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moving in variable latency controls
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@Peter-Herrmann
Peter-Herrmann committed Apr 27, 2024
1 parent f4df8b1 commit ec84320
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Showing 2 changed files with 55 additions and 34 deletions.
4 changes: 1 addition & 3 deletions sim/Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -20,11 +20,9 @@ $(MEM_HEX):


$(TEST_EXE):
verilator -Wall -O0 --threads 4 --coverage --trace --cc $(RTL_TOP) --exe $(TEST_CPP) -I$(INC_DIRS) -o $@ --build
verilator -Wall -O3 --threads 4 --coverage --trace --cc $(RTL_TOP) --exe $(TEST_CPP) -I$(INC_DIRS) -o $@ --build

$(SIGNATURE): $(TEST_EXE) $(MEM_HEX)
ls -lah >> log.txt
tree -f >> log.txt
./obj_dir/$(TEST_EXE) >> log.txt
printf "\n\nTest complete, Signature File:\n\n" >> log.txt
cat $(SIGNATURE) >> log.txt
Expand Down
85 changes: 54 additions & 31 deletions sim/testbench.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -16,10 +16,16 @@ std::vector<uint64_t> readHexFile(const std::string& filename);
uint64_t readMemory(uint64_t addr, const std::vector<uint64_t>& memory, const std::vector<uint64_t>& bootloader,
std::unordered_map<uint64_t, uint64_t>& dynamic_memory,
uint64_t mem_max, uint64_t text_offset, uint64_t bl_size, uint64_t sig_addr, uint64_t sig_file_data);
bool setGnt(uint32_t *gnt_delay, bool *read_outstanding, bool req, bool we);
bool setRvalid(uint32_t *rvalid_delay, bool *read_outstanding);
uint32_t genGntDelay();
uint32_t genRvalidDelay();
bool setGnt(int *gnt_delay, bool *read_outstanding, bool req, bool we, bool rvalid);
bool setRvalid(int *rvalid_delay, bool *read_outstanding);
int genGntDelay();
int genRvalidDelay();


///////////////////////////////////////////////////////////////////////////////////////////////////
// Main //
///////////////////////////////////////////////////////////////////////////////////////////////////


int main(int argc, char** argv)
{
Expand Down Expand Up @@ -49,22 +55,27 @@ int main(int argc, char** argv)
const uint64_t sig_addr = 0x00000000FFFFFFF8;
const uint64_t end_addr = 0x00000000F0F0F0F0;
const uint32_t bl_size = bootloader.size();
const vluint64_t timeout_value = 2000000;
const vluint64_t timeout_value = 100000;

// Persistent data buffers for timing
uint32_t queued_instr = 0;
uint32_t latched_instr = 0;
bool latched_i_rvalid = 0;
bool queued_i_rvalid = 0;

uint64_t queued_data_read = 0;
uint64_t latched_data_read = 0;
bool queued_d_rvalid = 0;
bool latched_d_rvalid = 0;

// Variable Memory Latency Timing State
uint32_t i_gnt_delay = genGntDelay();
uint32_t i_rvalid_delay = genRvalidDelay();
bool i_read_outstanding = false;
int i_gnt_delay = genGntDelay();
int i_rvalid_delay = genRvalidDelay();
bool i_read_outstanding = false;

uint32_t d_gnt_delay = genGntDelay();
uint32_t d_rvalid_delay = genRvalidDelay();
bool d_read_outstanding = false;
int d_gnt_delay = genGntDelay();
int d_rvalid_delay = genRvalidDelay();
bool d_read_outstanding = false;


std::cout << "\n\n" <<
Expand Down Expand Up @@ -95,6 +106,7 @@ int main(int argc, char** argv)
bool posedge = (main_time % 4) == 1;
bool negedge = (main_time % 4) == 3;
bool mem_resp_cycle = (main_time % 4) == 2;
bool mem_gnt_cycle = (main_time % 4) == 0;

// Logging only for alert signal, arch tests do not quit on unaligned access
if (cpu->alert_o && cpu->clk_i)
Expand All @@ -120,25 +132,29 @@ int main(int argc, char** argv)
// MEMORY READ CONTROL //
/////////////////////////

