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URL https://opencores.org/ocsvn/zipcpu/zipcpu/trunk

Subversion Repositories zipcpu

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    /zipcpu/trunk/rtl/core
    from Rev 18 to Rev 25
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Rev 18 → Rev 25

/cpuops.v
50,6 → 50,13
assign w_lsr_result = (|i_b[31:5])? 34'h00
: { 1'b0, i_a, 1'b0 } >> (i_b[4:0]);// LSR
 
 
wire signed [16:0] w_mpy_a_input, w_mpy_b_input;
wire signed [33:0] w_mpy_result;
assign w_mpy_a_input = { ((i_a[15])&&(i_op[2])), i_a[15:0] };
assign w_mpy_b_input = { ((i_b[15])&&(i_op[2])), i_b[15:0] };
assign w_mpy_result = w_mpy_a_input * w_mpy_b_input;
 
wire z, n, v;
reg c, pre_sign, set_ovfl;
always @(posedge i_clk)
67,7 → 74,8
casez(i_op)
4'b?000:{c,o_c } <= {(i_b>i_a),i_a - i_b};// CMP/SUB
4'b?001: o_c <= i_a & i_b; // BTST/And
// 4'h4: o_c <= i_a[15:0] * i_b[15:0];
4'h3: { c, o_c } <= {1'b0,w_mpy_result[31:0]}; // MPYU/S
4'h4: { c, o_c } <= {1'b0,w_mpy_result[31:0]}; // MPYU/S
4'h5: o_c <= w_rol_result; // ROL
4'h6: o_c <= { i_a[31:16], i_b[15:0] }; // LODILO
4'h7: o_c <= { i_b[15:0], i_a[15:0] }; // LODIHI
/zipcpu.v
106,8 → 106,9
//
///////////////////////////////////////////////////////////////////////////////
//
`define CPU_CC_REG 4'he
`define CPU_PC_REG 4'hf
`define CPU_CC_REG 4'he
`define CPU_TRAP_BIT 9
`define CPU_BREAK_BIT 7
`define CPU_STEP_BIT 6
`define CPU_GIE_BIT 5
132,7 → 133,7
// Debug interface -- outputs
output reg o_dbg_stall;
output reg [31:0] o_dbg_reg;
output reg [3:0] o_dbg_cc;
output reg [1:0] o_dbg_cc;
output wire o_break;
// Wishbone interface -- outputs
output wire o_wb_cyc, o_wb_stb, o_wb_we;
144,15 → 145,15
output wire o_op_stall;
output wire o_pf_stall;
output wire o_i_count;
 
 
// Registers
reg [31:0] regset [0:31];
 
// Condition codes
reg [3:0] flags, iflags; // (BREAKEN,STEP,GIE,SLEEP ), V, N, C, Z
wire [7:0] w_uflags, w_iflags;
reg break_en, step, gie, sleep;
reg [3:0] flags, iflags; // (TRAP,FPEN,BREAKEN,STEP,GIE,SLEEP ), V, N, C, Z
wire [9:0] w_uflags, w_iflags;
reg trap, break_en, step, gie, sleep;
 
// The master chip enable
wire master_ce;
163,9 → 164,9
// Variable declarations
//
reg [31:0] pf_pc;
reg new_pc;
reg new_pc, op_break;
wire clear_pipeline;
assign clear_pipeline = new_pc || i_clear_pf_cache;
assign clear_pipeline = new_pc || i_clear_pf_cache || op_break;
 
