/* File **********THREAD1.C***********
   Statically allocated thread example
 Jonathan W. Valvano */
#include <HC11.h>
#include <vector.h>
struct	TCB
{   struct TCB *Next;      /* Link to Next TCB */
	unsigned char *SP;     /* Stack Pointer  */
	unsigned char Id;      /* 1,2 or 4 */
	unsigned char MoreStack[50];  /* additional stack */
	unsigned char CCR;     /* Initial CCR */
	unsigned char RegB;    /* Initial RegB */
	unsigned char RegA;    /* Initial RegA */
	unsigned int RegX;     /* Initial RegX */
	unsigned int RegY;     /* Initial RegY */
	void (*PC)(void);      /* Initial Program Counter */
};
int Sub(int j){ int i;
    PORTC=1;  /* Port C shows which program is being executed */
    i=j+1;
    return(i);}
void ProgA(){ int i;
    i=5;
    while(1) { PORTC=2; i=Sub(i);}}
void ProgB(){ int i;
    i=6;
    while(1) { PORTC=4; i=Sub(i);}}
typedef struct TCB TCBType;
typedef TCBType * TCBPtr;
TCBType sys[3]={
  {  &sys[1],           /* Pointer to Next */
	 &sys[0].MoreStack[49],    /* Initial SP */
	 1,                 /* Id */
	 { 0},
	 0x40,0,0,0,0,      /* CCR,B,A,X,Y */
	 ProgA, },          /* Initial PC */
  {  &sys[2],           /* Pointer to Next */
	 &sys[1].MoreStack[49],    /* Initial SP */
	 2,                 /* Id */
	 { 0},
	 0x40,0,0,0,0,      /* CCR,B,A,X,Y */
	 ProgA, },          /* Initial PC */
  {  &sys[0],           /* Pointer to Next */
	 &sys[2].MoreStack[49],    /* Initial SP */
	 4,                 /* Id */
	 { 0},
	 0x40,0,0,0,0,      /* CCR,B,A,X,Y */
	 ProgB, } };        /* Initial PC */
TCBPtr RunPt;   /* Pointer to thread currently running */
#pragma interrupt_handler ThreadSwitch()

void ThreadSwitch(){
asm(" ldx _RunPt\n"
	" sts 2,x");
      RunPt=RunPt->Next;
	  PORTB=RunPt->Id;  /* PortB shows which thread is running */
asm(" ldx _RunPt\n"
	" lds 2,x");
      TOC3=TCNT+20000;  /* Thread runs for 10 ms */
      TFLG1=0x20; }     /* acknowledge by clearing TOC3F */


main(){ DDRC=0xFF;      /* PortC are outputs */
       RunPt=&sys[0];   /* Specify first thread to run */
asm("  sei");
       TOC3vector=&ThreadSwitch;
       TFLG1 = 0x20;   /* Clear OC3F */
       TMSK1 = 0x20;   /* Arm TOC3 */
       TOC3=TCNT+20000;
	   PORTB=RunPt->Id;
asm("  ldx _RunPt\n"
	"  lds 2,x\n"
    "  cli\n"
	"  rti");}    /* Launch First Thread */