_LDRSTR_UNDEFINED, /* Undefined. I hate ARM */
+ `DECODE_LDRSTR, /* Single data transfer */
+ `DECODE_LDMSTM, /* Block data transfer */
+ `DECODE_BRANCH, /* Branch */
+ `DECODE_LDCSTC, /* Coprocessor data transfer */
+ `DECODE_CDP, /* Coprocessor data op */
+ `DECODE_SWI: /* SWI */
+ rpc = pc_1a + 8;
+ `DECODE_MRCMCR: /* Coprocessor register transfer */
+ rpc = pc_1a + 12;
+ `DECODE_ALU: /* ALU */
+ 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)
- 32'b????000000??????????????1001????: /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */
+ 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 */
+ 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
-// 32'b????00001???????????????1001????, /* Multiply long */
-// read_0 = insn[11:8]; /* Rn */
-// read_1 = insn[3:0]; /* Rm */
-// read_2 = 4'b0; /* anyus */
- 32'b????00010?001111????000000000000: /* MRS (Transfer PSR to register) */
+ `DECODE_ALU_MRS: /* MRS (Transfer PSR to register) */
begin end
- 32'b????00010?101001111100000000????, /* MSR (Transfer register to PSR) */
- 32'b????00?10?1010001111????????????: /* MSR (Transfer register or immediate to PSR, flag bits only) */
- read_0 = insn[3:0]; /* Rm */
- 32'b????00??????????????????????????: /* ALU */
+ `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
- read_0 = insn[19:16]; /* Rn */
- read_1 = insn[3:0]; /* Rm */
- read_2 = insn[11:8]; /* Rs for shift */
+ rf__read_0_1a = insn_1a[19:16]; /* Rn */
+ rf__read_1_1a = insn_1a[3:0]; /* Rm */
end
- 32'b????00010?00????????00001001????: /* Atomic swap */
+ `DECODE_ALU_BX: /* Branch and exchange */
+ rf__read_0_1a = insn_1a[3:0]; /* Rn */
+ `DECODE_ALU_HDATA_REG: /* Halfword transfer - register offset */
begin
- read_0 = insn[19:16]; /* Rn */
- read_1 = insn[3:0]; /* Rm */
+ 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
- 32'b????000100101111111111110001????: /* Branch and exchange */
- read_0 = insn[3:0]; /* Rn */
- 32'b????000??0??????????00001??1????: /* Halfword transfer - register offset */
+ `DECODE_ALU_HDATA_IMM: /* Halfword transfer - immediate offset */
begin
- read_0 = insn[19:16];
- read_1 = insn[3:0];
+ rf__read_0_1a = insn_1a[19:16];
+ rf__read_1_1a = insn_1a[15:12];
end
- 32'b????000??1??????????00001??1????: /* Halfword transfer - immediate offset */
+ `DECODE_ALU: /* ALU */
begin
- read_0 = insn[19:16];
+ 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
- 32'b????011????????????????????1????: /* Undefined. I hate ARM */
+ `DECODE_LDRSTR_UNDEFINED: /* Undefined. I hate ARM */
begin end
- 32'b????01??????????????????????????: /* Single data transfer */
+ `DECODE_LDRSTR: /* Single data transfer */
begin
- read_0 = insn[19:16]; /* Rn */
- read_1 = insn[3:0]; /* Rm */
+ 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
- 32'b????100?????????????????????????: /* Block data transfer */
- read_0 = insn[19:16];
- 32'b????101?????????????????????????: /* Branch */
+ `DECODE_LDMSTM: /* Block data transfer */
+ rf__read_0_1a = insn_1a[19:16];
+ `DECODE_BRANCH: /* Branch */
begin end
- 32'b????110?????????????????????????: /* Coprocessor data transfer */
- read_0 = insn[19:16];
- 32'b????1110???????????????????0????: /* Coprocessor data op */
+ `DECODE_LDCSTC: /* Coprocessor data transfer */
+ rf__read_0_1a = insn_1a[19:16];
+ `DECODE_CDP: /* Coprocessor data op */
begin end
- 32'b????1110???????????????????1????: /* Coprocessor register transfer */
- read_0 = insn[15:12];
- 32'b????1111????????????????????????: /* SWI */
+ `DECODE_MRCMCR: /* Coprocessor register transfer */
+ rf__read_0_1a = insn_1a[15:12];
+ `DECODE_SWI: /* SWI */
begin end
default:
$display("Undecoded instruction");
end
always @(*) begin
- op0_out = 32'hxxxxxxxx;
- op1_out = 32'hxxxxxxxx;
- op2_out = 32'hxxxxxxxx;
- carry_out = 1'bx;