wire dcd_stalled;
wire pf_cyc, pf_stb, pf_we, pf_busy, pf_ack, pf_stall;
179,10 → 180,11
// Variable declarations
//
//
reg opvalid, op_wr_pc, op_break;
reg opvalid, opvalid_mem, opvalid_alu, op_wr_pc;
wire op_stall, dcd_ce;
reg [3:0] dcdOp;
reg [4:0] dcdA, dcdB;
reg dcdA_cc, dcdB_cc, dcdA_pc, dcdB_pc;
reg [3:0] dcdF;
reg dcdA_rd, dcdA_wr, dcdB_rd, dcdvalid,
dcdM, dcdF_wr, dcd_gie, dcd_break;
203,12 → 205,12
reg [4:0] alu_reg;
reg [3:0] opn;
reg [4:0] opR;
reg [1:0] opA_cc, opB_cc;
reg [31:0] r_opA, r_opB, op_pc;
wire [31:0] w_opA, w_opB;
wire [31:0] opA_nowait, opB_nowait, opA, opB;
reg opR_wr, opM, opF_wr, op_gie,
reg opR_wr, opR_cc, opF_wr, op_gie,
opA_rd, opB_rd;
wire [7:0] opFl;
wire [9:0] opFl;
reg [6:0] r_opF;
wire [8:0] opF;
wire op_ce;
247,7 → 249,7
// PIPELINE STAGE #5 :: Write-back
// Variable declarations
//
wire wr_reg_ce, wr_flags_ce, wr_write_pc;
wire wr_reg_ce, wr_flags_ce, wr_write_pc, wr_write_cc;
wire [4:0] wr_reg_id;
wire [31:0] wr_reg_vl;
wire w_switch_to_interrupt, w_release_from_interrupt;
272,32 → 274,34
assign dcd_stalled = (dcdvalid)&&(
(op_stall)
||((dcdA_stall)||(dcdB_stall)||(dcdF_stall))
||((opvalid)&&(op_wr_pc)));
||((opvalid)&&((op_wr_pc)||(opR_cc))));
//
// PIPELINE STAGE #3 :: Read Operands
// Calculate stall conditions
assign op_stall = (opvalid)&&(
((mem_stalled)&&(opM))
||((alu_stall)&&(~opM)));
assign op_stall = ((mem_stalled)&&(opvalid_mem))
||((alu_stall)&&(opvalid_alu));
assign op_ce = (dcdvalid)&&((~opvalid)||(~op_stall));
 
//
// PIPELINE STAGE #4 :: ALU / Memory
// Calculate stall conditions
assign alu_stall = (((~master_ce)||(mem_rdbusy))&&(opvalid)&&(~opM))
||((opvalid)&&(wr_reg_ce)&&(wr_reg_id == { op_gie, `CPU_PC_REG }));
assign alu_ce = (master_ce)&&(opvalid)&&(~opM)&&(~alu_stall)&&(~clear_pipeline);
assign alu_stall = (((~master_ce)||(mem_rdbusy))&&(opvalid_alu))
||((opvalid)&&(wr_reg_ce)&&(wr_reg_id[4] == op_gie)
&&(wr_write_pc)||(wr_write_cc));
assign alu_ce = (master_ce)&&(opvalid_alu)&&(~alu_stall)&&(~clear_pipeline);
//
assign mem_ce = (master_ce)&&(opvalid)&&(opM)&&(~mem_stalled)&&(~clear_pipeline)&&(set_cond);
assign mem_stalled = (mem_busy)||((opvalid)&&(opM)&&(
assign mem_ce = (master_ce)&&(opvalid_mem)&&(~mem_stalled)&&(~clear_pipeline)&&(set_cond);
assign mem_stalled = (mem_busy)||((opvalid_mem)&&(
(~master_ce)
// Stall waiting for flags to be valid
||((~opF[8])&&(
((wr_reg_ce)&&(wr_reg_id[4:0] == {op_gie,`CPU_CC_REG}))))
((wr_reg_ce)&&(wr_reg_id[4:0] == {op_gie,`CPU_CC_REG}))
// Do I need this last condition?
//||((wr_flags_ce)&&(alu_gie==op_gie))))
||(wr_flags_ce)))
// Or waiting for a write to the PC register
||((wr_reg_ce)&&(wr_reg_id[4] == op_gie)&&(wr_write_pc))));
// Or CC register, since that can change the
// PC as well
||((wr_reg_ce)&&(wr_reg_id[4] == op_gie)&&((wr_write_pc)||(wr_write_cc)))));
 
 
//
344,9 → 348,12
// Default values
dcdA[4:0] <= { instruction_gie, instruction[27:24] };
dcdB[4:0] <= { instruction_gie, instruction[19:16] };
dcdA_cc <= (instruction[27:24] == `CPU_CC_REG);
dcdB_cc <= (instruction[19:16] == `CPU_CC_REG);
dcdA_pc <= (instruction[27:24] == `CPU_PC_REG);
dcdB_pc <= (instruction[19:16] == `CPU_PC_REG);
dcdM <= 1'b0;
dcdF_wr <= 1'b1;
dcd_break <= 1'b0;
 
