X-Git-Url: http://git.joshuawise.com/firearm.git/blobdiff_plain/9516520942af5c7dd24b0323b164c4ea2bd1dc01..2c523f8ab5b2d5e0d2a5e34f360d16439861171e:/Issue.v diff --git a/Issue.v b/Issue.v index a745656..fcc2c0c 100644 --- a/Issue.v +++ b/Issue.v @@ -2,20 +2,20 @@ 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 reg outstall = 0, /* stage outputs */ + output reg outbubble = 1, + output reg [31:0] outpc = 0, + output reg [31:0] outinsn = 0 /* XXX other? */ ); @@ -264,26 +264,37 @@ module Issue( 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; /* Happens in an always @*, because it is an exception. */ end /* Actually do the issue. */ - always @(*) - outstall = waiting; - always @(posedge clk) 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; + cpsr_inflight[1] <= (waiting || inbubble || !condition_met) ? 0 : def_cpsr; regs_inflight[0] <= regs_inflight[1]; - regs_inflight[1] <= (waiting | inbubble) ? 0 : def_regs; + regs_inflight[1] <= (waiting || inbubble || !condition_met) ? 0 : def_regs; + + if (waiting) + begin + $display("ISSUE: Stalling instruction %08x because %d/%d", insn, waiting_cpsr, waiting_regs); + end outbubble <= inbubble | waiting | !condition_met; outpc <= inpc; outinsn <= insn; end - endmodule