X-Git-Url: http://git.joshuawise.com/firearm.git/blobdiff_plain/149bcd1aae858c157cb51b351187c66a99410d6d..58f12604629701572671898bbd9124b31c304a0c:/Issue.v?ds=inline diff --git a/Issue.v b/Issue.v index ef53bc3..a8274ec 100644 --- a/Issue.v +++ b/Issue.v @@ -4,24 +4,24 @@ module Issue( input clk, input Nrst, /* XXX not used yet */ - input stall, /* pipeline control */ + input stall_1a, /* pipeline control */ input flush, /* XXX not used yet */ - input inbubble, /* stage inputs */ - input [31:0] insn, - input [31:0] inpc, - input [31:0] cpsr, + input bubble_1a, /* stage inputs */ + input [31:0] insn_1a, + input [31:0] pc_1a, + input [31:0] cpsr_1a, - output reg outstall = 0, /* stage outputs */ - output reg outbubble = 1, - output reg [31:0] outpc = 0, - output reg [31:0] outinsn = 0 + output wire stall_0a, /* stage outputs */ + output reg bubble_2a = 1, + output reg [31:0] pc_2a = 0, + output reg [31:0] insn_2a = 0 /* XXX other? */ ); `ifdef COPY_PASTA_FODDER /* from page 2 of ARM7TDMIvE2.pdf */ - casex (insn) + casex (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) */ @@ -58,17 +58,17 @@ module Issue( idxbit = (16'b1) << r; endfunction - wire [3:0] rn = insn[19:16]; - wire [3:0] rd = insn[15:12]; - wire [3:0] rs = insn[11:8]; - wire [3:0] rm = insn[3:0]; - wire [3:0] cond = insn[31:28]; + wire [3:0] rn = insn_1a[19:16]; + wire [3:0] rd = insn_1a[15:12]; + wire [3:0] rs = insn_1a[11:8]; + wire [3:0] rm = insn_1a[3:0]; + wire [3:0] cond = insn_1a[31:28]; - wire [3:0] rd_mul = insn[19:16]; - wire [3:0] rn_mul = insn[15:12]; - wire [3:0] rs_mul = insn[11:8]; + wire [3:0] rd_mul = insn_1a[19:16]; + wire [3:0] rn_mul = insn_1a[15:12]; + wire [3:0] rs_mul = insn_1a[11:8]; - wire [3:0] alu_opc = insn[24:21]; + wire [3:0] alu_opc = insn_1a[24:21]; function alu_is_logical; input [3:0] op; @@ -100,18 +100,18 @@ module Issue( endfunction always @(*) - casez (insn) + casez (insn_1a) `DECODE_ALU_MULT: /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */ begin use_cpsr = `COND_MATTERS(cond); - use_regs = (insn[21] /* accum */ ? idxbit(rn_mul) : 0) | idxbit(rs_mul) | idxbit(rm); - def_cpsr = insn[20] /* setcc */; + use_regs = (insn_1a[21] /* accum */ ? idxbit(rn_mul) : 0) | idxbit(rs_mul) | idxbit(rm); + def_cpsr = insn_1a[20] /* setcc */; def_regs = idxbit(rd_mul); end // `DECODE_ALU_MUL_LONG: /* Multiply long */ `DECODE_ALU_MRS: /* MRS (Transfer PSR to register) */ begin - use_cpsr = `COND_MATTERS(cond) || (insn[22] == 0) /* Source = CPSR */; + use_cpsr = `COND_MATTERS(cond) || (insn_1a[22] == 0) /* Source = CPSR */; use_regs = 0; def_cpsr = 0; def_regs = idxbit(rd); @@ -126,7 +126,7 @@ module Issue( `DECODE_ALU_MSR_FLAGS: /* MSR (Transfer register or immediate to PSR, flag bits only) */ begin use_cpsr = `COND_MATTERS(cond); - use_regs = insn[25] ? 