// Set the condition under which we do this operation
// The top four bits are a mask, the bottom four the
374,8 → 381,9
dcdF <= 4'h8; // This is unconditional
dcdOp <= 4'h2;
end
4'h4: begin // Load immediate special
dcdF_wr <= 1'b0; // Don't write flags
4'h4: begin // Multiply, LDI[HI|LO], or NOOP/BREAK
// Don't write flags except for multiplies
dcdF_wr <= (instruction[27:25] != 3'h7);
r_dcdI <= { 8'h00, instruction[15:0] };
if (instruction[27:24] == 4'he)
begin
384,7 → 392,6
dcdA_rd <= 1'b0;
dcdB_rd <= 1'b0;
dcdOp <= 4'h2;
dcd_break <= 1'b1;//Could be a break ins
end else if (instruction[27:24] == 4'hf)
begin // Load partial immediate(s)
dcdA_wr <= 1'b1;
391,9 → 398,15
dcdA_rd <= 1'b1;
dcdB_rd <= 1'b0;
dcdA[4:0] <= { instruction_gie, instruction[19:16] };
dcdA_cc <= (instruction[19:16] == `CPU_CC_REG);
dcdA_pc <= (instruction[19:16] == `CPU_PC_REG);
dcdOp <= { 3'h3, instruction[20] };
end else begin
; // Multiply instruction place holder
// Actual multiply instruction
r_dcdI <= { 8'h00, instruction[15:0] };
dcdA_rd <= 1'b1;
dcdB_rd <= (instruction[19:16] != 4'hf);
dcdOp[3:0] <= (instruction[20])? 4'h4:4'h3;
end end
4'b011?: begin // Load/Store
dcdF_wr <= 1'b0; // Don't write flags
407,8 → 420,6
dcdM <= 1'b1; // Memory operation
end
default: begin
dcdA <= { instruction_gie, instruction[27:24] };
dcdB <= { instruction_gie, instruction[19:16] };
dcdA_wr <= (instruction[31])||(instruction[31:28]==4'h5);
dcdA_rd <= 1'b1;
dcdB_rd <= instruction[20];
422,6 → 433,11
 
dcd_gie <= instruction_gie;
end
always @(posedge i_clk)
if (dcd_ce)
dcd_break <= (instruction[31:0] == 32'h4e000001);
else
dcd_break <= 1'b0;
 
 
//
429,18 → 445,21
// PIPELINE STAGE #3 :: Read Operands (Registers)
//
//
 
assign w_opA = regset[dcdA];
assign w_opB = regset[dcdB];
always @(posedge i_clk)
if (op_ce) // &&(dcdvalid))
begin
if ((wr_reg_ce)&&(wr_reg_id == dcdA))
r_opA <= wr_reg_vl;
else if (dcdA == { dcd_gie, `CPU_PC_REG })
else if ((dcdA_pc)&&(dcdA[4] == dcd_gie))
r_opA <= dcd_pc;
else if (dcdA[3:0] == `CPU_PC_REG)
r_opA <= (dcdA[4])?upc:ipc;
else if (dcdA_pc)
r_opA <= upc;
else if (dcdA_cc)
r_opA <= { w_opA[31:10], (dcd_gie)?w_uflags:w_iflags };
else
r_opA <= regset[dcdA];
r_opA <= w_opA;
end
wire [31:0] dcdI;
assign dcdI = { {(8){r_dcdI[23]}}, r_dcdI };
451,10 → 470,12
r_opB <= dcdI;
else if ((wr_reg_ce)&&(wr_reg_id == dcdB))
r_opB <= wr_reg_vl + dcdI;
else if (dcdB == { dcd_gie, `CPU_PC_REG })
else if ((dcdB_pc)&&(dcdB[4] == dcd_gie))
r_opB <= dcd_pc + dcdI;
else if (dcdB[3:0] == `CPU_PC_REG)
r_opB <= ((dcdB[4])?upc:ipc) + dcdI;
else if (dcdB_pc) // & dcdB[4] != dcd_gie thus is user
r_opB <= upc + dcdI;
else if (dcdB_cc)
r_opB <= { w_opB[31:10], (dcd_gie)?w_uflags:w_iflags} + dcdI;
else
r_opB <= regset[dcdB] + dcdI;
end
468,8 → 489,6
// these two bits are redundant. Hence the convoluted expression
// below, arriving at what we finally want in the (now wire net)
// opF.
`define NEWCODE
`ifdef NEWCODE
always @(posedge i_clk)
if (op_ce)
begin // Set the flag condition codes
485,27 → 504,15
endcase
end
assign opF = { r_opF[6], r_opF[3], r_opF[5], r_opF[1], r_opF[4:0] };
`else
always @(posedge i_clk)
if (op_ce)
begin // Set the flag condition codes
case(dcdF[2:0])
3'h0: opF <= 9'h100; // Always
3'h1: opF <= 9'h011; // Z
3'h2: opF <= 9'h010; // NE
3'h3: opF <= 9'h040; // GE (!N)
3'h4: opF <= 9'h050; // GT (!N&!Z)
3'h5: opF <= 9'h044; // LT
3'h6: opF <= 9'h022; // C
3'h7: opF <= 9'h088; // V
endcase
end
`endif
 
