TempleOSTS_130315.ISO

TempleOS/Demo/Lectures/Spinning.CPP

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+//This task lets you hear how busy the CPU is.
+U0 LoadTask(I64)
+{
+  I64 i,j=100;
+//Preemption is ctrlled on a per task basis.
+//Preemption is OFF by default on new tasks.
+//It is turned on for user terminal tasks.
+  Preempt(ON);
+  while (TRUE) {
+    for (i=0;i<10000;i++)
+      InU8(0x21); //Roughly 1 microsecond on all PC's
+    Snd(j);
+    j+=20;
+    if (j>1000) j=100;
+  }
+}
+
+
+U0 SpinningPreempt()
+{
+  I64 i;
+  "Spinning with preemption....\n";
+  for (i=0;i<3000000;i++)
+    InU8(0x21); //This is a sample hardware stat read
+}
+
+U0 SpinningNoPreempt()
+{
+  I64 i;
+  Bool old_preempt;
+  "Spinning with no preemption...\n";
+
+//Put on screen before it starts.  Text lags by one refresh
+//and we might catch it in the middle of an update.
+  WinMgrSync;
+  WinMgrSync;
+  WinMgrSync;
+
+  old_preempt=Preempt(OFF);
+  for (i=0;i<3000000;i++)
+    InU8(0x21);
+  Preempt(old_preempt);
+}
+
+U0 SpinningNoInterrupts()
+{
+  I64 i;
+//Interrupts are ctrlled on a per task basis.
+  "Spinning with no interrupts...\n";
+  WinMgrSync;
+  WinMgrSync;
+  WinMgrSync;
+  Cli;
+  for (i=0;i<3000000;i++)
+    InU8(0x21);
+  Sti;
+}
+
+
+U0 CooperativeMultitaskingPreempt()
+{
+  F64 timeout=tT+3.0;
+
+  "Cooperative multitasking with preemption...\n";
+  while (tT<timeout) {
+    InU8(0x21);
+    Yield;
+  }
+}
+
+U0 CooperativeMultitaskingNoPreempt()
+{
+  F64 timeout=tT+3.0;
+  Bool old_preempt=Preempt(OFF);
+  "Cooperative multitasking with no preemption...\n";
+  while (tT<timeout) {
+    InU8(0x21);
+    Yield;
+  }
+  Preempt(old_preempt);
+}
+
+U0 CooperativeMultitaskingNoInterrupts()
+{
+  F64 timeout=tT+3.0;
+
+  Cli;
+  "Cooperative multitasking with no interrupts...\n";
+  while (tT<timeout) {
+    InU8(0x21);
+    Yield;
+  }
+  Sti;
+}
+
+U0 SpinningDemo()
+{
+  CTask *task=Spawn(&LoadTask);
+  SpinningPreempt;
+  SpinningNoPreempt;
+  SpinningNoInterrupts;
+  CooperativeMultitaskingPreempt;
+  CooperativeMultitaskingNoPreempt;
+  CooperativeMultitaskingNoInterrupts;
+  Kill(task);
+  Snd(0);
+}
+
+SpinningDemo;