void NewContext(int* SP) {
// SP for next task to go (arg #1) goes into HL
SP; FunctionArgToReg(H, L);
// Restores usermode status
SetStackPointerASM(_OldSP);
ExchangeRegs();
ReloadIndexes();
SaveContext();
// Switches to the process with stack in SP
ExchangeRegs();
GetStackPointerASM(_TempSP);
SetStackPointerREG(HL);
*CurrentSP=TempSP;
ExchangeRegs();
LoadContext();
if(ControlRequests==0) Halt("ISR IN USER MODE");
ControlRequests--;
IntsOn();
ImmediateReturn();
}
/// Switches CPU context to that of the specified thread
void SwitchContext(Thread* t) {
Thread* cur = GetCurrentThread();
// Save context for current thread
if (cur) {
SaveContext(cur->context);
if (cur->IsRunning()) {
ChangeReadyState(cur, true);
}
}
// Load context of new thread
if (t) {
SetCurrentThread(t);
ChangeReadyState(t, false);
t->status = (t->status | THREADSTATUS_RUNNING) & ~THREADSTATUS_READY;
t->wait_type = WAITTYPE_NONE;
LoadContext(t->context);
} else {
SetCurrentThread(nullptr);
}
}
/***
Stack:
VAR offset($fp) absolute
$sp ------------
local 3 16 56
local 2 12 52
local 1 8 48
ret addr 4 44
pre $fp 0 40
$fp ------------
args3 -4 36
args2 -8 32
args1 -12 28
old local 4 -16 24
old local 3 -20 20
old local 2 -24 16
old local 1 -28 12
old ret value -32 8
old ret addr -36 4
olc pre $fp -40 0
pre $fp -------------
*/
void MipsCode::BeginToMips(MiddleInstr* middle) {
SaveContext();
}