0 : idxbit(rm); + use_regs = insn_1a[25] ? 0 : idxbit(rm); def_cpsr = 1; def_regs = 0; end @@ -147,27 +147,27 @@ module Issue( `DECODE_ALU_HDATA_REG: /* Halfword transfer - register offset */ begin use_cpsr = `COND_MATTERS(cond); - use_regs = idxbit(rn) | idxbit(rm) | (insn[20] /* L */ ? 0 : idxbit(rd)); + use_regs = idxbit(rn) | idxbit(rm) | (insn_1a[20] /* L */ ? 0 : idxbit(rd)); def_cpsr = 0; - def_regs = insn[20] /* L */ ? idxbit(rd) : 0; + def_regs = insn_1a[20] /* L */ ? idxbit(rd) : 0; end `DECODE_ALU_HDATA_IMM: /* Halfword transfer - immediate offset */ begin use_cpsr = `COND_MATTERS(cond); - use_regs = idxbit(rn) | (insn[20] /* L */ ? 0 : idxbit(rd)); + use_regs = idxbit(rn) | (insn_1a[20] /* L */ ? 0 : idxbit(rd)); def_cpsr = 0; - def_regs = insn[20] /* L */ ? idxbit(rd) : 0; + def_regs = insn_1a[20] /* L */ ? idxbit(rd) : 0; end `DECODE_ALU: /* ALU */ begin - use_cpsr = `COND_MATTERS(cond) | (!insn[25] /* I */ && shift_requires_carry(insn[11:4])); + use_cpsr = `COND_MATTERS(cond) | (!insn_1a[25] /* I */ && shift_requires_carry(insn_1a[11:4])); use_regs = - (insn[25] /* I */ ? 0 : - (insn[4] /* shift by reg */ ? + (insn_1a[25] /* I */ ? 0 : + (insn_1a[4] /* shift by reg */ ? (idxbit(rs) | idxbit(rm)) : (idxbit(rm)))) | (((alu_opc != `ALU_MOV) && (alu_opc != `ALU_MVN)) ? idxbit(rn) : 0); - def_cpsr = insn[20] /* S */; + def_cpsr = insn_1a[20] /* S */; def_regs = alu_flags_only(alu_opc) ? 0 : idxbit(rd); end `DECODE_LDRSTR_UNDEFINED: /* Undefined. I hate ARM */ @@ -180,30 +180,30 @@ module Issue( `DECODE_LDRSTR: begin use_cpsr = `COND_MATTERS(cond); - use_regs = idxbit(rn) | (insn[20] /* L */ ? 0 : idxbit(rd)); + use_regs = idxbit(rn) | (insn_1a[25] /* I */ ? idxbit(rm) : 0) | (insn_1a[20] /* L */ ? 0 : idxbit(rd)); def_cpsr = 0; - def_regs = insn[20] /* L */ ? idxbit(rd) : 0; + def_regs = insn_1a[20] /* L */ ? idxbit(rd) : 0; end `DECODE_LDMSTM: /* Block data transfer */ begin use_cpsr = `COND_MATTERS(cond); - use_regs = idxbit(rn) | (insn[20] /* L */ ? 0 : insn[15:0]); - def_cpsr = insn[22]; /* This is a superset of all cases, anyway. */ - def_regs = (insn[21] /* W */ ? idxbit(rn) : 0) | (insn[20] /* L */ ? insn[15:0] : 0); + use_regs = idxbit(rn) | (insn_1a[20] /* L */ ? 0 : insn_1a[15:0]); + def_cpsr = insn_1a[22]; /* This is a superset of all cases, anyway. */ + def_regs = (insn_1a[21] /* W */ ? idxbit(rn) : 0) | (insn_1a[20] /* L */ ? insn_1a[15:0] : 0); end `DECODE_BRANCH: /* Branch */ begin use_cpsr = `COND_MATTERS(cond); use_regs = 0; def_cpsr = 0; - def_regs = 0; + def_regs = insn_1a[24] /* L */ ? (16'b1 << 14) : 0; end `DECODE_LDCSTC: /* Coprocessor data transfer */ begin use_cpsr = `COND_MATTERS(cond); use_regs = idxbit(rn); def_cpsr = 0; - def_regs = insn[21] /* W */ ? idxbit(rn) : 0; + def_regs = insn_1a[21] /* W */ ? idxbit(rn) : 0; end `DECODE_CDP: /* Coprocessor data op */ begin @@ -215,9 +215,9 @@ module Issue( `DECODE_MRCMCR: /* Coprocessor register transfer */ begin use_cpsr = `COND_MATTERS(cond); - use_regs = insn[20] /* L */ ? 