always @(posedge i_clk)
if (i_rst)
opvalid <= 1'b0;
else if (op_ce)
begin
opvalid <= 1'b0;
opvalid_alu <= 1'b0;
opvalid_mem <= 1'b0;
end else if (op_ce)
begin
// Do we have a valid instruction?
// The decoder may vote to stall one of its
// instructions based upon something we currently
515,8 → 522,14
// wait until our operands are valid, then we aren't
// valid yet until then.
opvalid<= (~clear_pipeline)&&(dcdvalid)&&(~dcd_stalled);
else if ((~op_stall)||(clear_pipeline))
opvalid <= 1'b0;
opvalid_alu <= (~dcdM)&&(~clear_pipeline)&&(dcdvalid)&&(~dcd_stalled);
opvalid_mem <= (dcdM)&&(~clear_pipeline)&&(dcdvalid)&&(~dcd_stalled);
end else if ((~op_stall)||(clear_pipeline))
begin
opvalid <= 1'b0;
opvalid_alu <= 1'b0;
opvalid_mem <= 1'b0;
end
 
// Here's part of our debug interface. When we recognize a break
// instruction, we set the op_break flag. That'll prevent this
526,25 → 539,26
// condition, replace the break instruction with what it is supposed
// to be, step through it, and then replace it back. In this fashion,
// a debugger can step through code.
// assign w_op_break = (dcd_break)&&(r_dcdI[15:0] == 16'h0001);
initial op_break = 1'b0;
always @(posedge i_clk)
if (i_rst)
op_break <= 1'b0;
else if (op_ce)
op_break <= (dcd_break)&&(r_dcdI[15:0] == 16'h0001);
else if ((~op_stall)||(clear_pipeline))
op_break <= 1'b0;
if (i_rst) op_break <= 1'b0;
else if (op_ce) op_break <= (dcd_break);
else if ((clear_pipeline)||(~opvalid))
op_break <= 1'b0;
 
always @(posedge i_clk)
if (op_ce)
begin
opn <= dcdOp; // Which ALU operation?
opM <= dcdM; // Is this a memory operation?
// opM <= dcdM; // Is this a memory operation?
// Will we write the flags/CC Register with our result?
opF_wr <= dcdF_wr;
opF_wr <= (dcdF_wr)&&((~dcdA_cc)||(~dcdA_wr));
// Will we be writing our results into a register?
opR_wr <= dcdA_wr;
// What register will these results be written into?
opR <= dcdA;
opR_cc <= (dcdA_wr)&&(dcdA_cc);
// User level (1), vs supervisor (0)/interrupts disabled
op_gie <= dcd_gie;
 
