reg [3:0] next_write_num;
reg [31:0] next_write_data;
- reg [2:0] lsr_state = 3'b001, next_lsr_state;
+ reg [3:0] lsr_state = 4'b0001, next_lsr_state;
reg [31:0] align_s1, align_s2, align_rddata;
reg [2:0] lsrh_state = 3'b001, next_lsrh_state;
reg [31:0] swp_oldval, next_swp_oldval;
reg [1:0] swp_state = 2'b01, next_swp_state;
+
+ reg do_rd_data_latch;
+ reg [31:0] rd_data_latch = 32'hxxxxxxxx;
always @(posedge clk)
begin
lsm_state <= next_lsm_state;
lsr_state <= next_lsr_state;
lsrh_state <= next_lsrh_state;
+ if (do_rd_data_latch)
+ rd_data_latch <= rd_data;
prevaddr <= addr;
end
busaddr = 32'hxxxxxxxx;
data_size = 3'bxxx;
outstall = 1'b0;
+ st_read = 4'hx;
+ do_rd_data_latch = 0;
next_write_reg = write_reg;
next_write_num = write_num;
next_write_data = write_data;
next_swp_state = swp_state;
cur_reg = prev_reg;
+`define SWP_READING 2'b01
+`define SWP_WRITING 2'b10
+
+`define LSRH_MEMIO 3'b001
+`define LSRH_BASEWB 3'b010
+`define LSRH_WBFLUSH 3'b100
+
+`define LSR_MEMIO 4'b0001
+`define LSR_STRB_WR 4'b0010
+`define LSR_BASEWB 4'b0100
+`define LSR_WBFLUSH 4'b1000
+
+`define LSM_SETUP 4'b0001
+`define LSM_MEMIO 4'b0010
+`define LSM_BASEWB 4'b0100
+`define LSM_WBFLUSH 4'b1000
+
/* XXX shit not given about endianness */
casez(insn)
`DECODE_ALU_SWP: if(!inbubble) begin
busaddr = {op0[31:2], 2'b0};
data_size = insn[22] ? 3'b001 : 3'b100;
case(swp_state)
- 2'b01: begin
+ `SWP_READING: begin
rd_req = 1'b1;
outstall = 1'b1;
if(!rw_wait) begin
- next_swp_state = 2'b10;
+ next_swp_state = `SWP_WRITING;
next_swp_oldval = rd_data;
end
$display("SWP: read stage");
end
- 2'b10: begin
+ `SWP_WRITING: begin
wr_req = 1'b1;
wr_data = insn[22] ? {4{op1[7:0]}} : op1;
next_write_reg = 1'b1;
next_write_num = insn[15:12];
next_write_data = insn[22] ? {24'b0, swp_oldval[7:0]} : swp_oldval;
if(!rw_wait)
- next_swp_state = 2'b01;
+ next_swp_state = `SWP_READING;
$display("SWP: write stage");
end
default: begin end
busaddr = raddr;
/* rotate to correct position */
case(insn[6:5])
- 2'b00: begin end /* swp */
2'b01: begin /* unsigned half */
wr_data = {2{op2[15:0]}}; /* XXX need to store halfword */
data_size = 3'b010;
data_size = 3'b010;
lsrh_rddata = raddr[1] ? {{16{rd_data[31]}}, rd_data[31:16]} : {{16{rd_data[15]}}, rd_data[15:0]};
end
+ default: begin
+ wr_data = 32'hxxxxxxxx;
+ data_size = 3'bxxx;
+ lsrh_rddata = 32'hxxxxxxxx;
+ end
endcase
case(lsrh_state)
- 3'b001: begin
+ `LSRH_MEMIO: begin
rd_req = insn[20];
wr_req = ~insn[20];
next_write_num = insn[15:12];
if(insn[21] | !insn[24]) begin
outstall = 1'b1;
if(!rw_wait)
- next_lsrh_state = 3'b010;
+ next_lsrh_state = `LSRH_BASEWB;
end
$display("ALU_LDRSTRH: rd_req %d, wr_req %d", rd_req, wr_req);
end
- 3'b010: begin
+ `LSRH_BASEWB: begin
next_outbubble = 1'b0;
next_write_reg = 1'b1;
next_write_num = insn[19:16];
next_write_data = addr;
- next_lsrh_state = 3'b100;
+ next_lsrh_state = `LSRH_WBFLUSH;
end
- 3'b100: begin
+ `LSRH_WBFLUSH: begin
outstall = 0;
- next_lsrh_state = 3'b001;
+ next_lsrh_state = `LSRH_MEMIO;
end
default: begin end
endcase
- if ((lsrh_state == 3'b001) && flush) begin /* Reject it. */
+ if ((lsrh_state == `LSRH_MEMIO) && flush) begin /* Reject it. */
outstall = 1'b0;
- next_lsrh_state = 3'b001;
+ next_lsrh_state = `LSRH_MEMIO;
end
end
`DECODE_LDRSTR_UNDEFINED: begin end
align_s2 = raddr[0] ? {align_s1[7:0], align_s1[31:8]} : align_s1;
/* select byte or word */
align_rddata = insn[22] ? {24'b0, align_s2[7:0]} : align_s2;
- wr_data = insn[22] ? {4{op2[7:0]}} : op2; /* XXX need to actually store just a byte */
+ wr_data = insn[22] ? {24'h0, {op2[7:0]}} : op2;
data_size = insn[22] ? 3'b001 : 3'b100;