0 : idxbit(rd); + use_regs = insn_1a[20] /* L */ ? 0 : idxbit(rd); def_cpsr = 0; - def_regs = insn[20] /* L */ ? idxbit(rd) : 0; + def_regs = insn_1a[20] /* L */ ? idxbit(rd) : 0; end `DECODE_SWI: /* SWI */ begin @@ -236,78 +236,74 @@ module Issue( endcase /* Condition checking logic */ - reg condition_met; + reg condition_met_1a; always @(*) - casez(insn[31:28]) - `COND_EQ: condition_met = cpsr[`CPSR_Z]; - `COND_NE: condition_met = !cpsr[`CPSR_Z]; - `COND_CS: condition_met = cpsr[`CPSR_C]; - `COND_CC: condition_met = !cpsr[`CPSR_C]; - `COND_MI: condition_met = cpsr[`CPSR_N]; - `COND_PL: condition_met = !cpsr[`CPSR_N]; - `COND_VS: condition_met = cpsr[`CPSR_V]; - `COND_VC: condition_met = !cpsr[`CPSR_V]; - `COND_HI: condition_met = cpsr[`CPSR_C] && !cpsr[`CPSR_Z]; - `COND_LS: condition_met = !cpsr[`CPSR_C] || cpsr[`CPSR_Z]; - `COND_GE: condition_met = cpsr[`CPSR_N] == cpsr[`CPSR_V]; - `COND_LT: condition_met = cpsr[`CPSR_N] != cpsr[`CPSR_V]; - `COND_GT: condition_met = !cpsr[`CPSR_Z] && (cpsr[`CPSR_N] == cpsr[`CPSR_V]); - `COND_LE: condition_met = cpsr[`CPSR_Z] || (cpsr[`CPSR_N] != cpsr[`CPSR_V]); - `COND_AL: condition_met = 1; - `COND_NV: condition_met = 0; - default: condition_met = 1'bx; + casez(insn_1a[31:28]) + `COND_EQ: condition_met_1a = cpsr_1a[`CPSR_Z]; + `COND_NE: condition_met_1a = !cpsr_1a[`CPSR_Z]; + `COND_CS: condition_met_1a = cpsr_1a[`CPSR_C]; + `COND_CC: condition_met_1a = !cpsr_1a[`CPSR_C]; + `COND_MI: condition_met_1a = cpsr_1a[`CPSR_N]; + `COND_PL: condition_met_1a = !cpsr_1a[`CPSR_N]; + `COND_VS: condition_met_1a = cpsr_1a[`CPSR_V]; + `COND_VC: condition_met_1a = !cpsr_1a[`CPSR_V]; + `COND_HI: condition_met_1a = cpsr_1a[`CPSR_C] && !cpsr_1a[`CPSR_Z]; + `COND_LS: condition_met_1a = !cpsr_1a[`CPSR_C] || cpsr_1a[`CPSR_Z]; + `COND_GE: condition_met_1a = cpsr_1a[`CPSR_N] == cpsr_1a[`CPSR_V]; + `COND_LT: condition_met_1a = cpsr_1a[`CPSR_N] != cpsr_1a[`CPSR_V]; + `COND_GT: condition_met_1a = !cpsr_1a[`CPSR_Z] && (cpsr_1a[`CPSR_N] == cpsr_1a[`CPSR_V]); + `COND_LE: condition_met_1a = cpsr_1a[`CPSR_Z] || (cpsr_1a[`CPSR_N] != cpsr_1a[`CPSR_V]); + `COND_AL: condition_met_1a = 1; + `COND_NV: condition_met_1a = 0; + default: condition_met_1a = 1'bx; endcase /* Issue logic */ -`define STAGE_EXECUTE 0 -`define STAGE_MEMORY 1 -/* Once it's hit writeback, it's essentially hit the regfile so you're done. */ - reg cpsr_inflight [1:0]; - reg [15:0] regs_inflight [1:0]; - - reg waiting_cpsr; - reg waiting_regs; - wire waiting = waiting_cpsr | waiting_regs; - - initial - begin - cpsr_inflight[0] = 0; - cpsr_inflight[1] = 0; - regs_inflight[0] = 