553,13 → 567,11
// assign so that there's no wait state between an
// ALU or memory result and the next register that may
// use that value.
opA_cc <= {dcdA[4], (dcdA[3:0] == `CPU_CC_REG) };
opA_rd <= dcdA_rd;
opB_cc <= {dcdB[4], (dcdB[3:0] == `CPU_CC_REG) };
opB_rd <= dcdB_rd;
op_pc <= dcd_pc;
//
op_wr_pc <= ((dcdA_wr)&&(dcdA[3:0] == `CPU_PC_REG));
op_wr_pc <= ((dcdA_wr)&&(dcdA_pc));
end
assign opFl = (op_gie)?(w_uflags):(w_iflags);
 
575,24 → 587,48
// We'll create a flag here to start our coordination. Once we
// define this flag to something other than just plain zero, then
// the stalls will already be in place.
assign dcdA_stall = (dcdvalid)&&(dcdA_rd)&&
(((opvalid)&&(opR_wr)&&(opR == dcdA))
||((mem_busy)&&(~mem_we)&&(mem_wreg == dcdA))
||((mem_valid)&&(mem_wreg == dcdA)));
assign dcdB_stall = (dcdvalid)&&(dcdB_rd)
&&(((opvalid)&&(opR_wr)&&(opR == dcdB))
||((mem_busy)&&(~mem_we)&&(mem_wreg == dcdB))
||((mem_valid)&&(mem_wreg == dcdB)));
assign dcdF_stall = (dcdvalid)&&(((dcdF[3])
||(dcdA[3:0]==`CPU_CC_REG)
||(dcdB[3:0]==`CPU_CC_REG))
&&((opvalid)&&(opR[3:0] == `CPU_CC_REG))
`define DONT_STALL_ON_OPA
`ifdef DONT_STALL_ON_OPA
reg opA_alu;
always @(posedge i_clk)
if (op_ce)
opA_alu <= (opvalid_alu)&&(opR == dcdA)&&(dcdA_rd);
assign opA = (opA_alu) ? alu_result : r_opA;
`else
assign opA = r_opA;
`endif
 
assign dcdA_stall = (dcdvalid)&&(dcdA_rd)&&(
`define DONT_STALL_ON_OPB
`ifdef DONT_STALL_ON_OPB
// Skip the requirement on writing back opA
// Stall on memory, since we'll always need to stall for a
// memory access anyway
((opvalid_mem)&&(opR_wr)&&(opR == dcdA))||
`else
((opvalid)&&(opR_wr)&&(opR == dcdA))||
`endif
((mem_busy)&&(~mem_we)&&(mem_wreg == dcdA)));
`ifdef DONT_STALL_ON_OPB
reg opB_alu;
always @(posedge i_clk)
if (op_ce)
opB_alu <= (opvalid_alu)&&(opR == dcdB)&&(dcdB_rd)&&(dcdI == 0);
assign opB = (opB_alu) ? alu_result : r_opB;
`else
assign opB = r_opB;
`endif
assign dcdB_stall = (dcdvalid)&&(dcdB_rd)&&(
((opvalid)&&(opR_wr)&&(opR == dcdB)
`ifdef DONT_STALL_ON_OPB
&&((opvalid_mem)||(dcdI != 0))
`endif
)||
((mem_busy)&&(~mem_we)&&(mem_wreg == dcdB)));
assign dcdF_stall = (dcdvalid)&&(
(((~dcdF[3]) ||(dcdA_cc) ||(dcdB_cc))
&&(opvalid)&&((opR_cc)||(opF_wr)))
||((dcdF[3])&&(dcdM)&&(opvalid)&&(opF_wr)));
assign opA = { r_opA[31:8], ((opA_cc[0]) ?
((opA_cc[1])?w_uflags:w_iflags) : r_opA[7:0]) };
assign opB = { r_opB[31:8], ((opB_cc[0]) ?
((opB_cc[1])?w_uflags:w_iflags) : r_opB[7:0]) };
 
