X-Git-Url: http://git.joshuawise.com/firearm.git/blobdiff_plain/6595c4c85a94d1cfaaec707cf341a4e356627d88..a4f724e659b1bf3afea9de4aaaf64517c3d9844d:/Issue.v diff --git a/Issue.v b/Issue.v index a745656..07c709d 100644 --- a/Issue.v +++ b/Issue.v @@ -2,47 +2,45 @@ module Issue( input clk, - input Nrst, + input Nrst, /* XXX not used yet */ input stall, /* pipeline control */ - input flush, + input flush, /* XXX not used yet */ input inbubble, /* stage inputs */ input [31:0] insn, input [31:0] inpc, input [31:0] cpsr, - output reg outstall, /* stage outputs */ - output reg outbubble, - output reg [31:0] outpc, - output reg [31:0] outinsn + output wire outstall, /* stage outputs */ + output reg outbubble = 1, + output reg [31:0] outpc = 0, + output reg [31:0] outinsn = 0 /* XXX other? */ ); - - `ifdef COPY_PASTA_FODDER /* from page 2 of ARM7TDMIvE2.pdf */ casex (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????00??????????????????????????: /* ALU */ - 32'b????00010?00????????00001001????: /* Atomic swap */ - 32'b????000100101111111111110001????: /* Branch */ - 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 */ - default: /* X everything else out */ + `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 */ + `DECODE_ALU_HDATA_REG: /* Halfword transfer - register offset */ + `DECODE_ALU_HDATA_IMM: /* Halfword transfer - immediate offset */ + `DECODE_ALU: /* ALU */ + `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_MRCMCR: /* Coprocessor register transfer */ + `DECODE_SWI: /* SWI */ + default: /* X everything else out */ endcase `endif @@ -103,118 +101,125 @@ module Issue( always @(*) casez (insn) - 32'b????000000??????????????1001????: /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */ + `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 */; def_regs = idxbit(rd_mul); end -// 32'b????00001???????????????1001????: /* Multiply long */ - 32'b????00010?001111????000000000000: /* MRS (Transfer PSR to register) */ +// `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_regs = 0; def_cpsr = 0; def_regs = idxbit(rd); end - 32'b????00010?101001111100000000????: /* MSR (Transfer register to PSR) */ + `DECODE_ALU_MSR: /* MSR (Transfer register to PSR) */ begin use_cpsr = `COND_MATTERS(cond); use_regs = idxbit(rm); def_cpsr = 1; def_regs = 0; end - 32'b????00?10?1010001111????????????: /* MSR (Transfer register or immediate to PSR, flag bits only) */ + `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); def_cpsr = 1; def_regs = 0; end - 32'b????00??????????????????????????: /* ALU */ - begin - use_cpsr = `COND_MATTERS(cond) | (!insn[25] /* I */ && shift_requires_carry(insn[11:4])); - use_regs = - (insn[25] /* I */ ? 0 : - (insn[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 */ | alu_is_logical(alu_opc); - def_regs = alu_flags_only(alu_opc) ? 0 : idxbit(rd); - end - 32'b????00010?00????????00001001????: /* Atomic swap */ + `DECODE_ALU_SWP: /* Atomic swap */ begin use_cpsr = `COND_MATTERS(cond); use_regs = idxbit(rn) | idxbit(rm); def_cpsr = 0; def_regs = idxbit(rd); end - 32'b????000100101111111111110001????: /* Branch */ + `DECODE_ALU_BX: /* Branch */ begin use_cpsr = `COND_MATTERS(cond); use_regs = idxbit(rm); def_cpsr = 0; // don't care, we'll never get there def_regs = 0; end - 32'b????000??0??????????00001??1????: /* Halfword transfer - register offset */ + `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)); def_cpsr = 0; def_regs = insn[20] /* L */ ? idxbit(rd) : 0; end - 32'b????000??1??????????00001??1????: /* Halfword transfer - immediate offset */ + `DECODE_ALU_HDATA_IMM: /* Halfword transfer - immediate offset */ begin use_cpsr = `COND_MATTERS(cond); use_regs = idxbit(rn) | (insn[20] /* L */ ? 