0; - regs_inflight[1] = 0; - end - - always @(*) - begin - waiting_cpsr = use_cpsr & (cpsr_inflight[0] | cpsr_inflight[1]); - waiting_regs = |(use_regs & (regs_inflight[0] | regs_inflight[1])); - - outstall = (waiting && !inbubble) || stall; /* Happens in an always @*, because it is an exception. */ - end + /* Once it's hit writeback, it's hit the regfile via forwarding so you're done. */ + reg cpsr_inflight_2a = 0, cpsr_inflight_3a = 0; + reg [15:0] regs_inflight_2a = 0, regs_inflight_3a = 0; + wire waiting_cpsr_1a = use_cpsr & (cpsr_inflight_2a | cpsr_inflight_3a); + wire waiting_regs_1a = |(use_regs & (regs_inflight_2a | regs_inflight_3a)); + wire waiting_1a = waiting_cpsr_1a | waiting_regs_1a; + assign stall_0a = (waiting_1a && !bubble_1a && !flush) || stall_1a; + + reg delayedflush = 0; + always @(posedge clk/* or negedge Nrst*/) + if (!Nrst) + delayedflush <= 0; + else if (flush && stall_0a /* halp! I can't do it now, maybe later? */) + delayedflush <= 1; + else if (!stall_0a /* anything has been handled this time around */) + delayedflush <= 0; + /* Actually do the issue. */ - always @(posedge clk) + always @(posedge clk or negedge Nrst) begin - if (waiting) - $display("ISSUE: Stalling instruction %08x because %d/%d", insn, waiting_cpsr, waiting_regs); + if (waiting_1a) + $display("ISSUE: Stalling instruction %08x because %d/%d", insn_1a, waiting_cpsr_1a, waiting_regs_1a); - if(flush) - begin - cpsr_inflight[0] = 1'b0; - cpsr_inflight[1] = 1'b0; - regs_inflight[0] = 16'b0; - regs_inflight[1] = 16'b0; - end - else if (!stall) + if (!Nrst) begin + bubble_2a <= 1; + /*AUTORESET*/ + // Beginning of autoreset for uninitialized flops + cpsr_inflight_2a <= 1'h0; + cpsr_inflight_3a <= 1'h0; + insn_2a <= 32'h0; + pc_2a <= 32'h0; + regs_inflight_2a <= 16'h0; + regs_inflight_3a <= 16'h0; + // End of automatics + end else if (!stall_1a) begin - cpsr_inflight[0] <= cpsr_inflight[1]; /* I'm not sure how well selects work with arrays, and that seems like a dumb thing to get anusulated by. */ - cpsr_inflight[1] <= (waiting || inbubble || !condition_met) ? 0 : def_cpsr; - regs_inflight[0] <= regs_inflight[1]; - regs_inflight[1] <= (waiting || inbubble || !condition_met) ? 0 : def_regs; + cpsr_inflight_3a <= cpsr_inflight_2a; /* I'm not sure how well selects work with arrays, and that seems like a dumb thing to get anusulated by. */ + cpsr_inflight_2a <= (waiting_1a || bubble_1a || !condition_met_1a) ? 0 : def_cpsr; + regs_inflight_3a <= regs_inflight_2a; + regs_inflight_2a <= (waiting_1a || bubble_1a || !condition_met_1a) ? 0 : def_regs; - outbubble <= inbubble | waiting | !condition_met | flush; - outpc <= inpc; - outinsn <= insn; + bubble_2a <= bubble_1a | waiting_1a | !condition_met_1a | flush | delayedflush; + pc_2a <= pc_1a; + insn_2a <= insn_1a; end end endmodule