void LCDScreen::seeSamplingEdge(ticks_t time)
{
++edgeCounter;
// TODO According to the AT043TN24 datasheet data should be sampled on the
// falling edge. However the sc_lcd code drives on the falling edge so for
// the moment sample on the rising to match that.
if (DETracker.getSignal().getValue(time)) {
// Thb
const unsigned minHorizontalClks = 40;
// Th * tvb
const unsigned minVerticalClks = 5 * 520;
ticks_t lowEdges = edgeCounter - (lastDEHighEdge + 1);
if (lowEdges >= minVerticalClks) {
// VSync
x = y = 0;
screen.flip();
} else if (lowEdges >= minHorizontalClks) {
// HSync
x = 0;
++y;
}
if (x < screen.getWidth() && y < screen.getHeigth()) {
screen.writePixel(x++, y, DataTracker.getSignal().getValue(time));
}
lastDEHighEdge = edgeCounter;
}
}
SDRAM::Command SDRAM::getCommand(ticks_t time) const
{
uint32_t cmd = 0;
if (WE.getSignal().getValue(time))
cmd |= 0x1;
if (CAS.getSignal().getValue(time))
cmd |= 0x2;
if (RAS.getSignal().getValue(time))
cmd |= 0x4;
switch (cmd) {
default:
assert(0 && "Unexpected cmd");
case 0:
return Command::LOAD_MODE_REGISTER;
case 1:
return Command::AUTO_REFRESH;
case 2:
return Command::PRECHARGE;
case 3:
return Command::ACTIVE;
case 4:
return Command::WRITE;
case 5:
return Command::READ;
case 6:
return Command::BURST_TERMINATE;
case 7:
return Command::NOP;
}
}
bool SDRAM::getUDQMValue(ticks_t time) const
{
if (useUDQM)
return UDQM.getSignal().getValue(time);
// Otherwise use NOR of CAS and RAS signal to match the SDRAM slice.
return CAS.getSignal().getValue(time) == 0 &&
RAS.getSignal().getValue(time) == 0;
}
void SDRAM::seeCLKChange(const Signal &value, ticks_t time)
{
if (value.getValue(time)) {
// Rising edge.
Command newCommand = getCommand(time);
switch (newCommand) {
case Command::ACTIVE:
currentRow = A.getSignal().getValue(time) & ((1 << config.rowBits) - 1);
break;
case Command::AUTO_REFRESH:
case Command::NOP:
case Command::PRECHARGE:
break;
case Command::LOAD_MODE_REGISTER:
modeReg.set(A.getSignal().getValue(time));
break;
case Command::READ:
currentColumn =
A.getSignal().getValue(time) & ((1 << config.columnBits) - 1);
currentBank =
BA.getSignal().getValue(time) & ((1 << config.bankBits) - 1);
counter = 0;
break;
case Command::WRITE:
currentColumn =
A.getSignal().getValue(time) & ((1 << config.columnBits) - 1);
currentBank =
BA.getSignal().getValue(time) & ((1 << config.bankBits) - 1);
counter = 0;
break;
case Command::BURST_TERMINATE:
break;
}
if (newCommand != Command::NOP) {
currentCommand = newCommand;
}
switch (currentCommand) {
default:
break;
case Command::READ:
{
uint16_t mask = getReadWriteMask(time);
unsigned burstLength = modeReg.getReadBurstLength();
uint16_t data = mem[getMemoryIndex(burstLength)] & mask;
uint8_t readEdge = edgeNumber + modeReg.getCASLatency();
pendingReads.push(std::make_pair(data, readEdge));
++counter;
if (burstLength != 0 && counter == burstLength)
currentCommand = Command::NOP;
}
break;
case Command::WRITE:
{
unsigned burstLength = modeReg.getReadBurstLength();
if (WE.getSignal().getValue(time)) {
uint16_t mask = getReadWriteMask(time);
uint32_t index = getMemoryIndex(burstLength);
uint16_t old = mem[index];
uint16_t data = DQ.getSignal().getValue(time);
mem[index] ^= (old ^ data) & mask;
}
++counter;
if (burstLength != 0 && counter == burstLength)
currentCommand = Command::NOP;
}
break;
}
++edgeNumber;
} else {
// Falling edge.
if (!pendingReads.empty() && pendingReads.front().second == edgeNumber) {
DQPort->seePinsChange(Signal(pendingReads.front().first), time);
pendingReads.pop();
}
}
}