case(lsr_state)
- 3'b001: begin
- rd_req = insn[20] /* L */;
- wr_req = ~insn[20] /* L */;
+
+ `LSR_MEMIO: begin
+ rd_req = insn[20] /* L */ || insn[22] /* B */;
+ wr_req = !insn[20] /* L */ && !insn[22]/* B */;
next_write_reg = insn[20] /* L */;
next_write_num = insn[15:12];
if(insn[20] /* L */) begin
- next_write_data = align_rddata;
+ next_write_data = insn[22] /* B */ ? {24'h0, align_rddata[7:0]} : align_rddata;
end
- if(insn[21] /* W */ | !insn[24] /* P */) begin
+ if (insn[22] /* B */ && !insn[20] /* L */) begin
+ do_rd_data_latch = 1;
+ outstall = 1'b1;
+ if (!rw_wait)
+ next_lsr_state = `LSR_STRB_WR;
+ end else if(insn[21] /* W */ | !insn[24] /* P */) begin
outstall = 1'b1;
if(!rw_wait)
- next_lsr_state = 3'b010;
+ next_lsr_state = `LSR_BASEWB;
end
$display("LDRSTR: rd_req %d, wr_req %d, raddr %08x, wait %d", rd_req, wr_req, raddr, rw_wait);
end
- 3'b010: begin
+ `LSR_STRB_WR: begin
+ $display("LDRSTR: Handling STRB");
+ outstall = 1;
+ rd_req = 0;
+ wr_req = 1;
+ next_write_reg = 0;
+ case (busaddr[1:0])
+ 2'b00: wr_data = {rd_data_latch[31:8], op2[7:0]};
+ 2'b01: wr_data = {rd_data_latch[31:16], op2[7:0], rd_data_latch[7:0]};
+ 2'b10: wr_data = {rd_data_latch[31:24], op2[7:0], rd_data_latch[15:0]};
+ 2'b11: wr_data = {op2[7:0], rd_data_latch[23:0]};
+ endcase
+ if(insn[21] /* W */ | !insn[24] /* P */) begin
+ if(!rw_wait)
+ next_lsr_state = `LSR_BASEWB;
+ end else if (!rw_wait)
+ next_lsr_state = `LSR_WBFLUSH;
+ end
+ `LSR_BASEWB: begin
outstall = 1;
+ rd_req = 0;
+ wr_req= 0;
next_outbubble = 0;
next_write_reg = 1'b1;
next_write_num = insn[19:16];
next_write_data = addr;
- next_lsr_state = 3'b100;
+ next_lsr_state = `LSR_WBFLUSH;
end
- 3'b100: begin
+ `LSR_WBFLUSH: begin
+ rd_req = 0;
+ wr_req= 0;
outstall = 0;
- next_lsr_state = 3'b001;
+ next_lsr_state = `LSR_MEMIO;
end
default: begin end
endcase
- if ((lsr_state == 3'b001) && flush) begin /* Reject it. */
+ if ((lsr_state == `LSR_MEMIO) && flush) begin /* Reject it. */
outstall = 1'b0;
- next_lsr_state = 3'b001;
+ next_lsr_state = `LSR_MEMIO;
end
end
/* XXX ldm/stm incorrect in that stupid case where one of the listed regs is the base reg */
next_outbubble = rw_wait;
data_size = 3'b100;
case(lsm_state)
- 4'b0001: begin
+ `LSM_SETUP: begin
// next_regs = insn[23] ? op1[15:0] : op1[0:15];
/** verilator can suck my dick */
$display("LDMSTM: Round 1: base register: %08x, reg list %b", op0, op1[15:0]);
op1[8], op1[9], op1[10], op1[11], op1[12], op1[13], op1[14], op1[15]};
offset = 6'b0;
outstall = 1'b1;
- next_lsm_state = 4'b0010;
+ next_lsm_state = `LSM_MEMIO;
end
4'b0010: begin
rd_req = insn[20];
outstall = 1'b1;
if(next_regs == 16'b0) begin
- next_lsm_state = 4'b0100;
+ next_lsm_state = `LSM_BASEWB;
end
end
- 4'b0100: begin
+ `LSM_BASEWB: begin
outstall = 1;
next_outbubble = 0;
next_write_reg = insn[21] /* writeback */;
next_write_num = insn[19:16];
next_write_data = insn[23] ? op0 + {26'b0, prev_offset} : op0 - {26'b0, prev_offset};
- next_lsm_state = 4'b1000;
+ next_lsm_state = `LSM_WBFLUSH;
$display("LDMSTM: Stage 3: Writing back");
end
- 4'b1000: begin
+ `LSM_WBFLUSH: begin
outstall = 0;
- next_lsm_state = 4'b0001;
+ next_lsm_state = `LSM_SETUP;
end
default: $stop;
endcase
- if ((lsm_state == 4'b0001) && flush) begin /* Reject it. */
+ if ((lsm_state == `LSM_SETUP) && flush) begin /* Reject it. */
outstall = 1'b0;
- next_lsm_state = 4'b0001;
+ next_lsm_state = `LSM_SETUP;
end
$display("LDMSTM: Decoded, bubble %d, insn %08x, lsm state %b -> %b, stall %d", inbubble, insn, lsm_state, next_lsm_state, outstall);
end
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