- casez (insn)
- 32'b????000000??????????????1001????: begin /* Multiply */
- op0_out = regs0;
- op1_out = regs1;
- op2_out = regs2;
- end
-// 32'b????00001???????????????1001????: begin /* Multiply long */
-// op1_res = regs1;
-// end
- 32'b????00010?001111????000000000000: begin /* MRS (Transfer PSR to register) */
+ op0_1a = 32'hxxxxxxxx;
+ op1_1a = 32'hxxxxxxxx;
+ op2_1a = 32'hxxxxxxxx;
+ carry_1a = 1'bx;
+
+ casez (insn_1a)
+ `DECODE_ALU_MULT: /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */
+ begin
+ op0_1a = regs0;
+ op1_1a = regs1;
+ op2_1a = regs2;
end
- 32'b????00010?101001111100000000????: begin /* MSR (Transfer register to PSR) */
- op0_out = regs0;
- end
- 32'b????00?10?1010001111????????????: begin /* MSR (Transfer register or immediate to PSR, flag bits only) */
- if(insn[25]) begin /* the constant case */
- op0_out = ({24'b0, insn[7:0]} >> {insn[11:8], 1'b0}) | ({24'b0, insn[7:0]} << (5'b0 - {insn[11:8], 1'b0}));
- end else begin
- op0_out = regs0;
- end
- end
- 32'b????00??????????????????????????: begin /* ALU */
- op0_out = regs0;
- if(insn[25]) begin /* the constant case */
- carry_out = incpsr[`CPSR_C];
- op1_out = ({24'b0, insn[7:0]} >> {insn[11:8], 1'b0}) | ({24'b0, insn[7:0]} << (5'b0 - {insn[11:8], 1'b0}));
+ `DECODE_ALU_MRS: /* MRS (Transfer PSR to register) */
+ begin end
+ `DECODE_ALU_MSR: /* MSR (Transfer register to PSR) */
+ op0_1a = regs0;
+ `DECODE_ALU_MSR_FLAGS: /* MSR (Transfer register or immediate to PSR, flag bits only) */
+ if(insn_1a[25]) begin /* the constant case */
+ op0_1a = rotate_res;
end else begin
- carry_out = shift_cflag_out;
- op1_out = shift_res;
+ op0_1a = regs0;
end
+ `DECODE_ALU_SWP: /* Atomic swap */
+ begin
+ op0_1a = regs0;
+ op1_1a = regs1;
end
- 32'b????00010?00????????00001001????: begin /* Atomic swap */
- op0_out = regs0;
- op1_out = regs1;
- end
- 32'b????000100101111111111110001????: begin /* Branch and exchange */
- op0_out = regs0;
- end
- 32'b????000??0??????????00001??1????: begin /* Halfword transfer - register offset */
- op0_out = regs0;
- op1_out = regs1;
- end
- 32'b????000??1??????????00001??1????: begin /* Halfword transfer - immediate offset */
- op0_out = regs0;
- op1_out = {24'b0, insn[11:8], insn[3:0]};
+ `DECODE_ALU_BX: /* Branch and exchange */
+ op0_1a = regs0;
+ `DECODE_ALU_HDATA_REG: /* Halfword transfer - register offset */
+ begin
+ op0_1a = regs0;
+ op1_1a = regs1;
+ op2_1a = regs2;
end
- 32'b????011????????????????????1????: begin /* Undefined. I hate ARM */
- /* eat shit */
+ `DECODE_ALU_HDATA_IMM: /* Halfword transfer - immediate offset */
+ begin
+ op0_1a = regs0;
+ op1_1a = {24'b0, insn_1a[11:8], insn_1a[3:0]};
+ op2_1a = regs1;
end
- 32'b????01??????????????????????????: begin /* Single data transfer */
- op0_out = regs0;
- if(insn[25]) begin
- op1_out = {20'b0, insn[11:0]};
- carry_out = incpsr[`CPSR_C];
+ `DECODE_ALU: /* ALU */
+ begin
+ op0_1a = regs0;
+ if(insn_1a[25]) begin /* the constant case */
+ carry_1a = cpsr_1a[`CPSR_C];
+ op1_1a = rotate_res;
end else begin
- op1_out = shift_res;
- carry_out = shift_cflag_out;
+ carry_1a = shift_cflag_out;
+ op1_1a = shift_res;
end
end
- 32'b????100?????????????????????????: begin /* Block data transfer */
- op0_out = regs0;
- op1_out = {16'b0, insn[15:0]};
- end
- 32'b????101?????????????????????????: begin /* Branch */
- op0_out = {{6{insn[23]}}, insn[23:0], 2'b0};
- end
- 32'b????110?????????????????????????: begin /* Coprocessor data transfer */
- op0_out = regs0;
- op1_out = {24'b0, insn[7:0]};
- end
- 32'b????1110???????????????????0????: begin /* Coprocessor data op */
+ `DECODE_LDRSTR: /* Single data transfer */
+ begin
+ op0_1a = regs0;
+ if(!insn_1a[25] /* immediate */) begin
+ op1_1a = {20'b0, insn_1a[11:0]};
