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Clean up the old/unused W_COUNTER parameter, and use a cleaner tie-off style for the counter CSRs

This commit is contained in:
Luke Wren 2022-10-10 16:33:31 +01:00
parent f771a1294d
commit ae4ddf7001
1 changed files with 14 additions and 22 deletions
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36
hdl/hazard3_csr.v
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@ -11,9 +11,6 @@
module hazard3_csr #( module hazard3_csr #(
parameter XLEN = 32, // Must be 32 parameter XLEN = 32, // Must be 32
parameter W_COUNTER = 64, // This *should* be 64, but can be reduced to save gates.
// The full 64 bits is writeable, so high-word increment can
// be implemented in software, and a narrower hw counter used
`include "hazard3_config.vh" `include "hazard3_config.vh"
, ,
`include "hazard3_width_const.vh" `include "hazard3_width_const.vh"
@ -426,26 +423,22 @@ always @ (posedge clk or negedge rst_n) begin
// Counters inhibited by default to save energy // Counters inhibited by default to save energy
mcountinhibit_cy <= 1'b1; mcountinhibit_cy <= 1'b1;
mcountinhibit_ir <= 1'b1; mcountinhibit_ir <= 1'b1;
end else if (CSR_COUNTER) begin end else begin
// Optionally hold the top (2 * XLEN - W_COUNTER) bits constant to
// save gates (noncompliant if enabled)
if (!(mcountinhibit_cy || debug_mode)) if (!(mcountinhibit_cy || debug_mode))
{mcycleh, mcycle} <= (({mcycleh, mcycle} + 1'b1) & ~({2*XLEN{1'b1}} << W_COUNTER)) {mcycleh, mcycle} <= ({mcycleh, mcycle} + 1'b1) & {2*XLEN{|CSR_COUNTER}};
| ({mcycleh, mcycle} & ({2*XLEN{1'b1}} << W_COUNTER));
if (!(mcountinhibit_ir || debug_mode) && instr_ret) if (!(mcountinhibit_ir || debug_mode) && instr_ret)
{minstreth, minstret} <= (({minstreth, minstret} + 1'b1) & ~({2*XLEN{1'b1}} << W_COUNTER)) {minstreth, minstret} <= ({minstreth, minstret} + 1'b1) & {2*XLEN{|CSR_COUNTER}};
| ({minstreth, minstret} & ({2*XLEN{1'b1}} << W_COUNTER));
if (wen_m_mode) begin if (wen_m_mode) begin
if (addr == MCYCLEH) if (addr == MCYCLEH)
mcycleh <= wdata_update; mcycleh <= wdata_update & {XLEN{|CSR_COUNTER}};
if (addr == MCYCLE) if (addr == MCYCLE)
mcycle <= wdata_update; mcycle <= wdata_update & {XLEN{|CSR_COUNTER}};
if (addr == MINSTRETH) if (addr == MINSTRETH)
minstreth <= wdata_update; minstreth <= wdata_update & {XLEN{|CSR_COUNTER}};
if (addr == MINSTRET) if (addr == MINSTRET)
minstret <= wdata_update; minstret <= wdata_update & {XLEN{|CSR_COUNTER}};
if (addr == MCOUNTINHIBIT) begin if (addr == MCOUNTINHIBIT) begin
{mcountinhibit_ir, mcountinhibit_cy} <= {wdata_update[2], wdata_update[0]}; {mcountinhibit_ir, mcountinhibit_cy} <= {wdata_update[2], wdata_update[0]} & {2{|CSR_COUNTER}};
end end
end end
end end
@ -464,11 +457,10 @@ always @ (posedge clk or negedge rst_n) begin
mcounteren_cy <= 1'b0; mcounteren_cy <= 1'b0;
mcounteren_tm <= 1'b0; mcounteren_tm <= 1'b0;
mcounteren_ir <= 1'b0; mcounteren_ir <= 1'b0;
end else if (CSR_COUNTER && U_MODE && wen_m_mode && addr == MCOUNTEREN) begin end else if (wen_m_mode && addr == MCOUNTEREN) begin
// Note this register only exists when U mode is implemented. mcounteren_cy <= wdata_update[0] && |CSR_COUNTER && |U_MODE;
mcounteren_cy <= wdata_update[0]; mcounteren_tm <= wdata_update[1] && |CSR_COUNTER && |U_MODE;
mcounteren_tm <= wdata_update[1]; mcounteren_ir <= wdata_update[2] && |CSR_COUNTER && |U_MODE;
mcounteren_ir <= wdata_update[2];
end end
end end
@ -506,10 +498,10 @@ always @ (posedge clk or negedge rst_n) begin
wdata_update[15], wdata_update[15],
wdata_update[12] && U_MODE, wdata_update[12] && U_MODE,
wdata_update[2] wdata_update[2]
}; } & {3{|DEBUG_SUPPORT}};
end end
if (enter_debug_mode) begin if (enter_debug_mode) begin
dcsr_cause <= dcause_next; dcsr_cause <= dcause_next & {3{|DEBUG_SUPPORT}};
end end
end end
end end