//
//
// PIPELINE STAGE #4 :: Apply Instruction
599,7 → 635,7
//
//
cpuops doalu(i_clk, i_rst, alu_ce,
(opvalid)&&(~opM), opn, opA, opB,
(opvalid_alu), opn, opA, opB,
alu_result, alu_flags, alu_valid);
 
assign set_cond = ((opF[7:4]&opFl[3:0])==opF[3:0]);
630,8 → 666,7
initial alu_pc_valid = 1'b0;
always @(posedge i_clk)
alu_pc_valid <= (~i_rst)&&(master_ce)&&(opvalid)&&(~clear_pipeline)
&&((~opM)
||(~mem_stalled));
&&((opvalid_alu)||(~mem_stalled));
 
memops domem(i_clk, i_rst, mem_ce,
(opn[0]), opB, opA, opR,
672,6 → 707,8
assign wr_reg_ce = ((alu_wr)&&(alu_valid))||(mem_valid);
// Which register shall be written?
assign wr_reg_id = (alu_wr)?alu_reg:mem_wreg;
// Are we writing to the CC register?
assign wr_write_cc = (wr_reg_id[3:0] == `CPU_CC_REG);
// Are we writing to the PC?
assign wr_write_pc = (wr_reg_id[3:0] == `CPU_PC_REG);
// What value to write?
687,12 → 724,12
// When shall we write to our flags register? alF_wr already
// includes the set condition ...
assign wr_flags_ce = (alF_wr)&&(alu_valid);
assign w_uflags = { 1'b0, step, 1'b1, sleep, ((wr_flags_ce)&&(alu_gie))?alu_flags:flags };
assign w_iflags = { break_en, 1'b0, 1'b0, sleep, ((wr_flags_ce)&&(~alu_gie))?alu_flags:iflags };
assign w_uflags = { trap, 1'b0, 1'b0, step, 1'b1, sleep, ((wr_flags_ce)&&(alu_gie))?alu_flags:flags };
assign w_iflags = { trap, 1'b0, break_en, 1'b0, 1'b0, sleep, ((wr_flags_ce)&&(~alu_gie))?alu_flags:iflags };
// What value to write?
always @(posedge i_clk)
// If explicitly writing the register itself
if ((wr_reg_ce)&&(wr_reg_id[4:0] == { 1'b1, `CPU_CC_REG }))
if ((wr_reg_ce)&&(wr_reg_id[4])&&(wr_write_cc))
flags <= wr_reg_vl[3:0];
// Otherwise if we're setting the flags from an ALU operation
else if ((wr_flags_ce)&&(alu_gie))
702,7 → 739,7
flags <= i_dbg_data[3:0];
 
always @(posedge i_clk)
if ((wr_reg_ce)&&(wr_reg_id[4:0] == { 1'b0, `CPU_CC_REG }))
if ((wr_reg_ce)&&(~wr_reg_id[4])&&(wr_write_cc))
iflags <= wr_reg_vl[3:0];
else if ((wr_flags_ce)&&(~alu_gie))
iflags <= alu_flags;
729,20 → 766,30
always @(posedge i_clk)
if ((i_rst)||(i_halt))
break_en <= 1'b0;
else if ((wr_reg_ce)&&(wr_reg_id[4:0] == {1'b0, `CPU_CC_REG}))
else if ((wr_reg_ce)&&(~wr_reg_id[4])&&(wr_write_cc))
break_en <= wr_reg_vl[`CPU_BREAK_BIT];
assign o_break = (break_en)&&(op_break);
assign o_break = ((break_en)||(~op_gie))&&(op_break)&&(~alu_valid)&&(~mem_valid)&&(~mem_busy);
 
