chap4.c

摩托罗拉Mc6805利程

// Chapter 4 6805 C programs
// Jonathan W. Valvano
// This software accompanies the book,
// Embedded Microcomputer Systems: Real Time Interfacing
// published by Brooks Cole, 1999


// Program 4.3. This C function is nonreentrant because of the read-modify-write access to a global. 
unsigned int Money;  /* bank balance implemented as a global */
/* add 100 dollars */
void more(void){
	Money += 100;}

// Program 4.5. This C function is nonreentrant because of the write-read access to a global. 
int temp;  /* global temporary */
/* calculate x+2*d */
int mac(int x, int d){
	temp = x+2*d;    /* write to a global variable */
       return (temp);}  /* read from global */

// Program 4.7. This C function is nonreentrant because of the multi-step write access to a global. 
int info[2];  /* 32-bit global */
void set(int x, int y){
    info[0]=x;
    info[1]=y;}