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/*--------------------------------------------------------------------

 * TITLE: Plasma Real Time Operating System Extensions

 * AUTHOR: Steve Rhoads (rhoadss@yahoo.com)

 * DATE CREATED: 12/17/05

 * FILENAME: rtos_ex.c

 * PROJECT: Plasma CPU core

 * COPYRIGHT: Software placed into the public domain by the author.

 *    Software 'as is' without warranty.  Author liable for nothing.

 * DESCRIPTION:

 *    Support simulation under Windows.

 *    Support simulating multiple CPUs using symmetric multiprocessing.

 *--------------------------------------------------------------------*/

#include "plasma.h"

#include "rtos.h"

/************** WIN32 Simulation Support *************/

#ifdef WIN32

#include <conio.h>

#define kbhit _kbhit

#define getch _getch

#define putch _putch

extern void __stdcall Sleep(unsigned long value);

#if OS_CPU_COUNT > 1

unsigned int __stdcall GetCurrentThreadId(void);

typedef void (*LPTHREAD_START_ROUTINE)(void *lpThreadParameter);

void * __stdcall CreateThread(void *lpsa, unsigned int dwStackSize,

   LPTHREAD_START_ROUTINE pfnThreadProc, void *pvParam,

   unsigned int dwCreationFlags, unsigned int *pdwThreadId);

static unsigned int ThreadId[OS_CPU_COUNT];

//PC simulation of multiple CPUs

void OS_InitSimulation(void)

{

   int i;

   ThreadId[0] = GetCurrentThreadId();

   for(i = 1; i < OS_CPU_COUNT; ++i)

      CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)OS_Start, NULL, 0, &ThreadId[i]);

}

#endif  //OS_CPU_COUNT > 1

static uint32 Memory[8];

//Simulates device register memory reads

uint32 MemoryRead(uint32 address)

{

   Memory[2] |= IRQ_UART_WRITE_AVAILABLE;    //IRQ_STATUS

   switch(address)

   {

   case UART_READ:

      if(kbhit())

         Memory[0] = getch();                //UART_READ

      Memory[2] &= ~IRQ_UART_READ_AVAILABLE; //clear bit

      return Memory[0];

   case IRQ_MASK:

      return Memory[1];                      //IRQ_MASK

   case IRQ_MASK + 4:

      Sleep(10);

      return 0;

   case IRQ_STATUS:

      if(kbhit())

         Memory[2] |= IRQ_UART_READ_AVAILABLE;

      return Memory[2];

   }

   return 0;

}

//Simulates device register memory writes

void MemoryWrite(uint32 address, uint32 value)

{

   switch(address)

   {

   case UART_WRITE:

      putch(value);

      break;

   case IRQ_MASK:

      Memory[1] = value;

      break;

   case IRQ_STATUS:

      Memory[2] = value;

      break;

   }

}

uint32 OS_AsmInterruptEnable(uint32 enableInterrupt)

{

   return enableInterrupt;

}

void OS_AsmInterruptInit(void)

{

}

#endif  //WIN32

#if OS_CPU_COUNT > 1

static volatile uint8 SpinLockArray[OS_CPU_COUNT];

/******************************************/

uint32 OS_CpuIndex(void)

{

#ifdef WIN32

   int i;

   unsigned int threadId=GetCurrentThreadId();

   for(i = 0; i < OS_CPU_COUNT; ++i)

   {

      if(threadId == ThreadId[i])

         return i;

   }

#endif

   //return MemoryRead(GPIO_CPU_INDEX);

   return 0; //0 to OS_CPU_COUNT-1

}

/******************************************/

//Symmetric Multiprocessing Spin Lock Mutex

uint32 OS_SpinLock(void)

{

   uint32 state, cpuIndex, i, ok, delay;

   volatile uint32 keepVar;

   cpuIndex = OS_CpuIndex();

   state = OS_AsmInterruptEnable(0);    //disable interrupts

   if(SpinLockArray[cpuIndex])

      return (uint32)-1;                //already locked

   delay = (4 + cpuIndex) << 2;

   //Spin until only this CPU has the spin lock

   for(;;)

   {

      ok = 1;

      SpinLockArray[cpuIndex] = 1;

      for(i = 0; i < OS_CPU_COUNT; ++i)

      {

         if(i != cpuIndex && SpinLockArray[i])

            ok = 0;   //Another CPU has the spin lock

      }

      if(ok)

         return state;

      SpinLockArray[cpuIndex] = 0;

      OS_AsmInterruptEnable(state);     //re-enable interrupts

      for(i = 0; i < delay; ++i)        //wait a bit

         ++ok;

      keepVar = ok;    //don't optimize away the delay loop

      if(delay < 128)

         delay <<= 1;

      state = OS_AsmInterruptEnable(0); //disable interrupts

   }

}

/******************************************/

void OS_SpinUnlock(uint32 state)

{

   uint32 cpuIndex;

   if(state == (uint32)-1)

      return;                           //nested lock call

   cpuIndex = OS_CpuIndex();

   SpinLockArray[cpuIndex] = 0;

}

#endif  //OS_CPU_COUNT > 1