 
// The sleep register. Setting the sleep register causes the CPU to
// sleep until the next interrupt. Setting the sleep register within
// interrupt mode causes the processor to halt until a reset. This is
// a panic/fault halt.
// a panic/fault halt. The trick is that you cannot be allowed to
// set the sleep bit and switch to supervisor mode in the same
// instruction: users are not allowed to halt the CPU.
always @(posedge i_clk)
if ((i_rst)||((i_interrupt)&&(gie)))
sleep <= 1'b0;
else if ((wr_reg_ce)&&(wr_reg_id[3:0] == `CPU_CC_REG))
else if ((wr_reg_ce)&&(wr_write_cc)&&(~alu_gie))
// In supervisor mode, we have no protections. The
// supervisor can set the sleep bit however he wants.
sleep <= wr_reg_vl[`CPU_SLEEP_BIT];
else if ((wr_reg_ce)&&(wr_write_cc)&&(wr_reg_vl[`CPU_GIE_BIT]))
// In user mode, however, you can only set the sleep
// mode while remaining in user mode. You can't switch
// to sleep mode *and* supervisor mode at the same
// time, lest you halt the CPU.
sleep <= wr_reg_vl[`CPU_SLEEP_BIT];
else if ((i_halt)&&(i_dbg_we)
&&(i_dbg_reg == { 1'b1, `CPU_CC_REG }))
sleep <= i_dbg_data[`CPU_SLEEP_BIT];
750,7 → 797,7
always @(posedge i_clk)
if ((i_rst)||(w_switch_to_interrupt))
step <= 1'b0;
else if ((wr_reg_ce)&&(~alu_gie)&&(wr_reg_id[4:0] == {1'b1,`CPU_CC_REG}))
else if ((wr_reg_ce)&&(~alu_gie)&&(wr_reg_id[4])&&(wr_write_cc))
step <= wr_reg_vl[`CPU_STEP_BIT];
else if ((i_halt)&&(i_dbg_we)
&&(i_dbg_reg == { 1'b1, `CPU_CC_REG }))
766,10 → 813,10
||((master_ce)&&(alu_pc_valid)&&(step))
// If we encounter a break instruction, if the break
// enable isn't not set.
||((master_ce)&&(op_break))
||((master_ce)&&(op_break)&&(~break_en))
// If we write to the CC register
||((wr_reg_ce)&&(~wr_reg_vl[`CPU_GIE_BIT])
&&(wr_reg_id[4:0] == { 1'b1, `CPU_CC_REG }))
&&(wr_reg_id[4])&&(wr_write_cc))
// Or if, in debug mode, we write to the CC register
||((i_halt)&&(i_dbg_we)&&(~i_dbg_data[`CPU_GIE_BIT])
&&(i_dbg_reg == { 1'b1, `CPU_CC_REG}))
777,7 → 824,7
assign w_release_from_interrupt = (~gie)&&(~i_interrupt)
// Then if we write the CC register
&&(((wr_reg_ce)&&(wr_reg_vl[`CPU_GIE_BIT])
&&(wr_reg_id[4:0] == { 1'b0, `CPU_CC_REG }))
&&(~wr_reg_id[4])&&(wr_write_cc))
// Or if, in debug mode, we write the CC register
||((i_halt)&&(i_dbg_we)&&(i_dbg_data[`CPU_GIE_BIT])
&&(i_dbg_reg == { 1'b0, `CPU_CC_REG}))
790,6 → 837,19
else if (w_release_from_interrupt)
gie <= 1'b1;
 
initial trap = 1'b0;
always @(posedge i_clk)
if (i_rst)
trap <= 1'b0;
else if ((gie)&&(wr_reg_ce)&&(~wr_reg_vl[`CPU_GIE_BIT])
&&(wr_reg_id[4])&&(wr_write_cc))
trap <= 1'b1;
else if ((i_halt)&&(i_dbg_we)&&(i_dbg_reg[3:0] == `CPU_CC_REG)
&&(~i_dbg_data[`CPU_GIE_BIT]))
trap <= i_dbg_data[`CPU_TRAP_BIT];
else if (w_release_from_interrupt)
trap <= 1'b0;
 
//
// Write backs to the PC register, and general increments of it
// We support two: upc and ipc. If the instruction is normal,
859,16 → 919,16
if (i_dbg_reg[3:0] == `CPU_PC_REG)
o_dbg_reg <= (i_dbg_reg[4])?upc:ipc;
else if (i_dbg_reg[3:0] == `CPU_CC_REG)
o_dbg_reg <= { 25'h00, step, gie, sleep,
((i_dbg_reg[4])?flags:iflags) };
o_dbg_reg[9:0] <= (i_dbg_reg[4])?w_uflags:w_iflags;
end
always @(posedge i_clk)
o_dbg_cc <= { break_en, step, gie, sleep };
o_dbg_cc <= { gie, sleep };
 
always @(posedge i_clk)
o_dbg_stall <= (~i_halt)||(pf_cyc)||(mem_cyc)||(mem_busy)
o_dbg_stall <= (i_halt)&&(
(pf_cyc)||(mem_cyc)||(mem_busy)
||((~opvalid)&&(~i_rst))
||((~dcdvalid)&&(~i_rst));
||((~dcdvalid)&&(~i_rst)));
 
//
//

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