0 : idxbit(rd)); def_cpsr = 0; def_regs = insn[20] /* L */ ? idxbit(rd) : 0; end - 32'b????011????????????????????1????: /* Undefined. I hate ARM */ + `DECODE_ALU: /* ALU */ + begin + use_cpsr = `COND_MATTERS(cond) | (!insn[25] /* I */ && shift_requires_carry(insn[11:4])); + use_regs = + (insn[25] /* I */ ? 0 : + (insn[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_regs = alu_flags_only(alu_opc) ? 0 : idxbit(rd); + end + `DECODE_LDRSTR_UNDEFINED: /* Undefined. I hate ARM */ begin use_cpsr = 0; use_regs = 0; def_cpsr = 0; def_regs = 0; end - 32'b????100?????????????????????????: /* Block data transfer */ + `DECODE_LDRSTR: + begin + use_cpsr = `COND_MATTERS(cond); + use_regs = idxbit(rn) | (insn[25] /* I */ ? idxbit(rm) : 0) | (insn[20] /* L */ ? 0 : idxbit(rd)); + def_cpsr = 0; + def_regs = insn[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); end - 32'b????101?????????????????????????: /* Branch */ + `DECODE_BRANCH: /* Branch */ begin use_cpsr = `COND_MATTERS(cond); use_regs = 0; def_cpsr = 0; - def_regs = 0; + def_regs = insn[24] /* L */ ? (16'b1 << 14) : 0; end - 32'b????110?????????????????????????: /* Coprocessor data transfer */ + `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; end - 32'b????1110???????????????????0????: /* Coprocessor data op */ + `DECODE_CDP: /* Coprocessor data op */ begin use_cpsr = `COND_MATTERS(cond); use_regs = 0; def_cpsr = 0; def_regs = 0; end - 32'b????1110???????????????????1????: /* Coprocessor register transfer */ + `DECODE_MRCMCR: /* Coprocessor register transfer */ begin use_cpsr = `COND_MATTERS(cond); use_regs = insn[20] /* L */ ? 0 : idxbit(rd); def_cpsr = 0; def_regs = insn[20] /* L */ ? idxbit(rd) : 0; end - 32'b????1111????????????????????????: /* SWI */ + `DECODE_SWI: /* SWI */ begin use_cpsr = `COND_MATTERS(cond); use_regs = 0; @@ -260,30 +265,50 @@ module Issue( reg cpsr_inflight [1:0]; reg [15:0] regs_inflight [1:0]; - reg waiting_cpsr; - reg waiting_regs; - wire waiting = waiting_cpsr | waiting_regs; - - always @(*) + initial begin - waiting_cpsr = use_cpsr & (cpsr_inflight[0] | cpsr_inflight[1]); - waiting_regs = |(use_regs & (regs_inflight[0] | regs_inflight[1])); + cpsr_inflight[0] = 0; + cpsr_inflight[1] = 0; + regs_inflight[0] = 0; + regs_inflight[1] = 0; end + wire waiting_cpsr = use_cpsr & (cpsr_inflight[0] | cpsr_inflight[1]); + wire waiting_regs = |(use_regs & (regs_inflight[0] | regs_inflight[1])); + wire waiting = waiting_cpsr | waiting_regs; + assign outstall = (waiting && !inbubble && !flush) || stall; + + reg delayedflush = 0; + always @(posedge clk/* or negedge Nrst*/) + if (!Nrst) + delayedflush <= 0; + else if (flush && outstall /* halp! I can't do it now, maybe later? */) + delayedflush <= 1; + else if (!outstall /* anything has been handled this time around */) + delayedflush <= 0; + /* Actually do the issue. */ - always @(*) - outstall = waiting; - - always @(posedge clk) + always @(posedge clk or negedge Nrst) 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) ? 0 : def_cpsr; - regs_inflight[0] <= regs_inflight[1]; - regs_inflight[1] <= (waiting | inbubble) ? 0 : def_regs; + if (waiting) + $display("ISSUE: Stalling instruction %08x because %d/%d", insn, waiting_cpsr, waiting_regs); - outbubble <= inbubble | waiting | !condition_met; - outpc <= inpc; - outinsn <= insn; + if (!Nrst) begin + cpsr_inflight[0] <= 0; + cpsr_inflight[1] <= 0; + regs_inflight[0] <= 0; + regs_inflight[1] <= 0; + outbubble <= 1; + end else if (!stall) + 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; + + outbubble <= inbubble | waiting | !condition_met | flush | delayedflush; + outpc <= inpc; + outinsn <= insn; + end end - endmodule