// Delay data reads on sim cycle (1/4 clock period) or hold times violated, timing will be wrong
cpu->imem_rdata_i = latched_instr;
cpu->dmem_rdata_i = latched_data_read;
if (cpu->clk_i)
// Delay data reads one sim cycle (1/4 clock period) or hold times violated, timing will be wrong
if (mem_resp_cycle)
{
latched_instr = queued_instr;
latched_data_read = queued_data_read;
cpu->imem_rdata_i = queued_instr;
cpu->imem_rvalid_i = queued_i_rvalid;
cpu->dmem_rdata_i = queued_data_read;
cpu->dmem_rvalid_i = queued_d_rvalid;
}

if (mem_resp_cycle)
{
cpu->imem_gnt_i = setGnt(&i_gnt_delay, &i_read_outstanding, i_req, false);
cpu->imem_rvalid_i = setRvalid(&i_rvalid_delay, &i_read_outstanding);
cpu->dmem_gnt_i = setGnt(&d_gnt_delay, &d_read_outstanding, d_req, d_we);
cpu->dmem_rvalid_i = setRvalid(&d_rvalid_delay, &d_read_outstanding);
cpu->imem_gnt_i = setGnt(&i_gnt_delay, &i_read_outstanding, i_req, false, cpu->imem_rvalid_i);
cpu->dmem_gnt_i = setGnt(&d_gnt_delay, &d_read_outstanding, d_req, d_we, cpu->dmem_rvalid_i);
}

if (mem_gnt_cycle)
{
queued_i_rvalid = setRvalid(&i_rvalid_delay, &i_read_outstanding);
queued_d_rvalid = setRvalid(&d_rvalid_delay, &d_read_outstanding);
}

// Instruction Reads
if (cpu->imem_rvalid_i && negedge)
if (queued_i_rvalid && posedge)
{
uint64_t instruction_double = readMemory(i_addr_whole, memory, bootloader,
dynamic_memory, mem_max, text_offset,
Expand All @@ -150,7 +166,7 @@ int main(int argc, char** argv)


// Data Reads
if (cpu->dmem_rvalid_i && negedge)
if (queued_d_rvalid && posedge)
{
queued_data_read = readMemory(d_addr_whole, memory, bootloader, dynamic_memory,
mem_max, text_offset, bl_size, sig_addr, sig_file_data);
Expand Down Expand Up @@ -193,7 +209,7 @@ int main(int argc, char** argv)
if (posedge)
{
std::cout << " INSTRUCTION_ADDR: " + hexString((uint64_t)i_addr_whole, 8)
+ " INST: " + hexString((uint64_t)latched_instr, 8)
+ " INST: " + hexString((uint64_t)queued_instr, 8)
+ "\n";
}

Expand Down Expand Up @@ -225,6 +241,9 @@ int main(int argc, char** argv)
return 0;
}

///////////////////////////////////////////////////////////////////////////////////////////////////
// Utility Functions //
///////////////////////////////////////////////////////////////////////////////////////////////////


std::string hexString(uint64_t num, int width)
Expand Down Expand Up @@ -311,11 +330,13 @@ uint64_t readMemory(uint64_t addr, const std::vector<uint64_t>& memory, const st
}


bool setGnt(uint32_t *gnt_delay, bool *read_outstanding, bool req, bool we)
bool setGnt(int *gnt_delay, bool *read_outstanding, bool req, bool we, bool rvalid)
{
if (req || *read_outstanding)
if (!req || (*read_outstanding && !rvalid))
{
*gnt_delay = genGntDelay();
else if ( ( (*gnt_delay)-- ) == 0 )
}
else if ( ( (*gnt_delay)-- ) <= 0 )
{
*gnt_delay = genGntDelay();
*read_outstanding = (!we);
Expand All @@ -325,11 +346,13 @@ bool setGnt(uint32_t *gnt_delay, bool *read_outstanding, bool req, bool we)
}


bool setRvalid(uint32_t *rvalid_delay, bool *read_outstanding)
bool setRvalid(int *rvalid_delay, bool *read_outstanding)
{
if (!(*read_outstanding))
{
*rvalid_delay = genRvalidDelay();
else if ( ( (*rvalid_delay)-- ) == 0 )
}
else if ( ( (*rvalid_delay)-- ) <= 0 )
{
*rvalid_delay = genRvalidDelay();
*read_outstanding = false;
Expand All @@ -338,5 +361,5 @@ bool setRvalid(uint32_t *rvalid_delay, bool *read_outstanding)
return false;
}

uint32_t genGntDelay() { return 0; }
uint32_t genRvalidDelay() { return 0; }
int genGntDelay() { return 0; }
int genRvalidDelay() { return 0; }

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