+ carry_1a = cpsr_1a[`CPSR_C];
+ end else begin
+ op1_1a = shift_res;
+ carry_1a = shift_cflag_out;
+ end
+ op2_1a = regs2;
end
- 32'b????1110???????????????????1????: begin /* Coprocessor register transfer */
- op0_out = regs0;
+ `DECODE_LDMSTM: /* Block data transfer */
+ begin
+ op0_1a = regs0;
+ op1_1a = {16'b0, insn_1a[15:0]};
end
- 32'b????1111????????????????????????: begin /* SWI */
+ `DECODE_BRANCH: /* Branch */
+ op0_1a = {{6{insn_1a[23]}}, insn_1a[23:0], 2'b0};
+ `DECODE_LDCSTC: /* Coprocessor data transfer */
+ begin
+ op0_1a = regs0;
+ op1_1a = {24'b0, insn_1a[7:0]};
end
- default: begin end
+ `DECODE_CDP: /* Coprocessor data op */
+ begin end
+ `DECODE_MRCMCR: /* Coprocessor register transfer */
+ op0_1a = regs0;
+ `DECODE_SWI: /* SWI */
+ 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;
+ if (!stall)
+ begin
+ op0_2a <= op0_1a; /* Rn - always */
+ op1_2a <= op1_1a; /* 'operand 2' - Rm */
+ op2_2a <= op2_1a; /* thirdedge - Rs */
+ carry_2a <= carry_1a;
+ cpsr_2a <= cpsr_1a;
+ spsr_2a <= spsr_1a;
+ end
end
endmodule
input [31:0] operand,
input [31:0] reg_amt,
input cflag_in,
- output [31:0] res,
- output cflag_out
+ output reg [31:0] res,
+ output reg cflag_out
);
wire [5:0] shift_amt;
- wire rshift_cout, is_arith, is_rot;
+ reg is_arith, is_rot;
+ wire rshift_cout;
wire [31:0] rshift_res;
assign shift_amt = insn[4] ? {|reg_amt[7:5], reg_amt[4:0]} /* reg-specified shift */
: {insn[11:7] == 5'b0, insn[11:7]}; /* immediate shift */
- SuckLessShifter biteme(.oper(operand),
+ SuckLessShifter barrel(.oper(operand),
.carryin(cflag_in),
.amt(shift_amt),
.is_arith(is_arith),
always @(*)
case (insn[6:5])
`SHIFT_LSL: begin
+ /* meaningless */
is_rot = 1'b0;
is_arith = 1'b0;
end
if(!insn[4] && shift_amt[4:0] == 5'b0) begin /* RRX x.x */
res = {cflag_in, operand[31:1]};
cflag_out = operand[0];
- else
+ end else begin
res = rshift_res;
cflag_out = rshift_cout;
end
input [5:0] amt,
input is_arith,
input is_rot,
- output [31:0] res,
- output carryout
+ output wire [31:0] res,
+ output wire carryout
);
wire [32:0] stage1, stage2, stage3, stage4, stage5;
- wire pushbits = is_arith & operand[31];
+ wire pushbits = is_arith & oper[31];
/* do a barrel shift */
assign stage1 = amt[5] ? {is_rot ? oper : {32{pushbits}}, oper[31]} : {oper, carryin};
- assign stage2 = amt[4] ? {is_rot ? stage1[15:0] : {16{pushbits}}, stage1[31:16], stage1[16]} : stage1;
- assign stage3 = amt[3] ? {is_rot ? stage2[7:0] : {8{pushbits}}, stage2[31:8], stage2[8]} : stage2;
- assign stage4 = amt[2] ? {is_rot ? stage3[3:0] : {4{pushbits}}, stage3[31:4], stage3[4]} : stage3;
- assign stage5 = amt[1] ? {is_rot ? stage4[1:0] : {2{pushbits}}, stage4[31:2], stage4[2]} : stage4;
- assign {res, carryout} = amt[0] ? {is_rot ? stage4[0] : pushbits, stage5[31:1], stage5[1]} : stage5;
+ assign stage2 = amt[4] ? {is_rot ? stage1[16:1] : {16{pushbits}}, stage1[32:17], stage1[16]} : stage1;
+ assign stage3 = amt[3] ? {is_rot ? stage2[8:1] : {8{pushbits}}, stage2[32:9], stage2[8]} : stage2;
+ assign stage4 = amt[2] ? {is_rot ? stage3[4:1] : {4{pushbits}}, stage3[32:5], stage3[4]} : stage3;
+ assign stage5 = amt[1] ? {is_rot ? stage4[2:1] : {2{pushbits}}, stage4[32:3], stage4[2]} : stage4;
+ assign {res, carryout} = amt[0] ? {is_rot ? stage5[1] : pushbits, stage5[32:2], stage5[1]} : stage5;
endmodule
+
+module SuckLessRotator(
+ input [31:0] oper,
+ input [3:0] amt,
+ output wire [31:0] res
+);
+
+ wire [31:0] stage1, stage2, stage3;
+ assign stage1 = amt[3] ? {oper[15:0], oper[31:16]} : oper;
+ assign stage2 = amt[2] ? {stage1[7:0], stage1[31:8]} : stage1;
+ assign stage3 = amt[1] ? {stage2[3:0], stage2[31:4]} : stage2;
+ assign res = amt[0] ? {stage3[1:0], stage3[31:2]} : stage3;
+
+endmodule
+
git.joshuawise.com / firearm.git / blobdiff